Everything you need to know about groundnut cultivation, harvest and production. Learn about:- 1. Introduction to Groundnut 2. Climate Required for Cultivating Groundnut 3. Growing Seasons 4. Soil 5. Field Preparation 6. Dormancy 7. Sowing Time 8. Manure and Fertilizers 9. Water Management 10. Weed Management 11. Use of Hormones 12. Plant Protection 13. Cropping Systems and Few Others.
Contents:
- Introduction to Groundnut
- Climate Required for Cultivating Groundnut
- Growing Seasons of Groundnut
- Soil Required for Cultivating Groundnut
- Field Preparation of Groundnut
- Dormancy in Groundnut
- Sowing Time of Groundnut
- Manure and Fertilizers of Groundnut
- Water Management of Groundnut
- Weed Management of Groundnut
- Use of Hormones in Groundnut
- Plant Protection of Groundnut
- Cropping Systems of Groundnut
- Intercropping of Groundnut
- Harvesting and Threshing of Groundnut
- Drying and Storage of Groundnut
- Yields of Groundnut
- Varieties of Groundnut
1. Introduction to Groundnut:
It is an important food, feed and oilseed crop. Groundnut is cultivated for its kernel that is rich in oil and protein. In India, 80% of the total produce is used for oil extraction, 11% as seed, 8% for direct food uses and 1% is exported. One issue with the use of peanuts for human food is the peanut allergy.
Groundnut seeds are nutritional source of vitamin E, niacin, falacin, calcium, phosphorus, magnesium, zinc, iron, riboflavin, thiamine and potassium
Some individuals have severe allergic reactions to tiny amounts of peanut, and these reactions can result in anaphylactic shock. Cultivation of any crop must accrue maximum benefits to the grower not only in terms of the returns but also other indirect benefits associated with that crop.
2. Climate Required for Cultivating Groundnut:
Groundnut is predominantly a crop of tropics but it is now grown throughout the tropical and sub-tropical countries and continental parts (warm parts) of temperate countries of the world. The limit of present commercial production is between latitudes 40°N and 40°S and is grown up to an altitude of 1050 meters. The optimum temperatures for growing groundnuts range from 25-35°C, temperature below 20°C retard growth and development.
Practically no growth is observed below 13.3°C and this is the lower critical temperature for groundnut. Reproductive growth is found to be greatest at temperatures between 24°C and 27°C. Reproductive growth is adversely affected at temperatures above 35°C due to the effect on pollen viability. Highest growth rate of pods is at soil temperature between 30°C and 34°C. Groundnut is a C3 plant and light influences both photosynthesis and respiration.
For maximum photosynthesis and high yields, clear cloudless days are beneficial. It is considered to be a day length insensitive plant. Low light intensity prior to onset of flowering slows vegetative growth. Low light intensity during rapid growth period increases the height and length of stems but decreases leaf weight and flowering.
Although groundnut is drought tolerant, good performance is strongly linked to adequate soil moisture content at sowing time, followed by well-distributed rainfall. Early maturing small-seeded varieties require 300- 500 mm while the medium to late maturing large-seeded varieties need 1000-1200 mm rainfall.
Well distributed rainfall throughout crop. Cycle is more important than total rainfall. The crop requires intermittent light showers with bright sunny days for flowering and their subsequent development.
Heavy rains and wet weather at harvest time cause germination of kernels in the pod in Valencia and Spanish bunch cultivars besides interfering with proper drying of the produce and reducing the quality. Ground nut crop can neither withstand frost nor prolonged dry spells or waterlogging. It needs abundant sunshine and high temperature to give good yield of pods.
3. Growing Seasons
of Groundnut:
Groundnut is generally sown round the year in India in following seasons:
1. Monsoon (Kharif):
About 85 % of groundnut in India is sown in the kharif season under rainfed conditions.
2. Winter (Rabi):
Groundnut is sown in limited area during rabi season where winter is not severe and night temperature do not fall below 15°C. Normally this crop is taken in rice- fallows to utilize residual soil moisture after the harvest of rice or with limited irrigation. Rabi groundnut is prevalent in coastal regions, river deltas of Krishna, Godavari and Cauvery and in other irrigated areas of T.N. and A.P.
3. Summer:
Groundnut during summer is grown in Orissa, T.N., A.P., Karnataka, Gujarat and Maharashtra under irrigated conditions. Summer crop gives more yields and high oil content in seeds than kharif, due to favourable climatic conditions for the growth and development of crop and low incidence of pests and diseases. Higher temperature coupled with higher light intensity leads to production of higher levels of enzymes in the leaf which facilitate greater photosynthetic activity.
4. Spring:
Groundnut in spring is grown in U.P., Punjab, Chhattisgarh and West Bengal under irrigated condition.
4. Soil Required for Cultivating Groundnut
:
The ideal soil for groundnut production is a well-drained, light-coloured, loose, friable, sandy loam soils that facilitate penetration of the pegs after pollination, and easy digging without pod loss. Soils well supplied with calcium and a moderate amount of organic matter is suitable for the growth and development of crop.
However, it can be grown on a wide range of soil types. It is largely cultivated on red loams (light and heavy) of varying depths. More than 50% of bunch groundnut and 80% of spreading groundnut are grown on sandy, sandy loam, loam, mixed red and black soils in India. Sandy loam soils are more suitable than clayey soils since they are more easily penetrated by roots and pegs and also allow easier percolation of rainfall. Harvesting operation also becomes easier on such soils.
Fine textured soils and those containing more than 2% organic matter are not preferred due to difficulty in harvesting and staining of pods. Groundnut plants are sensitive to salinity and high soil acidity (pH <5) could induce magnesium or aluminium toxicity. In this type of soil, calcium should be added to maintain the pH above 6. Yellowing of the leaves and blackening of parts of pods occur at pH 7.5 to 8.5. The optimum soil pH for groundnut is 6.0 to 6.5, but a range of 5.5 to 7.0 is acceptable.
5. Field Preparation
of Groundnut:
A good seed bed has a great significance for successful groundnut cultivation as it allows early root penetration and easy pegging and pod formation. Removal of crop residues that spread diseases and harbor pests is important.
For light soils, this type of cleaning should be followed by a shallow raking after the first light rains. This eliminates early weeds and breaks up the soil surface. In wetter area or with heavier soils, fields must be ploughed at the beginning of the season to suppress weeds and break up the soil which must then be refined by harrowing.
Groundnut requires a fine seed bed which can be obtained by ploughing with M.B. plough, followed by 2 cross harrowings at optimum soil moisture to secure good surface tilth to depth of 15 cm. Follow planking after each ploughing to conserve soil moisture.
Two ploughings followed by two harrowings are sufficient for optimum tilth in Maharashtra and Karnataka, while in M.P., Gujarat and Andhra Pradesh ploughing is done several times till fine tilth is obtained. The depth of ploughing must be about 20-30 cm. The field must be thoroughly levelled to avoid water logging in the season.
In high rainfall areas and in regions with shallow water table, modified land configurations of ridge and furrow and broad bed and furrow system are preferred to limit run-off or waterlogging. If groundnut is to be grown on ridges, the ridges should be made at or just before sowing, and should be flat-topped.
If the soil is dry when the ridges are being made, a light rolling after ridging will help make the seedbed firm. Application of chlorpyriphos 1% dust @ 25 kg/ha at final field preparation in termite prone soils is essential. If soil is acidic in nature, lime can be applied in acid soils under irrigated conditions. Apply lime as per soil test result or @ 1.25 t/ha at least one month before sowing.
6. Dormancy in Groundnut
:
Dormancy in seed may be attributed due to impermeability of the seed-coat to water, mechanically resistant seed-coats, incompletely developed or rudimentary embryos, etc. Dormancy in groundnut is a varietal character, as it is present in Virginia types while absent in Spanish and Valencia types.
Lower level of hydrolases like amylase and protease during seed development may be responsible for seed dormancy. The non-dormant seeds germinate immediately after maturity. The dormant seeds usually require a resting period of about SOTS days before maximum germination can be obtained.
Thus, the seeds of the kharif crop cannot be used for raising the rabi or summer crop. Dormancy can be broken by the use of Ethrel or by storing seed along with ripening bananas for 3-4 days in sealed air tight containers. The evolution of ethylene by the embryo is an essential pre-requisite for germination.
Dormant seeds may lose dormancy if digging is delayed and the pods are allowed to remain in the soil after maturity. Dormancy in groundnut seed is not much of problem as it will usually wear-off in storage before the next planting season. But, lack of dormancy in Spanish and Valencia types can cause vivipary in some areas when rain delay harvesting.
The bunch type of groundnut is generally sown during kharif season as rainfed crop and in summer season as irrigated crop. When crop reaches at maturity during kharif invariably rains occur and seeds in the pod start germinating affecting seed yield and its quality.
This problem is severe, especially in black cotton soils having more moisture holding capacity. Foliar spraying of 250-1000 ppm of Malic hydrazide at 60 and 75 DAS induces seed dormancy to an extent of 60-80 percent.
7. Sowing
Time of Groundnut:
In groundnut, sowing time is the most important non-monetary input influencing productivity. Time of sowing assumes greater importance in realization of higher yields. Sowing date is linked to rainfall distribution in the area and length of the crop season. Soil moisture must be sufficient to guarantee good germination. Seeds must not be sown immediately after heavy rains since they may imbibe too much water, which causes rotting.
This also results in excessive soil compaction, which may hinder germination. It is a predominantly rainfed kharif crop. Results obtained from All India Coordinated Research Project (AICORP) research revealed that in most parts of the country, sowing should be done between the first week of June and the last week of July. Delay in sowing by one week results in considerable yield losses. The sowing of rainfed kharif crop depends on onset of monsoon, and generally sown from June to July.
Under irrigated conditions of north, the crop is sown from April-July. In general early sowing improves yields (significant delay in sowing can reduce yield by 50%) and seed quality. For Rabi groundnut in south, raised on residual moisture, the optimum time of sowing is November.
As an irrigated summer crop, December-January sowing is ideal in the south, whereas for West Bengal, mid-February is optimum. In north-west plains zone, first fortnight of March is optimum for sowing.
Selection of Seed and Decortication:
Good seed is the foundation for high yields. Without good seed it will not be possible to establish optimum stands of healthy plants. Purity, good viability, bold, uniform size and free from diseases is the main characteristics of good seed. The quality of seed depends on the conditions during the development of pod and kernel, method of curing and storage conditions.
Decortication or removal of kernels from the pod by hand pressing is a tedious job. Use manually operated rotary or oscillating type decorticator to reduce the drudgery of the worker and the labour requirement. Power operated decorticator-cum-cleaner may be used in areas where power is available.
Healthy and well developed pods should be selected and pods intended for sowing should be hand-shelled (about a fortnight before sowing) and sorted in order to eliminate skinned, immature, moldy and small seeds. Pods shelled long before sowing time are liable to suffer from loss of viability and storage damages. Untreated seeds if used for sowing leads to poor germination due to the incidence of seed borne diseases like collar rot, seedling rot, root rot which results in poor plant population and low yields.
Seed treatment may be done with the mixture of carbendazim 0.1% + thiram 0.15% or with vitavax power (0.15%). Add sodium or ammonium molybdate @ 3g/10 kg kernel along with bacterial culture. About 1.5 kg of rhizobium culture would be required to treat the seeds for one hectare.
The seeds can also be treated with biological fungicide “Trichoderma viride” (Ecofit) 4 g powder/kg dry seed. For slurry seed treatment, take small quantity of water @ 10 ml/kg seed and mix 4 g Ecofit and give thorough coating on seeds and air dry before sowing. For soil application mix 2.5 kg Ecofit with 100 kg farm yard manure and broadcast over one hectare area.
Optimum soil moisture at the time of application ensures best results. One day before sowing the seed, treat the seed with Bradyrhizobium culture @ 5 g/kg seed. For better results use rice glue as a carrier. Seed should be inoculated with proper strain of Rhizobium culture, particularly in those fields, where groundnut is to be raised for the first time. Rhizobium culture treatment should be taken up after 7 days of the seed treatment with fungicides.
Seed rate depends on characteristics of variety, season, seed quality, planting density and availability of water for irrigation. The weight of seeds in shell required to sow one hectare is called the seeding rate. For bunch type 100-125 kg/ha seed is required. Spreading valentia types need wider row spacings, thus less seed will be required (87-100 kg/ha).
The seed rate is calculated as follows:
One of the critical factors limiting yields of groundnut is low plant population. Research indicates that yields are increased mainly by reducing spacing between rows. When moisture is a limiting factor, the spacing between the rows has to be adjusted to the amount of moisture available.
Changes in intra-row spacings have less effect on yields than changing the spacing between the rows. Spanish bunch type of groundnut is grown over 70% of the area. In bunch types, most of the pods are formed within a radius of 10 cm, from the tap root.
Thus, 10 cm is optimum plant to plant spacing with a row to row distance of 30 or 22.5 cm. This gives an optimum plant population of 3, 33 lakhs and 4.44 lakhs plants/hectare. However, under limited moisture conditions and in soils of poor fertility, it is necessary to give 15 cm spacing between plants within a row.
The semi-spreading and spreading types are spaced at 45 and 60 cm between rows and 10 and 15 cm between plants, giving an optimum plant population of 2.22 lakhs plants per hectare. Under irrigated conditions, plant population can be as high as 250,000 plants/ha.
In the winter/summer season, bunch varieties grown at a seed rate of 150 kg/ha is optimum. The most common spacing recommended for Spanish bunch type is 30 x 10 cm, this is also recommended to establish a plant population of 440,000 per ha.
The most common spacing recommended for bunch varieties is 30 x 10 cm, and 45 x 10 cm for semi- spreading/spreading varieties thereby maintaining a plant density of 0.333 and 0.222 million plants/ha respectively in both habit groups of groundnut.
The method of sowing groundnut followed in India can be grouped into three categories:
(i) Seed Drill:
Groundnut is mostly sown under rainfed conditions with a seed drill. The seeds are either directly sown through the fixed hopper (seed bowl) or through loose hoppers attached to draw tubes which are in turn loosely tied with ropes to coulters.
A double seed bowl seed-drill is also used for sowing. The depth of placement of seed is adjusted by adjusting hitching of the bullocks or in tying the seed drill. Now a days, mechanical seed drills are also used, in which the desired spacing (row x plant) can be maintained.
(ii) Sowing in Furrows:
The seeds are dropped by hand in furrows formed by the country plough. Seeds are also dropped in the furrows through a tube attached to the plough by a rope. The depth of planting is difficult to regulate in this method of sowing and usually the stand of the crop is not uniform.
(iii) Hand Dibbling:
In case of irrigated crop, dibbling seeds on ridges prepared by plough is preferred. Dibbling seed with hand is practiced mostly in irrigated area. It is laborious and time consuming. The seed rows are opened by a seed drill or tyne hoes and the seeds are dibbled in the rows. Even under irrigated sowing can be done using a seed drill when the soil is dry and then irrigation can be given after the border or check basins are formed.
In either of the cases, the depth of sowing should be 5-8 cm in light soils and 4-6 cm in other moderately heavy to heavy soils. Some of the improved techniques of groundnut cultivation are also recommended.
Criss-Cross Sowing:
In this method, total seed lot is divided into two equal parts, first part of the seed is sown in one direction adopting recommended row to row spacing and then remaining half is sown in perpendicular to first direction by adopting same row spacing. It maintains optimum plant population because of uniform seed distribution. It gives about 18% higher yields and may be useful mostly where groundnut succeeds rice.
Paired Row System:
Paired row planting has been found advantageous over wide row-set furrow cultivation system followed at Saurashtra region of Gujarat. This system also doesn’t require any extra monetary input. Seeds required for one single row are distributed in two rows with a distance of 22.5 cm between two rows of a pair and 45 cm between pair. It increases pod yield by 20-27 percent.
Broad-Bed and Furrow Method:
Adoption of raised bed and furrow system of cultivation as developed by the ICRISAT (International Crops Research Institute for Semi-Arid Tropics) has been found advantageous over the flat bed system particularly in rain shadow areas or in high rainfall areas having deep vertisols where drainage of excess water is a problem. In this system moisture, stored in the furrows, could be utilized effectively.
In this method after every 3 or 4 rows of groundnut spaced at 30 cm, one row is left blank which can be used as irrigation or drainage furrow and in between two furrows, the bed is raised by about 10-15 cm. This method gives higher pod yield over traditional flatbed system of cultivation.
Groundnut is normally sown in flat beds adopting a spacing of 30 x 10 cm. The set- furrow system of groundnut cultivation is still followed by the farmers of Saurashtra region of Gujarat. In this system, same furrows (90 cm) are used year after year for groundnut cultivation.
8. Manure and Fertilizers
of Groundnut:
Groundnut is a heavy feeder of soil nutrients. Being a legume and an oilseed crop, it has greater requirement for sulphur, phosphorus and calcium. It has unique capability of absorbing about 75% of S and Ca through the gynophores and developing pods. These important nutrients can be supplied either through manures and fertilizers. A reasonable level of organic matter must be maintained in the light, weakly structured soils where groundnuts are grown.
The groundnut plant has an extensive root system that allows it to explore a large volume of soil and therefore benefit from organic manure residues from the preceding cereal crop. Application of well decomposed FYM or compost @ 6 to 12 t/ha, depending upon the type of soil should be applied one month before sowing and be incorporated into the soil.
Besides supplying nutrients, it will reduce soil crusting/compaction and enhances water holding capacity of the soil. On an average groundnut crop yielding 1.0 t/ha removes about 170 kg N, 30 kg P2O5, 100 kg K2O, 39 kg Ca and 15 kg of Sulphur.
Therefore, nutritional needs of the groundnut must be satisfied to attain maximum yield. The N requirement of groundnut is not high due to biological N fixation, but it needs a starter dose of 10-20 kg (rainfed) and 10-30 kg N/ha under irrigated condition.
Seed inoculation with effective Rhizobium strain in combination of starter dose of N is necessary for better growth and development of plant. Ammonium sulphate is preferred to urea as a source of N due to S content. The N should be applied at the time of sowing or 3-4 days prior to sowing and incorporated into the soil. The fertilizer should not come in contact with the seed.
Groundnut responds to phosphorus well when the available P in the soil is less than 35 kg P2O5/ha. Phosphorus is a constituent of enzymes, phospholipids and proteins. It leads to early flowering and pegging. Application of phosphorus @ 20-60 kg P2O5/ha is beneficial depending upon soil type, moisture availability and crop rotation. Among the different sources of P fertilizer, single superphosphate is the best source, as it contains besides phosphorus (16%), calcium (19.5%) and sulphur (12.5%) which are essential for groundnut.
Phosphorus is required from the early stage of the crop growth to maturity. It is applied before sowing. Phosphorus fertilizer should not come in contact with the seed as it affects germination. Placement of P fertilizer is important since conversion of phosphorus into unavailable form is high and movement of P in the soil is limited. Thus P fertilizer should not be broadcast. Localised application of P fertilizer in a band in seed rows and placement about 5 cm below seed is beneficial. North Indian soils are normally rich in potassium.
Response to potassium can be obtained in the soils with less than 150 kg of available K2O/ha. Under rainfed and irrigated conditions 40 and 70 kg K2O/ha, respectively is recommended depending upon the available K2O status of the soil. Potassium is needed by the crop from early stage of its growth to maturity.
Potash fertilizer is also applied before sowing as a band placement in the seed row 5 cm below the seed. Fertilizer schedules for different agro-climatic zones/states have been worked out based on the experiments and recommended to the farmers accordingly.
About 10-25 kg of nitrogen, 25-50 kg of phosphorus (P2O5), and 0-50 kg of potassium (K2O) per ha have been found adequate for kharif groundnut. Ammonium sulphate for nitrogen and single super phosphate are the recommended fertilizers. Full dose of phosphorus and potassium and half of the nitrogen have been recommended for soil incorporation before sowing. The remaining half of the N should be applied 30-40 days after sowing.
Adequate calcium is absolutely essential to produce high yield of good quality nuts. Calcium must be added to slightly acidic soils to correct the pH and improve the quality of the seeds. Severe calcium deficiency leads to a high percentage of aborted seeds (empty pods or “pops”) and mild deficiency causes ‘black heart’. Calcium is barely translocated across the leaves, and should therefore be applied near to the fruiting zone (as a side dressing) at the onset of pod formation.
Sulphur is also important for the synthesis of fat. It helps in biological oxidation reduction processes. Sulphur deficient plants have low chlorophyll content. Acid soils are very poor in sulphur. An application of sulphur especially in Rajasthan and Uttar Pradesh states has been reported to be beneficial. Apply well powdered gypsum @ 250 kg/ha close to the base of plants at 20-25 DAS on either side and incorporate in the soil, so that it remains in top 3 cm soil.
This is required because calcium has to be supplied to the developing pods independently as movement of Ca from vegetative parts to the pods through gynophore is limited due to narrow xylem vessel in the gynophore. This will improve number of pods and pod filling. Apart from 22.3% calcium, gypsum also supplies 18.5% sulphur to the soil. However, gypsum is not required when SSP or Ammonium sulphate is used as it also supplies sulphur.
Groundnut is mostly cultivated in light textured soils like loamy sand, sandy loam and loam. A good response to micronutrient application has been observed in some of the major states. Micro-nutrients such as boron are lost from these soils through leaching due to percolation or due to repeated irrigation.
Availability of boron and molybdenum in acidic to moderately acidic soils is restricted due to precipitation with oxides of iron and aluminum. Boron deficiency in groundnut causes pollen abortion, hollow heart disease and restricted development of gynophore.
Pollen abortion develops sterility due to which more than 50 % flowers do not bear pod. Hollow heart disease in groundnut is the depression of inner walls of kernel with the development of black colour.
Among micronutrients, deficiency of zinc (in sandy and sandy loam soils of Andhra Pradesh, Tamil Nadu and Punjab), iron (in vertisols of Gujarat, Karnataka, Maharashtra) and boron (in Tamil Nadu and Maharashtra) are encountered by groundnut crop. Application of these nutrients have been found to improve yield significantly.
In such soils, soil application of 25 kg ZnSO4/ha and 12.5 kg FeSO4/ha at sowing has been recommended for better crop performance. Soil application of 15 kg borax/ha along with other NPK fertilizers behind the plough at sowing produces 25-30% higher yield. Boron can also be applied as foliar spray of 0.1% borax solution.
Molybdenum deficiency decreases nitrogen fixation in groundnut as a result of which nitrogen demand of groundnut increases. The seed treatment with ammonium molybdate @ 3 g/10 kg kernel along with rhizobium culture increase pod yield. Application of nutrients in balanced proportion is essential for obtaining higher yields considering antagonistic and synergistic effect among the nutrients.
9. Water Management
of Groundnut:
Groundnut is predominantly a rainfed crop with only 17.6% of its total acreage under irrigation. This irrigated area is mainly in rabi and summer seasons mainly. High yield and quality production is ensured using an irrigation programme adapted to crop demand at each development stage. Groundnut crop requires on an average 400 to 450 mm of water.
The important growth period of groundnut includes establishment (10-20 days), vegetative (25-35 days), flowering and pegging (35-50 days), pod formation (50-75 days) and pod development (75 90 days). In groundnut, the decrease in yield is proportionately less with the increase in water deficit during vegetative and ripening period and relatively large at flowering, pegging and pod formation stages. The most critical stages of irrigation in groundnut are flowering and pegging followed by pod formation.
The period of vigorous flowering is the period of greatest sensitivity to water stress. This stage is sensitive because of increased demand for water by the growing plant and the less efficient root system during flowering. Soil has to be soft at the peg development stage to allow the pegs to penetrate easily and the pod to develop. Pegging is sensitive to soil water level in the root zone (0-5 cm soil layer). A supplemental irrigation at pod formation stage results in successful rainfed groundnut cultivation.
Providing lifesaving irrigation during a long dry spell at critical growth stages increase yield by 50% in the states of Gujarat and Rajasthan and thereby stabilize groundnut production in the country. Adoption of raised bed and furrow system of cultivation as developed by ICRISAT has been found advantageous over the flat bed system particularly in rain shadow areas. This orientation results in 8-10 % higher pod yield over traditional flatbed system of cultivation.
Under irrigated conditions, besides a pre-sowing irrigation, supplemental irrigation should be given at critical stages based on rainfall distribution. In rabi and summer seasons, 3-4 irrigations are required. Irrigation should be given when 25% depletion of available soil moisture (DASM) occurs but when water supply is crucial, irrigation should be scheduled at 50% DASM in 0-15 cm of soil surface. After the crop is established, it is necessary to withhold irrigation for about 20 days and create stress and then give next irrigation.
This will encourage early flush of heavy flowering, root development and nodulation and checks excessive vegetative growth. Irrigation should be stopped one week before harvest so that quality of seeds does not deteriorate. The light irrigation may be given prior to harvesting so that entire pods from soil can be recovered.
The most suitable method of irrigation for groundnut is border strip method, though check basin method is followed more extensively. In light soils and water limiting regions, sprinkler irrigation is found suitable for water economy and higher productivity.
Good drainage should be provided for realizing good yields of groundnut. Present practice of flood irrigation aggravates problem and also makes it difficult for the penetration of pegs into the soil. Groundnut needs aeration in the rooting and pegging zones. Inadequate aeration results in abnormal respiration, which in turn inhibits root growth and retards metabolic function.
10. Weed Management
of Groundnut:
Groundnut cannot compete effectively with weeds, particularly at the early stages of development (3-6 weeks after sowing). Weeds cause enormous yield losses (30-70%) in groundnut owing to its slow initial growth and short stature.
The yield losses are more in bunch than spreading types. The major weeds commonly found in groundnut fields, among narrow leaf are Commelina benghalensis, Cynodon dactylon, Echinochloa colonum, E.crusgalli Dactyloctenium aegyptium, Digitaria sanguinalis, Panicum repens, Saccharum spontaneum, Sorghum halpense and broad-leaved includes Ageratum conyzoides, Amaranthus viridis, Celosia argentea, Euphorbia hirta, Trianthema portulacastrunm, Tridex procumbens, Phylanthus niruri, Chenopodium album, Solarium nigrum.
Grasses are the predominant weed species closely followed by broad leaved weeds and sedges in rainfed groundnut. The secretions of roots of the weeds like Cirsium arvense, Chenopodium album etc. could be a serious impediment in the early establishment of groundnut and thereby, could limit the absolute realization of groundnut yields if not controlled in time.
Cultural method of weed control is a common practice in groundnut. Crop rotation may reduce certain species of weeds. For effective control of weeds and to keep the soil loose for pegging, 2 hoeings or weedings are essential. The crop is given first hoeing at 20-25 days after sowing (DAS) and the subsequent at 40 DAS. Earthing up should be done simultaneously with hoeings which facilitates penetration of pegs.
Once pegging begins, soil disturbance should be avoided or kept to a minimum, so as not to interfere with the developing pods. Instead weeds at this stage can be controlled by hand-pulling. In view of the labour scarcity, expense and time involved, the use of herbicides either alone or in combination with cultural method to control weeds effectively has become a necessity.
The herbicides used for weed control includes fluchloralin @ 1.0-1.5 kg/ha or imazethapyr 50-70 g/ha in 800-1000 litres of water as pre-plant incorporation, while pendimethalin @ 1.0 kg/ha, nitrofen @ 1.0-2.0 kg/ha and alachlor @ 1.0-2.0 kg/ha as pre- emergence application.
The other pre-emergence herbicides like metalachlor @1 kg or oxyfluorfen @ 0.25-0.50 kg/ha can be used in 800-1000 litres of water along with one HW on 30 DAS has been found profitable. Post emergence spray of quizalofop ethyl 5 EC @ 50 g/ha or fluazifop butyl @ 150-250 g/ha at 20 to 30 DAS has been found promising for controlling grasses, especially Cynodon dactylon. Integration of herbicides with one or two hand weedings at 30 and 45 DAS controlled weeds efficiently and recorded higher pod yield of groundnut.
11. Use of Hormones
in Groundnut:
Groundnut usually suffers from two drawbacks – the first is that the crop being non- determinate keeps on flowering and production of pegs simultaneously until maturity, and the second is that the pods start germinating once after reaching physiological maturity.
As a result more than 50% of plant energy is lost in producing non-effective pods and germination of effective pods, if there is a rain or irrigation. Thus both the conditions lead to very poor yield and quality of the produce.
Application of MH (maleic hydrazide) near maturity results in inducing dormancy in the pods for about 20-30 days, which checks the germination of matured pods even if they get water.
Application of nepthalic acetic acid (NAA) in the form of planofix or vardhak at the time of flowering has been found to reduce excess vegetative growth and flowering period, ultimately resulting in more of effective pods/plant, test weight and yield/unit area. The most ideal time for hormone application in groundnut is 40 and 80 days after sowing and the best concentration is 20 ppm.
In Punjab, sequential spray of 2 growth regulators viz., indole acetic acid (IAA) and ethrel has been found to increase the yield, particularly of variety M 13. IAA @ 1.5 g/ha should first be dissolved in small quantity of alcohol/spirit (10-12.5 ml) and then mixed in 250 litres of water and spray on the crop 40- days after sowing. This spray should be followed by another spray of ethrel (40%) @ 15 ml in 250 litres of water/ha, 7-10 days after IAA spray. These sprays may increase the yield by 15-25 percent.
12. Plant Protection
of Groundnut:
Groundnut is susceptible to a number of pests and diseases that can cause considerable yield losses. Recommended protection measures against diseases and insect pests should be regularly followed during the cropping season.
Groundnut Production System of Groundnut:
There are four major groundnut production system. In rainfed areas there is a need for short and medium duration cultivars suitable for oil, food, and fodder use. In areas where supplemental irrigation is available, mostly medium-duration cultivars, while under high-input situations, medium-and long-duration cultivars are grown for confectionery and oil use. Under residual moisture production systems, the crop duration is short and uses are restricted to oil and food.
Agro-Ecological Regions of Groundnut Farming in India:
About 75 % of the groundnut area lies in a low to moderate rainfall zone with a short period of distribution. Though management practices of the crop have improved in recent years and the declining trend in yield has been arrested, there are wide fluctuations in yield due to rainfall and soil factors. Taking into considerations of the above factors the cultivation of groundnut has been demarcated into five zones based on soil factors, rainfall pattern, diseases and pest situations.
13. Cropping Systems
of Groundnut:
The groundnut fits into a wide range of farming systems. It can follow both cereals (maize, sorghum, pearl millet and sorghum) and root crops (cassava and sweet potatoes). Groundnut does well on virgin land or immediately following a grass fallow or a well fertilized crop such as maize.
Avoid groundnut-groundnut rotation to discourage the build-up of pest and diseases. Normally, groundnut is grown in rotation with wheat, gram, pea, barley etc. It is grown as mixed crop with maize, pearl millet, castor, sorghum and cotton.
Groundnut can also be followed by safflower, where early varieties are raised and moisture remains in the soil at the time of harvest. A sustainable system will involve the well planned alternate uses of the land through sequential cropping, intercropping, relay cropping etc. keeping groundnut as the central commodity of the system.
Intensive crop rotations of groundnut are Maize (summer season)-groundnut-gram/sarson, Groundnut-onion or garlic Mungbean-groundnut-wheat, Maize-groundnut-pea, Lobia-groundnut-wheat, Groundnut-wheat-mungbean/urdbean Groundnut-wheat, etc.
14. Intercropping
of Groundnut:
Area under kharif groundnut is not likely to expand any further in India. The most potent way of increasing the area is by finding a place for groundnut as an intercrop. This system gives some safety against weather calamities and helps in better utilization of farm resources. Some remunerative inter-cropping systems for different states have been recommended to increase obtainable per unit area and time.
The most suitable companion crops are sorghum, pearl-millet, maize (in case of cereals), red gram, black gram, green gram (in pulses or legumes), and sunflower, castor and sesame (in oilseeds). Groundnut based intercropping systems were evolved for different agro-climatic zones to minimize the risk factors associated with rainfed condition. The most promising intercropping systems identified in recent years are groundnut + sorghum (3:1), groundnut + pigeonpea (3:1), groundnut +castor (3:1), groundnut + soybean (1:1), etc.
15. Harvesting and Threshing
of Groundnut:
It is important to harvest groundnut at the right time, i.e. when the crop is mature. Flowering is indeterminate in the groundnut; therefore there may be a variable proportion of mature and immature pods at the end of the crop cycle. The harvesting of groundnut depends upon the type of variety grown.
Groundnuts are mature when 70-80% of the inside of the pods shells have dark markings and the kernels are plump, with color characteristic of that variety. Harvest the crop when plants turn yellow and leaves start drying, original seed colour develop on the kernel and the pods develop blackish streak inside the shell. If harvested prematurely, the kernels shrink upon drying, resulting in decreased shelling percentage, poor seed quality and lower oil content.
If harvested late, non-dormant varieties will sprout in the field, resulting in yield losses. Usually bunch type groundnut crop takes 110-130 DAS, runner types 130-150 DAS and once the majority of pods are mature, delay in harvesting results in substantial loss. In case of bunch types, the plants are harvested by pulling, whereas in spreading types, harvesting is done by spade or country plough.
Bullock drawn groundnut digger may also be used for uprooting. Moisture content of pods at harvesting varies between 35 and 40 % which needs drying upto 20-25 % for threshing. Groundnut stripper or power operated groundnut thresher can be used to remove the pods from the plants.
16. Drying and Storage
of Groundnut:
The primary objective of curing or drying, is to achieve a rapid but steady drying of pods in order to avoid aflatoxin formation. Harvested plants should be staked in the field or a few days to allow them to dry in the sun and air, before stripping the pods.
Then drying should be continued until the moisture content is reduced to 8-9%. This can normally be achieved by drying the pods in the sun for 6-7 days, taking care to cover them if it rains. If pods are exposed to the light for long time, both kernels quality as well as their germination got affected.
The storage of groundnut should be done at seed moisture content of 8-9%, relative humidity of less than 65% and a temperature of less than 30°C. Poor storage facilities may lead to fungal infection. For safe storage, metallic containers are better as compared to local mudbins and gunny bags. Safe storage period for groundnut kernel is about 2 months at 7% moisture and for groundnut pods it is about a year.
For seed purpose, special precautions are required during drying and storage to retain viability especially in case of produce from summer crop. Seed viability is impaired when pods are dried at 40°C or higher. Dry the uprooted plants under shade till the pods produce rattling sound. Store the pods in polythene lined gunny bags in a well-ventilated room.
Anhydrous CaCl2 @ 250 g/30 kg bag may be used as a desiccant. In storage, the stack base should be on raised stands. Stacks should not be more than 10 bags piled one over the other. The pile of bags has to be kept 4-5 feet below the roof and separated from the wall to allow free circulation of air.
Aflatoxin production in groundnut caused by the Aspergillus flavus group of fungi occurs mainly during post-harvest processing and storage. In India 81% of kernels are immediately crushed for oil, 12% as seed, 6% for edible use and 1% for export, and thus, aflatoxin is not a problem in the oil extraction.
However, aflatoxin is a concern in edible and for exportable commodities i.e. kernel, groundnut cake etc. The permissible limit of aflatoxin content is 6 ppb. Recently, bold to medium bold seeded genotypes resistant to invasion, colonization and production of aflatoxin by A. flavus have been identified for export purpose.
Pods are stripped at about 2 to 6 weeks after harvesting, when the pod water content stabilizes at around 10%. This operation consists of separating the pods from the vegetative parts of the plants (vines). In traditional farming systems, manual stripping is the rule. Pods are individually detached from the vines and therefore dry very quickly stabilizing at 6-8% moisture content.
The process results in a perfect quality product. This technique is used for the production of edible or confectionery groundnuts in order to minimize pod damage and contamination by Aspergillus flavus. However, stripping is most often done using sticks. These reduce the heap of groundnut plants into a mixture of chopped vines and partially broken pods that are then separated by winnowing.
17. Yields
of Groundnut:
By adopting improved technology, it is possible to obtain about 1.5-2.0 tonnes of pods/ha from bunch types and 2.0-3.0 tonnes/ha from spreading type varieties. The shelling percentage is 70%, whereas oil to nuts in shell is 28%, oil to kernels crushed is 40% and cake to kernels crushed is 60%.
Groundnut kernels, which are plentifully produced in India, are widely acknowledged as a rich and cheap source of vegetable protein, and if included in the daily diet, will help decrease the protein deficiency economically.
From a nutritional standpoint, groundnut is almost a class by itself amongst low priced food products. One gram of groundnuts supplies 5.8 calories of food. Compare this with 4 calories from sugar, 3.5 calories from whole wheat, 2.6 calories from bread, etc. The high caloric value of the groundnut is due to its low moisture content.
Groundnuts are rich in some vitamins, almost wholly lacking in others. In general, the members of the B-complex, especially thiamin, riboflavin and nicotinic acid are present in significant amounts. Groundnuts are also a good source of vitamin E, but amounts of vitamins A, C and D are negligible.
Even though groundnut is recognized as a palatable ‘poor man’s nut’ and is eaten and relished by all classes of people, its consumption in India has not kept pace with the increase in its production due to the fact that there is no organized agency for the regular supply of edible groundnuts or for processing it for consumption.
18. Varieties
of Groundnut:
Seed accounts for about 40 to 45% of the total cost of cultivation. Therefore, due care should be taken to select the most ideal variety to suit the local climate, geographical location and having high yield potential.
The varieties under cultivation fall into following habit groups:
(i) Bunch types have light green foliage, comparatively broad leaflets and mature easily. However, they are usually susceptible to tikka disease. These types preferred where rainfall the rainy season is short and also for irrigated crop in rabi and summer seasons. Where the soils have high clay content and harvesting is a problem, bunch types are preferred.
(ii) Spreading types usually have dark green foliage with smaller leaflets. These are usually late in maturity. These types are preferred under rainfed conditions where the rainy season is longer.
(iii) Semi-spreading types are intermediate between the bunch and spreading types. The area under this type of groundnut (Virginia bunch) is limited and confined to areas where spreading types are also grown.