SRI Paddy Cultivation requires less water and less expenditure gives more yields, Beneficial for small and marginal farmers.
SRI was first developed in Madagaskar during 1980's. Not known outside Madagaskar Until 1997. Its potential is under testing in China, Indonesia, Combodia, Thailand, Bangladesh, Sri Lanka, India. In A.P., SRI is experimented in all the 22 districts during 2003 Kharif with encouraging results. Over 1,00,000 farmers are experimenting with this system world wide at present.
SRI Technology Uses - Less External Inputs
In SRI Paddy Cultivation Less Seed (2kg/ac) is required and fewer plants per unit area (25x25cm) whre as in general Paddy Cultivation 20kg seed is required per acre.
SRI requires less expenditure on fertilizers and plant protection chemicals.
Root Growth
In SRI System Rice Crop grows healthy in natural conditions and its root growth can be massive receives nutrients from deeper layers of the soil. 3 hills under conventional method required 28kg of force to be pulled up where as single SRI rice plants required 53kg for uprooting.
SRI is initially labour intensive
Needs 50% more man days for transplanting and weeding.
Mobilises labour to work for profit.
It offers an alternative to resource poor, who puts in their family labour.
Once skills are learnt and implements are used, the labour costs will be lesser than the present day rice cultivation.
SRI encourages rice plant to grow healthy with
Large root volume
Profuse and strong tillers
Non lodging
Big panicle
More and well filled spikelets and higher grain weight
Resists insects because it allows rice to grow naturally
Tillering is greatly increased
30 tillers per plant are fairly easy to achieve
50 tillers pen plant are quite attainable.
With really good use of SRI, individual plants can have 100 fertile tillers or even more.
Because no set back due to early transplanting and no die back of roots.
Maximum tillering occurs concurrently with panicle initiation. More filled grain per panicle and no lodging of crop.
Everybody believe that Rice is an aquatic plant and grows best in standing water.
Rice is not an acquatic plant, it can survive in water but does not thrive under hypoxic conditions.
Rice plants spends lot of its energy to develop air pockets (aerenchyma tissue) in its roots under continous inundation.
70% of Rice root tips get degenerated by flowering period.
Under SRI Paddy fields are not flooded but keep the soil moist during vegetative phase later only one inch water depth is sufficient.
SRI requires only about half as much water as normally applied in irrigated rice.
Six Mechanisms and Processes for SRI
1. Early Transplanting Seedling 8-12 days old, when plant has only two small leaves, before fourth phyllochron.
More tillering potential
More root growth potential
2. Careful Transplanting Minimize trauma in transplanting. Remove plant from nursery with the seed, soil and roots carefully and place it in the field without plunging too deep into soil.
More tillering potential
3. Wide Spacing plant single seedlings, not in clumps, and in a square pattern, not rows, 25cm x 25cm or wider
More root growth potential
4. Weedling and Aeration needed because no standing water, use simple mechanical "rotating hoe" that churns up soil; 2 weedings required, with 4 recommended before panicle initiation; first weeding 10 days after transplanting.
More root growth, due to reduced weed competition, and aeration of soil, giving roots more oxygen and N due to increased microbial activity we left in soil; can add 1+tons per weeding? Each additional weeding after two rounds results in increased productivity up to 2 t/ha / weeding.
5. Water Management regular water applications to keep soil moist but not saturated, with intermittent dryings, alternating aerobic and anaerobic soil conditions.
More root growth because avoids root degeneration able to acquire more and more varied nutrients from the soil
6. Compost / FYM applied instead of or in addition to chemical fertilizer; 10 tons/ha;
More Plant growth because of better soil health and structure, and more balanced nutrient supply.
In SRI Cultivation 8 to 12 days old seedlings are planted. So root system grows well and gives 30 to 50 tillers. When all the 6 management practices are followed then per plant 50 to 100 tillers are produced and high yields can be realised.
Nursery Management
Seed rate 2 kg/ac
Nursery area 1 cent / ac
Select healthy seed
Pre-sprouted seeds are sown on raised nursery bed
Prepare nursery bed like garden crops
Apply a layer of fine manure
Spread sprouted seed sparcely
Cover with another layer of manure
Mulch with paddy straw
Water carefully
Banana leaf sheath may be used for easy lifting and transport of seedlings.
Main field preparation
Land preparation is not different from regular irrigated rice cultivation.
Levelling should be done carefully so that water can be applied very evenly.
At every 3m distance form a canal to facilitate drainage.
With the help of a marker draw lines both way at 25x25cm apart and transplant at the intersection.
Benefits of SRI
Higher yields - Both grain and straw
Reduced duration (by 10 days)
Lesser chemical inputs
Less water requirement
Less chaffy grain %
Grain weight increased without change in grain size
Higher head rice recovery
Withstood cyclonic gales
Cold tolerance
Soil health improves through biological activity
Soils
Definiton of Soil
Soil may be defined as a thin layer of earth crust which serves as a natural medium for the growth of the plants.
Soil Structure
It refers to the arrangement of soil particles. It is one of the important property of soil, since it influences aeration, permeability and water capacity.
Types of structure
Platy - Horizontal alignment
Prism like - Columnar type
Block like - Angular or sub- angular types
Spiroidal - Granular and crumb types
Soil Texture
The varying proportions of particles of different size groups in a soil constitute is known as soil texture.
The principle textural classes are clay, clay loam, sandy clay, silt clay, sandy clay loam, silty clay loam, sandy loam, silt loam, sand, loamy sand and silt.
It is the vertical section of the soil through all its horizons from the surface to the unaffected parent materials''. Generally the profile consists of three mineral horizons viz., A, B and C.
The surface soil or that layer of soil at the top which is liable to leaching and from which some soil constituents have been removed is known as horizon 'A' or the horizon of eluviation. The intermediate layer in which the materials leached from horizon 'A' have been re-deposited is known as horizon 'B' or the horizon of illuviation. The parent material from which the soil is formed is known as horizon ' C'.
The soil in each of these horizons is usually uniformly developed and presents a more or less homogeneous character. Each layer or horizon develops specific morphological features such as the size and shape of particles, their arrangement, colour, consistence etc. which distinguish from one horizon to another.
Study of soil profile is important since it reveals the characteristics and qualities of the soil.
Soil Composition
Soil consists of
organic matter
Soil organisms - Micro flora and Micro fauna.
Soil water
Soil air
Inorganic matter - Macro nutrients and Micro nutrients
Organic Matter
The plants and animals grown in weathered material and the organic residues left behind decay with time and become an integral part of the soil. The main source of soil organic matter is plant tissue. Animals are subsidiary source of soil organic matter.
The micro flora like bacteria, fungi, algae, actinomycetes, and micro fauna like protozoa, nematodes, macro fauna like earthworms, ants etc. play an important role in formation of organic matter.
The organic matter influences the soil in respect to colour, physical properties, supply of available nutrients and adsorptive capacity.
Soil Organisms
Soil is the habitat for enormous number of living organisms. Some of these organisms are visible to naked eye where as others can be seen by microscope only.
Roots of higher plants are considered as soil macro flora while bacteria, fungi, algae and actinomycetes are considered as soil micro flora. Protozoa and nematodes are the significant soil micro fauna where as the earthworms, moles and ants constitutes soil macro fauna.
Soil Water
In order to function as a medium for plant growth, soil must contain some water. The main functions of water in the soil are as follows:
Promotes many physical and biological activities of soil.
Acts as a solvent and carrier of nutrients.
As a nutrient itself.
Acts as an agent in photosynthesis process.
Maintains turgidity of plants.
Acts as an agent in weathering of rocks and minerals.
Soil Air
Oxygen is essential for all biological reactions occurring in soil. Its requirement is met from the soil air.
The gaseous phase of soil acts as a path way for intake of oxygen which is absorbed by soil micro organisms, plant roots and for escape of carbondioxide produced by the plants.
This two way process is called soil aeration. Soil aeration become critical for the plant growth when water content is high, because water replaces soil air.
Soil Inorganic Matter
The inorganic constituents of the soil comprises carbonates, soluble salts, free oxides of iron, aluminium and silica in addition to some amorphous silicates.
The inorganic constituents forms the bulk of the solid phase of the soil. Soils having more than 20% of the organic constituents are designated as organic soils.
Soils where inorganic constituents dominates they are called mineral soils. The majority of the soils in India are mineral soils.
Soil pH
The negative logarithm of hydrogen ion ( H +) concentration is called pH. Soil pH may be acidic, basic or neutral.
Soil Fertility
Soil fertility deals with the nutrient status or ability of soil to supply nutrients for plant growth under favourable environmental conditions such as light, temperature and physical conditions of soil.
Soil Productivity
Soil productivity is defined as the capability of the soil for producing a specified quantity of plant produce per unit area and the ability to produce sequence of crops under a specified system of management.
Problem Soils
The soils which owe characteristics that they can not be economically used for the cultivation of crops without adopting proper reclamation measures are known as problem soils.
Acid Soils
Those soils with pH less than 6.5 and which respond to liming may be considered as acid soils.
Reasons for Acidity
Humus decomposition results in release of large amounts of acids. There by lowering the pH.
Rainfall : In areas with more than 100 cm rainfall associated with high R.H., Ca, Mg is dissolved in water and leached out due to this base saturation of soil decreases.
Application of elemental sulphur under goes reactions resulting in formation of H2So4.
Continuous application of acid forming fertilizers like ammonium sulphates or ammonium chlorides results in depletion of Ca by CEC ( cation exchange capacity) phenomenon.
Parent Material : Generally rocks are considered as acidic, which contain large amount of silica (Si o2) when this combined with water, acidity increases.
Characteristics
PH is less than 6.5
This soils are open textured with high massive Structure.
Low in Ca, Mg with negligible amount of soluble salts.
This soils appear as brown or reddish brown, sandy loams or sands.
Injury to Crops
Direct Affects
Plant root system does not grow normally due to toxic hydrogen ions.
Permeability of plant membranes are adversely affected due to soil acidity.
Enzyme actions may be altered, since they are sensitive to PH changes.
Indirect Affects
Deficiency of Ca and Mg occur by leaching.
Al, Mn and Fe available in toxic amounts.
All the micro nutrients except molybdenum are available. So 'Mo' deficiency has been identified in leguminous crops.
Phosphorous gets immobilized and its availability is reduced.
Actvity of Micro Organisms
Most of the activities of beneficial organisms like Azatobacter and nodule forming bacteria of legumes are adversely effected as acidity increases.
Potassium sulphate is a suitable source of 'K' for acid soils. But MOP is better than K2So4 because Cl of MOP replaces -OH ions, their by release of -OH ions tends to increase the PH.
Alkaline Soils
Alkali soils are formed due to concentration of exchangeable sodium and high pH. Because of high alkalinity resulting from sodium carbonate the surface soil is discoloured to black; hence the term black alkali is used.
Reasons for Alkalinity
The excessive irrigation of uplands containing Na salts results in the accumulation of salts in the valleys.
In arid and semi arid areas salt formed during weathering are not fully leached.
In coastal areas if the soil contains carbonates the ingression of sea water leads to the formation of alkali soils due to formation of sodium carbonates.
Irrigated soils with poor drainage.
Characteristics
Injury to Crops
High exchangeable sodium decreases the availability of calcium, magnesium to plants.
Dispersion of soil particles due to high exchangeable 'Na' leads to poor physical condition of soil, low permeability to water and air, tends to be sticky when wet and becomes hard on drying.
Toxicity due to excess hydroxyl and carbonate ions.
Growth of plant gets affected mainly due to nutritional imbalance.
Restricted root system and delay in flowering in sensitive varieties.
Typical leaf burn in annuals and woody plants due to excess of chloride and sodium.
The process of amelioration consists of two steps.
To convert exchangeable sodium into water soluble form.
To leach out the soluble sodium from the field. Amendments used for reclamation of Alkali soils.
Gypsum
It is slightly soluble in water. So it should be applied well in advance.
Requrement
For every 1 m.e of exchangeable Na per 100 gm of soil, 1.7 tonns of Gypsum/ acre is to be added.
Application
If the requirement is 3 tonnes/ acre- apply in one dose.
If the requirement is 3 to 5 tonnes/acre- apply in 2 split doses.
If the requirement is 5 or more tonnes/ acre - apply in 3 split doses.
Use of Pyrites (Fe S2)
Sulphur present in pyrites causes decrease in pH of soil due to formation of H2So4.
H2So4 + Ca Co3 -- Ca S04 Ca So4 + Na --- Na So4 + Ca ( leachable)
Application of sulphur.
Application of molasses.
Drainage channels must be arranged around the field.
Growing the green manure crops and incorporate in the field.
Parameters
Details
pH
more than 8.3
EC
Less than 4 m.mhos/ cm
ESP
More than 15
Chemistry of soil solution
Dominated by carbonate and bicarbonate ions and high exchangeable sodium.
Effect of electrolyte on soil particles
Dispersion due to high amount of exchangeable sodium
Adverse effect on Plant
Alkalinity of soil solution
Geographic distribution
Semi arid and semi humid - areas.
Diagnosis under field condition
Presence of dispersed soil surface. Columnar structures present in the sub-soil
Saline Soils
The saline soils contains toxic concentration of soluble salts in the root zone. Soluble salts consists of chlorides and sulphates of sodium, calcium, magnesium. Because of the white encrustation formed due to salts, the saline soils are also called white alkali soils.
Reasons For Salinity
In arid and semi arid areas salts formed during weathering are not fully leached. During the periods of higher rainfall the soluble salts are leached from the more permeable high laying areas to low laying areas and where ever the drainage is restricted, salts accumulate on the soil surface, as water evaporates
The excessive irrigation of uplands containing salts results in the accumulation of salts in the valleys.
In areas having salt layer at lower depths in the profile, seasonal irrigation may favour the upward movement of salts.
Salinity is also caused if the soils are irrigated with saline water.
In coastal areas the ingress of sea water induces salinity in the soil.
Characteristics
Parameters
Details
PH
Less than 8.3
Ec
More than 4.0 m.mhos/ cm
ESP (exchangeable sodium %)
Less than 15
Chemistry of soil solution
Dominated by sulphate and chloride ions and low in exchangeable sodium
Effect of electrolytes on soil particles
Flocculation due to excess soluble salts.
Main effect on plant
High osmotic pressure of soil solution
Geographic distribution
Arid and semi arid regions.
Diagnosis under field condition
Presence of white crust
Presence of chloris barborata(weed)
Patchy growth of plants.
Injury to Crops
High osmotic pressure decreases the water availability to plants hence retardation of growth rate.
As a result of retarded growth rate, leaves and stems of affected plants are stunted.
Development of thicker layer of surface wax imparts bluish green tinge on leaves
The salts are to be leached below the root zone and not allowed to come up. However this practice is some what difficult in deep and fine textured soils containing more salts in the lower layers. Under this conditions a provision of some kind of sub-surface drains becomes important.
The required area is to be made into smaller plots and each plot should be bounded to hold irrigation water.
Separate irrigation and drainage channels are to be provided for each plot.
Plots are to be flooded with good quality water upto 15 - 20 cms and puddled. Thus, soluble salts will be dissolved in the water.
The excess water with dissolved salts is to be removed into the drainage channels.
Flooding and drainage are to be repeated 5 or 6 times till the soluble salts are leached from the soil to a safer limit.
Green manure crops like Daincha can be grown upto flowering stage and incorporated into the soil. Paddy straw can also be used.
Super phosphate, Ammonium sulphate or Urea can be applied in the last puddle. MOP and Ammonium chlorides should not be used.
Scrape the salt layer on the surface of the soil with spade.
Grow salt tolerant crops like sugar beet, tomato, beet root, barley etc
Before sowing , the seeds are to be treated by soaking the seeds in 0.1% salt solution for 2 to 3 hours.
Seed Material
Seed
Sexually or vegetatively propagated planting materials which are used for seeding and planting and as such should be free from any infection (pests and diseases) and should give a good crop stand by good seeding.
The ovule after fertilization develops into the seed with its coats completely fused together with the developing ovary wall or pericarp. The rice grain has the following structures.
The Pericarp or Fruit Coat
The pericarp is made up of distinct layers of quadrangular cells which forms the epicarp. These cells have slight thickening and are followed by cells which are much compressed and form the mesocarp consisting of two to three layers.
The endocarp is single layer of tube cells. The colour in the rice grain is found in the pericarp layer in the mature stage.
The Seed Coats
Due to the pressure brought out by the developing seed on the pericarp, the testa and tegmen become much pressed down and out of shape. A few layers of such cells below the pericarp can be diagnosed as the integuments of seed coats.
Aleurone Layer
A prominent layer of rectangular cells which contain protein lies next to the seed cents. This layer is known as the aleurone layer. This layer in rice is not coloured unlike in the case of maize.
It has been observed that in coloured varieties of rice, the aleurone layer is thicker than in the white rice varieties. The coarse rice generally have a larger aleurone layer than the finer rice. It has also been found that in poor soils, the aleurone layer is thin and improves in thickness with the fertility of the soil and manure.
The Endosperm
The entire mass of tissue below the aleurone layer is made up of cells which contain plenty of starch grains and these form the endosperm.
The Embryo
The scutellum has an upper free part which has a flesh projection known as ventral scale. Below this upper ventral scale and almost at the middle of the free part there is another out growth which can be called as the 'inner ventral scale' and this inner ventral scale is peculiar to rice embryos only.
On the surface of the embryo this out growth along with the epiblast forms a continuous covering around the plumule. The structure between the scutellum and the plumule is the mesocotyl.
Local varieties are nothing but traditional varieties but which are susceptible to diseases and pests and are having long duration for maturity. In case of rice - Krishnakatukalu, Basangulu.
High Yielding Varieties
High yielding varieties are dwarf varieties and having short duration with resistant to pests and diseases with maximum yield potential.
Eg: I.R -64, I.R - 36, I.R - 50.
Hybrids
A systematic and extensive evaluation of the experimental hybrids, across the country, at the twelve research net work centers has been taken up. About eight hundred experimental hybrids have been evaluated so far. During the wet season ( Kharif), the experimental hybrids are being evaluated at 12 centers, where as during dry season ( rabi ) the experimental hybrids are evaluated in seven centers, located in southern, western and eastern India. Very useful information on performance of hybrids and data on yield and yield components and other auxiliary characters of hybrids across the locations and seasons has been collected over the years.
As a result of concerted, goal oriented, time bound and co-ordinated efforts for the first time in the country, four rice hybrids were released for commercial cultivation during 1994, by the state variety release committee. These are APHR-1 and APHR- 2 for the Telangana and Rayalaseema regions of Andhra pradesh, MGR-1 for the Tamilnadu state and KRH-1 for Karnataka state. Subsequently two more hybrids, viz., CHRH -3 and DRRH-1 were released recently.
Genetically Engineered Seeds
One of the major concerns of cultivating hybrid varieties is that farmers can not use seed from the harvest for their next crop and thus have to buy new seed for each crop. More-over, the cost of hybrid seed is 5-20 times more than that of seeds of inbred varieties. Possibilities for true -to- type multiplication of hybrid rice are being explored through two approaches.
Production of artificial seeds through somatic embryogenesis and
Development of apomictic hybrid rice through wide hybridization and genetic engineering techniques.
Production of Artificial Seeds And Mass Propagation of True- Breeding Hybrids
Artificial seeds, consisting of somatic embryos, enclosed in a protective coating, are being proposed as low-cost, high-volume propagation system. The objective is to produce clonal seeds at a cost comparable with that of producing hybrid seed by conventional methods. Artificial seeds can be produced through somatic embryogenesis. This is the process by which somatic cells develop through the stages of embryogeny to give whole plants without gametic fusion. Somatic embryogenesis has been reported in more than 150 plant species. Somatic embryos have been induced from a variety of plant tissues, such as germinating seedlings shoot meristems, young inflorescence, nucellus, leaf, anther, root and others.
Artificial seed technology involves various steps for the production of somatic embryos and their utilization as commercial propagules.
Optimization of somatic embryogenesis system from cultured cells
Optimization of embryo maturation.
Automation of embryo production.
Production of mature synchronized embryos.
Encapsulation of embryos with necessary adjuvants.
Coating of encapsulated embryos.
Optimization of green house and field conditions for conversion of embryos into plants. And
Delivery system for artificial seeds.
Tissue Culture
"It is the process of growing tissue or cells which are exercised from healthy plants. These tissues are grown on nutrient medium under aseptic conditions."
It is also called as micro propagation. Tissue culture involves several techniques which are
Anther culture
Embryo rescue or ovary culture or Embryo culture.
Protoplast culture and protoplast fusion.
Somatic embryogenesis.
To develop a straight variety or true to type variety in crop plants, pure line selection method is adopted. In this method the seeds of pure lines are selected from homogeneous population of a particular crop and multiplied in the next season. This multiplication process is conducted in different co-ordinated centers and performance of the pure lines is tested. If the performance is good then the state varietal release committee or central varietal release committee releases the variety of that particular crop.
The seed supplied from Agricultural Research Stations, Department of Agriculture, or A.P. State seed corporation is not adequate to meet the requirements of the farmers. So the private seed producers are actively engaged in multiplication and supply of seed to the farmers. But the cost of seed is some times high and the quality also is not maintained. Hence, the farmers are motivated to develop their own seed in respect to varieties.
A seed village concept was introduced and the farmers were encouraged to develop their own seed. In this process the farmer is supplied with limited quantity of foundation seed or certified seed by Research stations or A.P State seed corporation. The farmer will grow variety with the seed supplied in a limited area with good management practices of both plant husbandry and plant protection.
He is also provided with information of the characters of the variety like duration, grain type, the time of panicle initiation etc. He observes the crop from time to time, and the off-types will be removed as and when noticed. He maintained a homogenous type of plants having the varietal characters . while harvesting he eliminates 1 meter crop from all sides of the field to avoid contamination from other varieties grown in neighbor hood and threshed, separately with all the care to prevent admixture of other varieties in threshing floor.
Like wise care will be taken during storage to maintain purity. Such seed will be used continuously year after year for the period of 3 to 4 years. Such seed can also be spread to the co-farmers interested in that specific Variety. After 4 years the farmer can again secure foundation seed or certified seed from the Research station. If it is practiced by atleast 25% of the farmers there will not be any scarcity for pure good seed.
Breeder seed is seed or vegetative propagating material produced by or under the direct control of the sponsoring plant breeder. It is the basis of the first and recurring increase of foundation seed.
Foundation Seed
It is obtained from breeder seed by direct increase and is the source of registered and or certified seed. Foundation seed is produced on experimental stations of Agricultural Universities and Government forms.
Certified Seeds
Certified seed is produced from foundation or registered seed. It is so known because it is certified by a seed certifying agency.
The certified seed is annually produced by progressive farmers according to standard seed production practices. Certified seed is available for general distribution to farmers for commercial crop production.
Public Hybrid
The hybrids developed by Govt. agencies or Govt. Institutions and Agricultural Universities are called public hybrids.
F1 Hybrid
The resultant seed obtained from crossing of two genetically dissimilar parents is called F1 Hybrids.
Seed viability is defined as " The capability of a seed to show living properties like germination and growth". Or
It is represented by germination percentage which expresses the number of seedlings that can be produced by a given number of seeds.
The duration of seed viability of rice varieties depends mainly on the following aspects.
Seed moisture % at the time of storage ( 10 to 12% is desirable).
Storage conditions.
Weather conditions ( relative humidity, rainfall)
Seed Moisture
The formation of germination inhibitors was accelerated under reduced oxygen tension and thereby the water content of the seed is increased which deteriorates viability.
Storage
The embryos and endosperm of seeds of different ages were found to respire, the rate being higher in fresh seeds then in older ones. Thus, the old seeds are living but failed to germinate.
The germination and viability of the rice seed are related to the formation of inhibitors during storage.
Weather Conditions
Higher relative humidity and rainfall during the storage periods will deteriorate the seed viability .
The paddy seed viability depends on the weather conditions. The seed viability deteriorate very fast during monsoon season.
Due to this, the seed harvested during rabi season do not retain its viability upto the next rabi season, because it passes through the monsoon weather conditions i.e., from June to October months, where as the kharif harvested seed retains its viability till the next kharif season.
Seed dormancy refers to the resting stage of embryo with low germinability of viable and freshly harvested grains. It is also defined as inability or failure of perfectly matured seed to germinate even when placed under conditions favourable for germination.
Seed dormancy is an important varietal trait in tropical rice where rain fall and high humidity are of frequent occurance during the maturity and harvest periods. Without dormancy, seed would germinate on the standing crop.
Classification of Dormancy
Seed Dormancy at Maturity Stage
Strong seed dormancy at maturity of the crop is a most desirable trait for all the kharif varieties. Some of the rice varieties ( Masuri, I.R -50) have little or no seed dormancy and in periods of wet weather at harvest time, the seed may germinate on the panicle itself.
Duration or Length of Dormancy
This refers to the period from harvest time to the time when the seeds have broken their dormancy.
Intensity of Dormancy
This refers to the level of breaking dormancy by artificial means, i.e., based on the germination percentage after heat treatment for four days at 50 degrees centigrade, and the rice varieties classified based on germination percentage as follows
Strongly Dormant
Varieties in which 50% of dormancy is broken after 4 days of heat treatment.
Moderately Dormant
Varieties in which 50 to 79% of dormancy is broken after 4 days of heat treatment.
Weakly Dormant
Varieties in which above 80% of dormancy is broken after 4 days of heat treatment.
Factors Influencing Dormancy Period
Climatic Conditions
Temperature
Rice produced during the cloudy wet season ( kharif) has a strong dormancy and longer duration of dormancy than that of produced during the summer dry season ( rabi).
This is mainly due to the temperature differences ( higher temperatures in rabi) during the ripening stage of the crop.
Relative Humidity
Higher R.H in atmosphere at maturity stage also increase the degree of dormancy.
Age of Seeds
A wide variation in maturity of seeds can be observed within a hill, i.e., between the mother tiller to tertiary tillers. Similarly there is about 7 to 10 days difference in the maturity of individual seeds within the same panicle.
The seeds in the upper portion of the panicle have earlier maturity than the lower portion of the panicle. So the duration, the dormancy of the individual seed varies with in the hill and also within the panicle.
Genetics of Dormancy
Genetically dormancy is dominant over non-dormancy. Dormancy is inherited independently and can combine with early maturity, photo sensitivity and also with a range of grain types.
Mechanism of Dormancy
Dormancy is the resultant of the slowing down effect of the metabolic process during seed maturation and also by the slow oxidation of the hormone IAA ( Indole Acetic Acid).
Hence, it is essential that any treatment aimed at breaking seed dormancy should hasten the rate of oxidation. Respiration is a strong competitor for the oxygen available for the dormancy breaking reaction.
Breaking Seed Dormancy
Among the several methods available the most suitable method to break seed dormancy at farmers level is nitric acid treatment. - Soaking the seed in o.1 N nitric acid i.e., 6.3 ml per lit. of water for 12 to 24 hours effectively breaks the seed dormancy, where as the varieties like MTU-1001 which is having 8 weeks and above dormancy duration should be treated with higher nitric acid concentration i.e., 10ml per lit. of water.
The seeds can be utilized for sowing immediately after the treatment or they can be dried thoroughly and can be utilized later for sowing.
Seed treatment refers to the application of fungicide, insecticide or a combination of both to seeds, such as to disinfect and disinfest them from seed-borne or soil-borne pathogenic organisms and crop pests both in field and in storage. It also refers to the subjecting of seeds to solar energy exposure, immersion in conditioned water etc.
Benefits of Seed Treatment
Prevention of spread of plant diseases.
Seed treatment protects seed from seed rot and seedling blight.
Improves germination.
Provides protection from insect pests.
Controlling soil insects.
Seed Treatment for Breaking Dormancy (Physiological Dormancy)
Dry Storage
For species where dormancy is naturally of short duration, it is often sufficient to store the samples in a dry place for a short period.
Pre-Chilling
The replicates for germination are placed in contact with the moist substratum and kept at low temperature for an initial period. Agricultural and vegetable seeds are kept at a temperature between 5 and 10 degrees Centigrade for an initial period of upto 7 days. In some cases it may be necessary to extend the pre-chilling period or to re-chilling.
Pre-Heating
The replicates for germination should be heated at a temperature not exceeding 40 degree C, with free air circulation, for a period of upto 7 days before they are placed under the prescribed germination conditions.
Light
The test should be illuminated during atleast 8 hours in every twenty four hours cycle and during the high temperature period when the seeds are germinated at alternating temperatures. The light intensity should be approximately 750 - 1250 lux from cool white lamps. Illumination is recommended especially for certain tropical and sub-tropical grasses.
Eg. Chloris gayana, Cynodon
Potassium Nitrate ( KNo3)
The germination substratum may be maintained with 0.2% solution of KNo3. It effectively break the seed dormancy.
Gibberellic Acid( GA3)
This GA3 method is recommended for wheat, oat etc.
Sealed Polythene Envelops
When a high proportion of fresh un-germinated seeds are found at the end of the standard test, then re-test in a sealed polythene envelop of sufficient size will usually induce these seeds to germinate.
In case of rice among the several methods for breaking dormancy are available the most suitable method at farmers level is nitric acid treatment.
Soaking the seed in 0.1 N nitric acid i.e., 6.3 ml per lit. of water for 12 to 24 hours effectively break the seed dormancy, where as the varieties like MTU-1001 which is having 8 weeks and above dormancy duration should be treated with higher nitric acid concentration i.e., 10ml per lit. of water.
The seed can be utilized for sowing immediately after the treatment or they can be dried thoroughly and can be utilized later for sowing.
Seed Treatment for Protection Against Pests and Diseases
Several insecticides and fungicides are used in seed treatment to protect the seeds from pests and diseases. These may be merchandized in combination or individual. In case of paddy the seed is treated with carbendism @ 1 gm / Kg of seed to protect against plant diseases.
The seedling dip in chlorpyriphos 2.5 EC solution @ 1ml /lit of water was suggested to protect against insect pests like rice stem borer, BPH etc.,
Seed germination is the resumption of growth by the embryo and development of young plant from the seed.
Germination, in a laboratory test, is the emergence and development from the seed embryo of those essential structures which, for the kind of being tested, indicate the ability to develop into a normal plant under favourable conditions in the soil.
Treatments for Promoting Germination
For reasons such as physiological dormancy, hard seededness, inhibitory substances a considerable number of hard or fresh seeds may remain at the end of the germination test.
When a proportion of fresh or dormant seeds remain at the end of the test period, complete germination can often be obtained by re-testing after a period of dry storage. The following methods may also be used to induce germination.
The purpose of seed storage is to maintain the seed in good physical and physiological condition from the time they are harvested until the time they are planted.
Stages of Seed Storage
The seeds are considered to be in storage from the moment they reach physiological maturity until they germinate or until they are thrown away because they are dead or otherwise worthless.
The entire storage period can be conveniently divided into following stages.
Storage on plants ( physiological maturity until harvest).
Harvest, until processed and stored in a warehouse.
In - storage ( warehouses)
In transit ( Railway wagons, trucks, carts, railway sheds etc.).
Nucleus Seed- From Breeder of Hybrid /Variety of Proprietor Breeder
Breeder Seed - From Breeder of Hybrid /Variety of Proprietor Breeder
Foundation Seed-From Breeder Seed
Certified/Truthful Seed- From Foundation Seed
Nucleus Seed /Breeder Seed à Foundation Seed Stage I/Stage-II –
Certified/Truthful Seed– Commercial grain for farmer’s consumption
Seed Production Planning
MOTTO: Plan every thing before starting Requirements for Quality seed production facilities
Good source of BS and F/S- Process start three years in advance before the actual seed production for marketing
Trusted Seed Growers
Qualified dedicated seed production team
Good Seed Processing plant Machinery capable to process the full planned marketing quantity.
Storage facilities including cold storage provision for off season storage, B/S and F/S
Seed Health Laboratory with/without finger printing facilities
Grow Out Farm (GOT)
Reliable, quick and economic transportation facilities
Knowledge of statuary Seed laws
Foundation Seed Production
MOTTO: Purity of Foundation will ensure minimum efforts in field for production of high quality seed
High purity of breeder seed.
For in-house hybrids Inspection of Breeder Seed plot by team of other breeders to produce best quality breeder seed.
For in-house foundation seed of proprietary hybrids involvement of concerned Breeder with F/S production official.
High Quality foundation seed minimizes the efforts for quality seed production.
Plan the production of foundation Seed three years in advance before the actual marketing of Seed.
Inspection of F/S plots by concern Breeders to ensure best quality
Seed Production
MOTTO: Dedicated Team work with Quality consciousness
Selection of reliable growers before start of season
Growers should be knowledgeable,financially sound and willing to take extra efforts to take up seed production operations
Seed production meeting before start of season for allocation of area to different production areas
Development of new production areas
Regular field inspections by seed production team at different stages of crop growth to advise growers on different operations
Random Field inspections by Seed Quality Field Team to monitor the various seed production operations
Midseason review of seed production to go for alternate area if falling short of targets.
Group and mass Seed Field inspections by seed production team at critical stages of crop growth in crucial highly cross pollinated crops like Pearl millet, maize sunflower and Jowar
Harvesting and threshing instructions to growers to avoid admixtures.
Other important operations / instructions as per crop growth
Seed Processing Plant Operations
MOTTO: Quality of processed seed should reflect on Market
Most important function after seed production
Overhauling and servicing of plant Machinery before start of season. Replace worn-out parts. Keep spares for emergencies. Extra Important implements to be kept in godown.
Trained operators of plant machinery
Separate godown for incoming, processed, sales return and ruminant seed.
Co-ordination with seed health team for sampling, dispatches and movement of Seed
Proper up storage and placement of screens,
Proper records of processed, remnant and processing losses to build full faith of seed grower in company
Record of seed arrival, dispatch and sales returns
Seed Health Laboratory
MOTTO: To ensure that only and only quality seed reaches the growers .
All facilities for testing of seed produced
To ensure that every lot of seed is tested for all the quality parameters of seed health before the dispatch of seed.
Trained qualified officicial for sampling of seed during processing of seed lots
Testing of all seed lots for germination, seed vigor, infestations and purity etc
Confidentiality of seed sampling and testing process
Seed health laboratory person to be trained in such a way that he catches the problems of seed even visually and to be very careful while testing these suspected lots for seed health.
Grow out tests (GOT)
MOTTO: To Test the Genetic purity of each and every seed lot
Allocation of area before the season to create all the facility required.
As no. of lots are known before the arrival of samples hence infra structure should be kept ready before testing season (maximum Kharif)
Highly technical qualified staff for the Grow out Tests.
Regular institutional Training of staff to update their knowledge
All seed lots of hybrids, parental lines and in-house varieties are to be tested through grow out tests.(GOT)
To strictly adhere to the plant characters of hybrids and varieties/lines
while taking the plant purity observations.
In high value crop seeds like sunflower and vegetable hybrids the Finger Printing technology to be used to check the Genetic purity of seed.
In case of crops where the time gap between seed arrival and dispatch is very less the finger printing has to be adopted to avoid any problem in field.
Do not look at short term gains while dispatching of seed at the times of Urgency of seed to market.
Handling of Seed complaints
Motto: Find the root cause of problem and rectify it immediately.
Mechanism to check the authenticity of seed complaints
Special cell to deal with seed complaints through marketing network.
To keep records of history of all seed lots to be kept to trace the reasons for complaints.
Find the reason for the complaints
If the faults found in production/processing/Grow out tests, mechanism to address those problems
Handling of Seed Seed law Enforcement Agencies
Motto: Hassle free marketing of seeds
To Deal with Seed law Enforcement agencies (Agric. Department and Court cases seed failures and consumers forum cases):
Separate person to deal with court cases
To keep the records ofall seed lots.
Knowledge of seed laws to ensure there no convictions.
Collection of judgments by various courts in country
Court cases can be handled easily with experience of system.
Not to accept faults in courts in seed failures but to fight it out
Seed Logistics
Motto: Placement of seed at market in time, safely with least costs in minimum time
Selection of good reliable transporters through tendering process required for bringing the raw seed from field and dispatch of packed seed in bulk.
For the small packings dispatches selection of transporters with maximum reach to destinations
Emphasis on cost reduction through proper planning of dispatches.
Safe movement of material by sending through quality vehicles with full protection
Use of railways instead of road transport for bulk transportation and small important seeds to far off locations
Monitoring of movement of seed till it reaches the destination
Land Preparation
Summer Ploughing
Summer ploughing improves soil structure due to alternate drying and cooling. Soil permeability is increased by breaking the compacted layers. Tillage improves soil aeration which helps in multiplication of micro organisms. Organic matter decomposition is hastened resulting in higher nutrient availability.
Increased aeration also helps in degradation of herbicide and pesticide residues and harmful allelopathic chemicals exuded by roots of previous crop or weed. It also helps in reducing the soil dwelling insect pests. In view of several benefits summer ploughing could be taken up at optimum moisture level.
Frequent harrowing has to be avoided as it results in destruction of soil structure. Tillage at improper moisture level is to be discouraged as it also damages soil structure and leads to development of hard pans.
Shallow Ploughing
It is generally followed by the most of the farmers repeatedly at the same depth (12-15 Cm). As a result of this hard pans are created, which inhibits the penetration of roots in deep rooted crops.
Eg: Cotton roots grow to a depth of 2 Mts. in deep alluvial soils without any pans, when hard pans are present they grow only upto hard pan (5 - 20 cm). But shallow ploughing is practiced to open the soil crust to increase the receptivity of rainfall.
Puddling
" Making soil impermeable by manipulating and compacting it in standing water, which reduces its apparent specific volume, thus facilitates transplanting." As a result of puddling, an impervious layer is formed below the surface which reduces deep percolation losses of water.
Levelling
Levelling is the tillage operation in which the soil is moved to a establish a desired soil elevation stage. Due to levelling the use of water and fertilizer efficiency increases effectively.
Harrowing
Harrowing is a secondary tillage operation which pulverizes, smoothens and packs the soil in seed-bed preparation and control weeds.
Conservation Tillage
The main objective is to conserve soil and moisture .Conservation tillage is an operation that is designed to maintain roughness of a field surface and leave most of the previous crop residues on the surface while providing a suitable seed-bed and weed control for the next crop.
This roughness reduces water run off and soil erosion.
Ridges and Furrows
A long, row ridge of earth with gently sloping sides and a shallow channel along the upper side, to control erosion by diverting surface run-off across the slope instead of permitting it to flow uninterrupted down to slope.
EG: Sugarcane, Sunflower, Vegetable crops.
Bunding
It is the process of forming an artificial earthern embankment made across slopping agricultural land to cut short lengthy soil slopes and reduces run-off and erosion.
These bunds are also formed along the contours across the slope of land in the low rainfall regions to conserve soil moisture.
Seeds are spread uniformly over well prepared land and is covered by ploughing or planking. It is most primitive method of sowing crops. The broadcasting has severaldisadvantages.
Seeds fall at different depths when broadcasted resulting in uneven stand.
It requires more seed rate.
Seeds fallen deep in the soil may not germinate.
Due to broadcasting excess competition at certain areas and no competition at all in other areas takes place in the field. So, yield returns will be decreased.
Water use efficiency and fertilizer efficiency will be decreased.
There is no possibility of controlling weeds by inter cultivation.
Drilling
To overcome the problems of broadcasting drilling the seeds in lines has come into practice. Weeds can be controlled economically by inter cultivation in line sown crops. In addition, drilling or line sowing facilitates uniform depth of sowing resulting in uniform crop stand. Seed rate can be considerably reduced drilling.
Planting
When individual seeds or seed material is placed in the soil by manual labour, it is called planting.
Generally crops with bigger sized seeds and those needing wider spacing are sown by this method. Eg : Cotton, Maize, Potato, Sugarcane, etc.
Transplanting
It is the process of planting seedlings in prepared main field. Small seeded crops like Tobacco, Chillies, Tomato, etc. are to be sown shallow and frequently irrigated for proper germination. Taking care of the germinating seed or seedlings which are spread over large area is a problem with regard to application of water, weed control, pest control etc. Therefore, seeds are sown in a small area called nursery and all the care is taken to raise the seedlings.
The advantages of transplanting saving in irrigation water, good stand establishment and increase in intensity of cropping. In respect to paddy the nursery is raised in small puddled plots and later transplanted in the main field at required spacing.
Seed Rate
The quality of seed required for sowing in a unit area of land. It is usually expressed in kg/ ha.
Spacing
The distance between crop row ( inter-row spacing) and between plants within the row (intra - row spacing) is referred as spacing. It is expressed in Cms.
Plant Population
Number of plants maintained in an unit area of land is known as plant population/ density. Establishment of optimum plant population is essential to get maximum yield. When sown densely competition among plants is more for growth factors resulting in reduction of yield.
Yield per plant decreases gradually as plant population per unit area is increased. The plant population density vary with the type of soil and crop. Optimum plant population density has to be maintained for securing maximum yield.
Nursery Raising
When more than one crop is to be grown in an year on the same piece of land, the time occupied by each crop has to be reduced.
The seedling growth in the early stages is very slow. Seedlings need extra care for establishing in the field because of their tenderness. Small seeded crops are to be sown shallow and frequently irrigated for proper germination.
Taking care of the germinating seed or seedlings which are spread over large area is a problem with regard to application of water, weed control, pest control etc. Therefore, seeds are sown in a small area called nursery and all the care is taken to raise the seedlings.
Transplanting
Method
Transplanting is usually done manually. In case of rice it is also done mechanically with transplantor provided the nursery is raised through dapog method.
Time
For achieving good results from transplanting, the seedlings are to be transplanted at optimum age and at proper depth. The age of seedlings for transplanting depends on crop and seasonal conditions.
Equipment
For Sowing
Country plough (Akkadi), Seed drill, Ferti-cum-seed drill, Mechanical seed drill are generally used.
It is an operation of soil cultivation performed in standing crop. It is also called as inter culturing. It facilitates good aeration, and better development of root system.
Weeding
Weeding is the process of eliminating competition of unwanted plants to the regular crop in respect to nutrition and moisture. So that crops can be grown profitably. It also facilitates other operations like irrigation and fertilizer application. The advantages of weeding are
Conservation of soil moisture.
Reduced competition for nutrients and water.
Purity of seed can be maintained.
Earthing Up
It is the process of putting the earth or soil just near the base for certain crops like Sugar cane, Cassava, Papaya, Potato, etc. to give support to the plants.
Sugarcane, Papaya, Banana - To avoid lodging
Cassava, Potato - To provide more soil volume for the growth of tubers. Vegetables - To facilitate irrigation.
Ridges and Furrows
It is also included in inter cultivation and generally done at the base of the crop to provide extra support against lodging and also provide soil volume for better growth. It also facilitates uniform spread of moisture during operation of irrigation.
Other Operations
Certain other operations like gap filling, thinning and propping are required as part of inter cultivation operations. In crops like Cotton, Paddy, the gap filling is done in missing areas of the planted main field to maintain optimum population .
Like wise thinning is also practiced in direct sown crops like Jowar, Chillies, to avoid over crowding and to maintain uniform plant stand. In crops like Sugarcane,betelwine, Grapes propping is necessary to support the main crop establishment.
It is an operation of cutting, picking, plucking, digging or combination of these for removing the useful part or economic end product, part from the plant.
Time
Crops can be harvested at physiological maturity or at harvest maturity. Crop is considered to be at physiological maturity when the translocation of photosynthates are stopped to economic part. If the crop is harvested early, the produce contain high moisture and more immature grains.
The yields will be low due to unfilled grains. Late harvesting results in shattering of grains, germination even before harvesting during rainy season and breakage during processing. Hence, harvesting at correct time is essential to get good quality of grains and higher yields.
Methods
Harvesting is done by either manually or by mechanical.
Manually
Manual harvesting is practiced by cutting crop with sickle or knife. In some crops like Sugarcane, Millets, Paddy the crop is cut with sickles and knives.
In some crops like Groundnut, tuber crops the plants are pulled and economic parts are separated. In other crops like Cotton, Chillies, and fruits the picking is practices to remove the economic parts like kappas, pods and fruits etc.
Mechanically
The combines are used to perform several operations such as cutting the crop, separating the grain from straw, cleaning the grain from chaff and transporting grains to the storage tank. Now a days the harvesting is exclusively for harvesting crops like Paddy and threshing paddy are used. Machines are now available for separating pods from the plants and also for shelling pods (decorticators) in respect to Groundnut crop.
Likewise machines are available for threshing sunflower heads, shelling of castor capsules and sowing of grain.
Drying and Processing
Drying is a process by which moisture content from grain is reduced to safe limit. Drying is done either by using solar energy or by artificial heating.
Processing is the conversion of the produce into a more finished condition before it is offered for sale.
Cleaning
The removal of foreign and dissimilar material by washing, screening, hand-picking, aspiration or any other mechanical means is known as cleaning. It is required to maintain the quality of the produce.
Equipment
Harvesting:Sickle, knife, combines, harvesters
Threshing : Bullocks, Tractors, Decorticators etc.
After harvest of the crop, the remnants of the plant viz. Straw, stubbles, leaves, etc. are ploughed into soil to decompose, there by providing source of organic matter for the next season crop.
In some places the flock of sheep are housed (penning) during night time. So that the excreta is collected on the field which is also a good source of organic nutrients.
The left over stubbles, plant residues in crops like Cotton, Chillies, Maize, Sunflower etc. may be burnt as part of soil sterilization as to reduce population of harmful microbes and soil dwelling insect pests.
In crops like Paddy the stubbles may be removed by ploughing after harvest to eliminate hibernating stem borer population. Field bunds may be trimmed to avoid hibernating grass hopper egg masses.
Why Fertilizers
Increasing agricultural production in India by area increasing process is no longer possible as cultivable land left over is only marginal. Further a considerable cultivable land is being diverted year after year for industrial purpose and housing etc. Hence self sufficiency in food lies in increasing the yield per unit area per unit time through adoption of modern agricultural technology.
It is universally accepted that the use of chemical fertilizers is an integral part of the package of practices for raising the agricultural production to a higher place. Studies conducted by the Food and Agricultural Organization of the United Nations (FAO) have established beyond doubt that there is a close relationship between the average crop yields and fertilizer consumption level. More-over the nutritional requirement of different crops could not be fully met with the use of organic manures like FYM and other bulky organic manures like Neem cake, Castor cake, Groundnut cake, etc., for want of their availability in adequate quantities.
Further fertilizers have the advantages of smaller bulk, easy transport, relatively quick in availability of plant-food constituents and the facility of their application in proportion suited to the actual requirements of crops and soils. Hence there is need for an efficient use of fertilizers as major plant nutrient resource in enhancing the farm productivity. Other resource of plant nutrients like organic manures, bio-fertilizers etc., also should be integrated to get the maximum agricultural output from every kilogram of applied nutrient in the form of fertilizers.
Plants require 16 essential elements for their normal growth and development.
The essential elements exist as structural components of a cell, maintain cellular organizations, function in energy transformations and in enzyme reaction.
Carbon, Hydrogen and Oxygen are three naturally occurring nutrients and form about 94 per cent of the dry weight of plants. These are the major components of carbohydrates, proteins and fats. Besides their structural role, they provide energy required for the growth and development of plants by oxidative breakdown of carbohydrates, proteins and fats during cellular respiration.
Nitrogen, Phosphorus and Potassium are three major or primary nutrients which are to be made available in larger quantities.
Nitrogen is an essential constituent of metabolically active compounds such as aminoacids, proteins, enzymes and some non-proteinous compounds. When nitrogen is a limiting factor, the rate and extent of protein synthesis are depressed and as a result plant growth is affected. The plant gets stunted and develops chlorosis.
Phosphorus is a structural component of all membranes, chloroplasts and mitochondria and a constituent of sugar phosphates, viz., ADP, ATP, nucleic acid, Phospholipids and phosphatides. Phosphorus plays an important role in energy transformations and metabolic processes in plants. It stimulates root growth.
Potassium plays an important role in the maintenance of cellular organisations by regulating permeability of cell membranes and keeping the protoplasm in a proper degree of hydration. It activates the enzymes in protein and carbohydrate metabolism and translocation of carbohydrates and imparts resistance to plants against fungal and bacterial disease.
Calcium, magnesium and sulphur are secondary nutrients which are required in relatively smaller but in appreciable quantities. Calcium, a constituent of the cell wall, an activator of different plant enzymes and is essential for the stability of cell membranes.
Magnesium is a constituent of chlorophyll and chromosome. It is known to play a catalytic role as an activator of a number of enzymes, most of w.hich are concerned with carbohydrate metabolism.
Sulphur is required to synthesize the sulphur containing amino acids and proteins, activity of proteolytic enzymes and increases oil content in oil bearing plants.
Iron, zinc, manganese, copper, boron, molybdenum and chlorine are required by plants in small quantities for their growth and development. Hence they are known as micronutrients or trace elements. The very fact that the micronutrient elements are required by plants in very low concentration suggests that they all function as catalysts or at least closely linked with some catalytic processes in plants. Manganese, zinc and copper are components of certain biological oxidation-reduction systems. Manganese performs some function in photosynthesis, acts as regulator to the intake and state of oxidation of certain elements. Zinc is concerned with the functioning of Sulphydryl compounds such as cystein, in the regulation of oxidation - reduction potential within the cells. Copper is a constituent of cytochrome oxidase and component of many enzymes like ascorbic acid oxidase, phenolase and lactase. Molybdenum is a constituent of nitrate reductase and nitrogenase enzyme and is associated with nitrogen utilization and in nitrogen fixation. Chlorine stimulates the activity of some enzymes and influences carbohydrate metabolism.
Boron helps in cell development by its influence on polysaccharide formation. It regulates translocation of sugars across membranes and polyphenolase activity. Iron is a constituent of cytochromes, haem and non haem enzymes. Perhaps the best known role of iron is its catalytic role in enzyme activity.
For obtaining maximum crop yields with maximum benefit to the cultivators, it is most essential that the crop plants should be fed properly with all nutrients. Soils deficient in particular nutrients must be supplied with fertilizers containing those plant nutrients.
Thus it is important to know which plant nutrients are lacking in a soil. Simple and elaborate tests have been developed by the agricultural scientist to estimate the nutritional requirements of soils and crops. These methods are known as diagnostic techniques. Fertilizer requirement is known by different diagnostic techniques and they are as follows ;
By Plant Observation
This is one of the method to know the fertilizer need of plants by means of the hunger signs of plants which can be detected by the eye.
The basis of the method is the fact that the plant suffering from severe deficiencies and excess of mineral nutrients usually developed well-defined and typical sign of disorders in various organs, particularly in the leaves. Usually, specific abnormal colours are developed in the leaves due to deficiency of plant nutrients.
Although the hunger signs in plants are easily observed, it is not easy to recognise the particular nutrient deficiency in nature due to various field conditions. This requires experience and practice in the field.
By Plant Analysis
The use of plant analysis as a tool to diagnose fertility status mainly consists of :
Plant tissue tests or rapid tests,
Total analysis,
Biochemical methods.
The basis of plant analysis for diagnostic purposes is that the amount of a given nutrient in a plant is an indication of the supply of that particular nutrient and is directly related to the quantity present in the soil. The normal growth of a plant is determined by the supply of the nutrients. However, there is one disadvantage with this method, that is, while the shortage of one nutrient can limit the growth, other nutrients may show higher contents in the cell sap irrespective of the supply.
The use of plant tissue tests as a means to diagnose soil fertility status has been found to be important. This is a rapid test of the cell sap of the growing plants. The sap from the ruptured cells is tested for unassimilated nitrogen, phosphorus, potash and other nutrients. Tissue tests are getting popular because of the convenience of handling and the small number of equipment needed for the test. The test can be made in a few minutes.
Total analysis is used extensively in research work as this gives a quantitative indication of the level of nutrients in plants. However, it should be remembered that the determination of total analysis gives both the assimilated and unassimilated nutrients. Many nutrients such as N, P, K, Ca, Mg, Mn, Zn, Cu, Fe, Mo and B can be determined by this method. Usually, the mature plants are selected for this testing.
Biochemical methods to determine the soil fertility require costly equipments, but offer good opportunities for research work. Two methods are recognised amongst biological tests. They are, use of higher plants, Microbiological methods.
By Fertilizer Experiments
In India, simple field experiments on farmers fields as well as complex field experiments are very popular.
Simple Field Experiments - In well managed state farms, the level of soil fertility is usually higher than in the farmers fields. This is due to the use of manures, fertilizers, good management practices, etc. Many experiments conducted on farmers fields have revealed the deficiency of nutrients at various levels. These experiment have to be simple in nature with N, P, K, NP, NK, PK, NPK as the treatments.
These simple field experiments on farmers fields are very educative and effective for the farmers, as they themselves see the deficiencies and the response of the nutrients. These trials are useful for advising the correct type and amount of fertilizer.
Complex Field Experiments
Complex field experiments allow the testing of many factors at a time and permit a study of interaction among various nutrients. Complex fertilizer trials helps in determining the correct kinds of fertilizer, amount and the method of application for each of the soil zone. These experiments are complicated, expensive and can be done only by experienced people.
By Soil Testing
Soil testing is one reliable diagnostic tool whose value in evaluating soil-fertility conditions has been recently recognised in India. Soil testing is multipurpose in nature. Its purposes are :
To group soils into classes relative to the levels of nutrients for suggesting fertilizer practices.
To predict the probability of getting a profitable response to the application of fertilizers.
To help evaluate soil profitability and To determine specific soil conditions i.e., alkalinity, salinity, acidity, that limit crop yields and can be improved with soil amendments and other management practices.
Organic fertilizers include both plant and animal bi-products. They are slow acting. Organic nitrogen fertilizers include oil cakes, fish manure, dried blood from slaughter houses etc., where as organic phosphorus from bone meal and organic potassium from cattle dung ash, wood ash, leaf mould, tobacco stems and water hyacinth.
Organic Manures
Manures are organic or inorganic substances applied to the soil to supply one or more nutrients to plants to obtain increased yields.
Manures are classified as follows
Manures
Organic manures
Inorganic manures
Bulky
Concentrated
Artificial
Bulky (Slow acting with large quantities of organic matter) Eg: Cattle, Sheep Poultry, Pig, Goat,, Horse manures, Compost, Green Manures, Sewage.Sludge.
Concentrated(Quick acting with small quantity of organic matter.Eg: Groundnut cake, Castor cake, Bonemeal, Blood meal, Horn meal, Wood ash, Cotton and Linseed Meal.
(Artificial manures,Chemical fertilizers very quick acting with No organic matter.Eg: Nitrogenous, Ammonium,Phosphatic, Potassic and Sulphate fertilizers.
Nitrogen is the first fertilizer element of the macronutrients usually applied in commercial fertilizers. Nitrogen is very important nutrient for plants and it seems to have the quickest and most pronounced effect.
Role of Nitrogen In Plants
Nitrogen is of special importance in the formation of protein in plants,
It forms a constituent of every living cells in the plants,
It is also present in chlorophyll,
It is involved in photosynthesis, respiration and protein synthesis,
It plays an important role in vegetative growth and it imparts dark green colour to plants.
If excess nitrogen is applied it delays ripening by encouraging more vegetative growth. The leaves acquire a dark green colour, become thick and leathery and in some cases crinkled. The plants become more liable to attack of pests and diseases. In case of cereal crops, the straw becomes weak, and the crop very often lodges and straw and grain ratio is increased. Excess nitrogen deteriorates the quality of some crops such as potato, barley and sugarcane. It delays reproductive growth and may adversely affect fruit and grain quality.
The deficiency of Nitrogen leads to formation of yellowish or light green coloured leaves and plant become stunted. The leaves and young fruits tend to drop prematurely. The kernels of cereals and the seed of other crops do not attain their normal size, and become shrivelled and light in weight.
Phosphorus
Phosphorus is the second fertilizer element and it is an essential constituent of every living cells and for the nutrition of plant and animal. It takes active part in all types of metabolism of plant. It is an essential constituent of majority of enzymes and also structural component of membrane system of cell, chloroplasts and the mitochondria. It is intimately associated with the life process.
Phosphorus stimulates root development and growth in the seedling stage and there by it helps to establish the seedlings quickly. It hastens leaf development and encourages greater growth of shoots and roots. It enhances the development of reproductive parts and thus bringing about early maturity of crops particularly the cereals. It increases the number of tillers in cereal crops and also strengthen the straw and thus helps to prevent the lodging. It stimulates the flowering, fruit setting and seed formation and the development of roots, particularly of root crops. Phosphorus has a special action on leguminous crops. It induces nodule formation and rhizobial activity.
Excess phosphorus leads to profuse root growth, particularly of the lateral and fibrous rootlets. It leads to some trace element deficiencies particularly iron and zinc.
Deficiency of phosphorus leads to restricted root and shoot growth, leaves may shed prematurely, flowering and fruiting may be delayed considerably. In case of potato tubers phosphorus deficiency leads to formation of rusty brown lessions.
Potassium
Potassium is the third fertilizer element. Potassium acts as a chemical traffic policeman, root booster, stalk strengthener, food former, sugar and starch transporter, protein builder, breathing regulator, water stretcher and as a disease retarder but it is not effective without its co-nutrients such as nitrogen and phosphorus.
Potassium is an essential element for the development of chlorophyll. It plays an important role in photosynthesis, i.e., converting carbon-dioxide and hydrogen into sugars, for translocation of sugars, and in starch formation. It improves the health and vigour of the plant, enabling it to withstand adverse climatic condition. It increases the crop resistance to certain diseases. Potash plays a key role in production of quality vegetables. Potassium is an enzyme activator and increases the plumpness and boldness of grains and seeds. It improves the water balance. Promotes metabolism and increases the production of carbohydrates.
Potassium deficiency causes stunting in growth with shortening of internodes and bushy in appearance, brings about chlorosis, i.e., yellowing of leaves and leaf scorch in case of fruit trees. It is also responsible for the 'dying back tips' of shoots. Its deficiency leads to reduction in photosynthesis, blackening of tubers in case of potato, tips or margin of lower leaves of legumes, maize, cotton, tobacco and small grains are either scorched or burnt.
Secondary Nutrients
Secondary nutrients include calcium, magnesium and sulphur, which play an important role in plant growth and development. The details of these nutrients are given below.
Calcium
Calcium as calcium pectate is an important constituent of cell wall and required for cell division. It is a structural component of chromosomes. It includes stiffness to straw and there by tends to prevent lodging. It enhances the nodule formation in legumes, helps in translocation of sugars, neutralizes organic acids which may become poisonous to plants. It is an essential co-factor or an activator of number of enzymes. It improves the intake of other plant nutrients, specially nitrogen and trace elements by correcting soil pH. Excessive amounts of calcium can decrease the availability of many micronutrients.
Deficiency of calcium lead to 'Die back' at the tips and margins of young leaves. Normal growth of plants is arrested i.e., roots may become short, stubby and bushy, leaves become wrinkled and the young leaves of cereal crops remain folded. The acidity of cell sap increases abnormally and it hampers the physiological function of plant. As a result of which plant suffers and causes the death of plant at last.
Magnesium
Magnesium is an essential constituent of chlorophyll. Several photosynthetic enzymes present in chlorophyll requires magnesium as an activator. It is usually needed by plants for formation of oils and fats. It regulates the uptake of nitrogen and phosphorus from the soil. Magnesium may increase crop resistance to drought and disease.
Deficiency of magnesium leads to yellowing of the older leaves known as chlorosis. Acute deficiency of magnesium also causes premature defoliation. In case of maize the leaves develop interveinal white strips, in cotton they change to purplish red, veins remain dark green, in soybean they turn yellowish and in apple trees, brown patches (blotches) appear on the leaves.
Sulphur
Sulphur has specified role in initiating synthesis of proteins. Sulphur is an important nutrient for oil seeds, crucifers, sugar and pulse crops. It is an essential constituent of many proteins, enzymes and certain volatile compounds such as mustard oil. It hastens root growth and stimulates seed formation. It is essential for the synthesis of certain aminoacids and oils. It can be called as master nutrient for oilseed production.
The deficiency of sulphur leads to slow growth with slender stalks, nodulation in legumes may be poor and nitrogen fixation is reduced. The young leaves turn yellow and the root and stems become abnormally long and develop woodiness. In case of fruit trees, the fruits become light green, thick skinned and less juicy. Sulphur deficient plant produces less protein and oil.
Micronutrients
Micronutrient elements are required by plants in very low concentration suggests that they all function as catalyst or atleast closely linked with some catalytic process in plants. Micronutrient elements include boron, copper, zinc, iron, manganese, molybdenum and chlorine.
Boron helps in cell development by its influence on polysaccharide formation. It regulates translocation of sugars across membranes and polyphenolase activity. Iron is a constituent of cytochrome, haem and non-haem enzymes. Perhaps the best known role of iron is its catalytic role in enzyme activity.
Copper, zinc and manganese are components of certain biological oxidation-reduction systems. Manganese performs some function in photosynthesis, acts as regulator to the intake and state of oxidation of certain elements.
Zinc is concerned with the formation of Sulphydryl compounds such as cystein in the regulation of oxidation-reduction potential within the cells. Molybdenum is a constituent of nitrate reductase and nitrogenase enzyme and is associated with nitrogen utilization and in nitrogen fixation. Chlorine stimulates the activity of some enzymes and influences carbohydrate metabolism.
Inserting or drilling or placing the fertilizer below the soil surface by means of any tool or implement at desired depth to supply plant nutrients to crop before sowing or in the standing crop is called placement.
With placement methods, fertilizers are placed in the soil irrespective of the position of seed, seedling or growing plants before sowing or after sowing the crops. The following methods are most common in this category.
Plough - Sole Placement
In this method, the fertilizer is placed in a continuous band on the bottom of the furrow during the process of ploughing. Each band is covered as the next furrow is turned. No attempt is usually made to sow the crop in any particular location with regard to the plough sole bands.
This method has been recommended in areas where the soil becomes quite dry up to a few inches below the soil surface during the growing season, and especially with soils having a heavy clay pan a little below the plough-sole. By this method, fertilizer is placed in moist soil where it can become more available to growing plants during dry seasons.
Deep Placement of Nitrogenous Fertilizers
This method of application of nitrogenous and phosphatic fertilizers is adopted in paddy fields on a large scale in Japan and is also recommended in India. In this method, ammonical nitrogenous fertilizer like ammonium sulphate or ammonium forming nitrogenous fertilizer like urea, is placed in the reduction zone, where it remains in ammonia form and is available to the crop during the active vegetative period.
Deep or sub-surface placement of the fertilizer also ensures better distribution in the root zone and prevents any loss by surface drain-off. Deep placement is done in different ways, depending upon the local cultivation practices. In irrigated tracts, where the water supply is assured, the fertilizer is applied under the plough furrow in the dry soil before flooding the land and making it ready for transplanting. In areas where there is not too much of water in the field, it is broadcast before puddling. Puddling places the fertilizer deep into the root zone.
Sub - Soil Placement
This refers to the placement of fertilizers in the sub-soil with the help of heavy power machinery.
This method is recommended in humid and sub-humid regions where many sub-soils are strongly acidic. Due to acidic conditions the level of available plant nutrients is extremely low. Under these conditions, fertilizers, especially phosphatic and potassic are placed in the sub-soil for better root development.
Localised Placement
This method refers to the application of fertilizers into the soil close to the seed or plant.
Localised placement is usually employed when relatively small quantities of fertilizers are to be applied. Localised placement reduces fixation of phosphorus and potassium.
Bulk Blending
It is the process of mixing two or more different fertilizers varying in physical and chemical composition without any adverse effects.
For this formulation certain additional materials called 'Fillers' and 'Conditioners' are used to improve the physical condition of the mixed fertilizer. This mixed fertilizer should be applied as top dressing.
Liquid Fertilization
The use of liquid fertilizers as a means of fertilization has assumed considerable importance in foreign countries. Solutions of fertilizers, generally consisting of N, P2O5, K2O in the ratio of 1 : 2 : 1 and 1 : 1 : 2 are applied to young vegetable plants at the time of transplanting. These solutions are known as 'Starter Solutions'.
They are used in place of the watering that is usually given to help the plants to establish. Only a small amount of fertilizer is applied as a starter solution. The starter solution has two advantages.
The nutrients reach the plant roots immediately,
The solution is sufficiently diluted so that it does not inhibit growth.
As such a starter solution helps rapid establishment and quick early growth. There are two disadvantages of starter solution, if watering is not a part of the regular operation-extra labour is necessary and the fixation of phosphate may be greater.
Direct application of liquid fertilizers to the soil need special equipment. Anhydrous ammonia (a liquid under high pressure upto 14 kg per square cm. Or more) and nitrogen solutions are directly applied to the soil. This practice is very popular in the United States of America. Plant injury or wastage of ammonia is very little if the material is applied about 10 cm below the seed. If the application is shallow, nitrogen from ammonia will be lost. This method allows direct utilisation of the cheapest nitrogen source.
Straight and mixed fertilizer containing N, P and K easily soluble in water, are allowed to dissolve in the irrigation stream. The nutrients are thus carried into the soil in solution. This practice of fertilization is called "Fertigation". This saves the application cost and allows the utilization of relatively in expensive water-soluble fertilizers. Usually nitrogenous fertilizers are most commonly applied through irrigation water.
Foliar Application
This refers to the spraying on leaves of growing plants with suitable fertilizer solutions. These solutions may be prepared in a low concentration to supply any one plant nutrient or a combination of nutrients.
It has been well established that all plant nutrients are absorbed through the leaves of plants and this absorption is remarkable rapid for some nutrients. Foliar application does not result in a great saving of fertilizer but it may be preferred under the following conditions.
When visual symptoms of nutrient deficiencies observed during early stages of deficiency.
When unfavourable soil physical and chemical conditions, which reduce fertilizer use efficiency (FUE).
During drought period where in the soil application could not be done for want of soil moisture.
There are certain difficulties associated with the foliar application of nutrients as detailed below,
Marginal leaf burn or scorching may occur if strong solutions are used.
As solutions of low concentrations (usually three to six per cent) are to be used, only small quantities of nutrients can be applied in single spray.
Several applications are needed for moderate to high fertilizer rates, and hence
Foliar spraying of fertilizers is costly compared to soil application, unless combined with other spraying operations taken up for insect or disease control.
Soil fertility may be defined as the inherent capacity of soil to supply plant nutrients in adequate amount and in suitable proportion and free from toxic substances. There are two types of soil fertility viz.,
Inherent or Natural Fertility
The soil, as a nature contain some nutrients, which is known as inherent fertility. Among plant nutrients nitrogen, phosphorus and potassium is essential for the normal growth and yield of crop. The inherent fertility has a limiting factor from which the fertility is not decreased.
Acquired Fertility
The fertility develops by application of manures and fertilizers, tillage, irrigation, etc., is known as acquired fertility.
The acquired fertility has also a limiting factor. It is found by experiment that the yield does not increase remarkably by application of additional quantity of fertilizers.
Factors Effecting Soil Fertility
The factors that are effecting soil fertility may be of two types, i.e.,
Natural factors and
Artificial factors
The natural factors are those which influences the soil formation and the artificial factors are related to the proper use of land.
The factors effecting the fertility of soil are parent material, climate and vegetation, topography, inherent capacity of soil to supply nutrient, physical condition of soil, soil age, micro-organisms, availability of plant nutrients, soil composition, organic matter, soil erosion, cropping system and favourable environment for root growth.
Maintenance of Soil Fertility
Maintenance of soil fertility is a great problem of our farmers. Cultivation of particular crop year after year in the same field decreases the soil fertility. To increase the soil fertility, it is necessary to check the loss of nutrient and to increase the nutrient content of soil.
The following things must be properly followed for increasing the fertility of soil.
It is well known fact that in high rainfall areas, due to the leaching of bases, acids soils are formed, while in low rainfall regions, on account of arid and semi arid conditions, saline and alkali soils occur.
Thus soil vary in acidity or alkalinity. The soil reaction is indicated by pH scale. When Ca(OH)2 or lime is added to the soil, it will become alkaline.
Liming of Acidic Soils
Liming means addition of any compound containing Calcium alone or both calcium and magnesium, that is capable of reducing the acidity of the soil. Lime correctly refers only to Calcium oxide (CaO), but the term as applied in agriculture is universally used to include various other materials also, like Calcium carbonate, Calcium hydroxide, Calcium - magnesium carbonate (marl) and Calcium silicate slags.
The effects of liming on the soil and plants are as follows :
Lime neutralizes soil acidity,
Beneficial soil bacteria are encouraged by adequate supplies of lime in the soil,
Lime makes phosphorus more available,
Liming helps the availability of potash and molybdenum,
Lime furnishes two essential elements, namely calcium and magnesium (if lime is dolamitic) for plant nutrition,
Fertilizers are relatively safer than pesticides which exhibit toxic properties on living systems. However, all the quantities of fertilizers applied to the soil are not fully utilized by plants. About 50 per cent of fertilizers applied to crops are left behind as residues. Though, inorganic fertilizers are not directly toxic to man and other life forms, they have been found to upset the existing ecological balance. The nutrients escape from the fields and are found in excessive quantities in rivers, lakes and coastal waters.
Algae blooms occur when the nutrient load is high, and these smother other aquatic vegetation and also interfere with the oxygen regulation in the water bodies. This phenomena may lead to loss of fish. Among the major synthetic plant nutrients, nitrogenous fertilizers cause most harm. Contamination of the environment arises because not all the fertilizer applied is taken up by the crop and removed at harvest. In tropical climate the maximum recovery in dry land crops is 50 to 60 per cent and 40 per cent in rice because much of nitrogen is lost as ammonia into the atmosphere.
Eutrophication of water bodies due to higher nitrate and phosphate concentrations, increasing levels of nitrates in drinking water sources, accumulation of heavy metals such as lead and cadmium in soils and water resources are the principal causes of environmental concerns due to fertilizer use in agriculture. In the a national wide survey it was found that many streams and more than 20 % of wells contain 10 to 50 mg or even more of nitrates per litre of water. The contamination is caused by domestic sewage leaking to the ground water. The nitrates in drinking water can lead to several ailments. Blue - baby syndrome in infants and gastric and other forms of cancer have been related with nitrates in drinking water or diet.
Another hazard associated with excessive use of fertilizers is the gaseous loss of nitrogen, into the atmosphere. High doses of carbon dioxide and ammonia that escape into the atmosphere both from fertilizer manufacturing plants and soils affect human health. Further the oxides of nitrogen have been reported to adversely affect the ozone layer, which protects the earth from UV radiation and heating up of earth.
The oxides of nitrogen cause respiratory diseases like asthma, lung cancer and bronchitis. Arsenic, ammonia are waste stream components of nitrogen manufacturing plants while fluoride, cadmium, chromium, copper, lead and manganese are waste stream components of phosphatic fertilizer industry. If these waste stream of components are not properly disposed they cause harm to human beings and animals with contamination of air and water.
The keeping quality of perishables like vegetables and fruits get declined with excess use of fertilizers particularly nitrogenous fertilizers.
Use of fertilizer by the farmer for increased crop production depends almost entirely on its economics. This is usually done by reporting response per unit area or per unit nutrient applied. With a view to convince the farmer about the profitability of fertilizer use, cost benefit ratio is also worked out.
Almost all such calculations are based on evaluating the extra produce at the support/market price and deducting the cost of fertilizer only at the statutory prevailing rates.
Due to high cost of commercial fertilizer marketed in India, the question of economics of fertilizer use has assumed great importance. The fertilizer association of India, New Delhi, therefore, organised series of group discussions on "Economics of Fertilizer use" during 1975. The recommendations of these group discussions are listed below,
Uniformity of approach in studying the economics of fertilizer is essential.
The fertilizer recommendations should be based on soil test values.
Balanced use of fertilizer should be advocated for better economic returns.
Use of nitrogenous fertilizer in split doses economises fertilizer use.
Micronutrient deficiencies should be corrected as and when needed.
Fertilizer schedule should be adopted for the whole crop sequence instead of a single crop.
To get the maximum benefit from the applied fertilizers, crops should be irrigated at the critical growth stages.
There is a certain hybrid rice which people of the Philippines called miracle rice. But Thailand exceed on this. Thai are known to have the best yields on rice. So better other tropical countries should get the example here. ____ Shads @ trilastin
There is a certain hybrid rice which people of the Philippines called miracle rice. But Thailand exceed on this. Thai are known to have the best yields on rice. So better other tropical countries should get the example here.
ReplyDelete____
Shads @ trilastin