Everything you need to learn about groundnut cultivation, production and growth.
Introduction to Groundnut:
Groundnut or peanut is a native of Brazil. It gradually spread to various other countries, namely, Peru, Argentina and Ghana and later to Jamaica, Cuba and other islands of the West Indies. The crop was introduced into India in the early part of the sixteenth century.
At present, the major groundnut-producing countries of the world are India, China, Nigeria, Sudan, Burma and USA. So far as India is concerned, the crop occupies about 7.5 million hectares annually and the production is about 6 million tonnes. The production in 1988- 89 is expected to rise to 8 million tonnes. Roughly, 70 percent of the total area and 75 percent of the total production in the country are concentrated in the states of Gujarat, AP, Tamil Nadu and Karnataka.
Groundnut (Arachis hypogaea L.) belongs to the sub-family, Papilionaceae of the family, Leguminosae. It is a low annual plant with an erect central stem and more or less procumbent laterals. In the “prostrate” types, all laterals are prostrate from the beginning. Stem are cylindrical and hairy. Leaves are alternate, stipulate and quadrifoliate.
Flowers develop either singly or in clusters of three in the leaf axils. They are orange-yellow in colour and typically papilionaceous and sessile. Calyx consists of 5 sepals, united to form a tube. Corolla of 5 petals is papilionaceous, inserted on the rim of the calyx tube, Standard broad and large; wings oblong and free; keel incurved and, beaked.
Stamens 10 is filaments connate into a tube and alternately long and short; two anthers sterile and eight fertile. The pistil consists of a single sessile carpel. Style long and filiform and carries a terminal stigma. Ovary is superior, unilocular with 2 to 3 ovules. After fertilization, the internode between the ovary and receptacle elongates and turns sharply downwards to the earth.
Normally, ovary begins its development only when the gynophore has buried it some 2 to 5 cm into the soil. Sometimes, it may swell when it fails to reach the ground, but in such cases the seed does not mature. Mature fruit large, oblong and indehiscent, with longitudinal and anastomosing ridges, giving a distinct reticulation to the surface. Usually, 1 to 3 seeds present in a fruit, which is externally constricted between the seeds.
Climate and Soil Required for Groundnut:
Groundnut is grown in both tropical and sub-tropical climates, up to an altitude of 1,000 metres. It can be cultivated successfully in areas, which receive a minimum rainfall of 500 mm and a maximum of 1250 mm. A well-distributed rainfall during the flowering and pegging of the crop is very beneficial. A groundnut crop cannot stand frost, long and severe drought or water logging.
While the crop can be grown on different types of soils, it does best on sandy loam, loam and well-drained black soils with good drainage.
Although as a kharif crop, groundnut is generally grown in the same area, year after year, it is rotated in certain areas with wheat, sorghum, pearl millet, gram, castor, paddy and cotton, and occasionally with potatoes, onions, chilies, etc.
Pulses like red gram, black gram and green gram or certain millets like sorghum, pearl millet or castor are sometimes grown in mixture with groundnut.
Cultivation of Groundnut:
Groundnut is cultivated mostly as a rain-fed kharif crop and is sown from May to June. In areas, where the monsoon is late, the crop is sown in August or September. As an irrigated crop, it is cultivated on a small scale between January and March and between May and July.
For raising a kharif crop of groundnut, the field is ploughed several times and the soil pulverized well with the onset of rains, in order to obtain a good tilth. Generally, the recommended doses of fertilizers are 6.25 tonnes of farmyard manure, 10-20 kg of nitrogen, 20-40 kg of phosphorus and 20-40 kg of potassium per hectare for the rain-fed crop and 12.5 tonnes of farmyard manure, 20-40 kg of nitrogen, 40-90 kg of phosphorus and 20-40 kg of potassium per hectare for the irrigated crop.
As Indian soils is rich in potassium, only nitrogen and phosphorus are usually applied, the former in two equal split doses, one before sowing and the other 30 days after sowing. Treatment of seed with Rhizobium culture is beneficial, particularly for lands, where groundnut is a newly introduced crop.
Only well-filled kernels are selected for sowing. They are treated with 5 g of Thiram or 3 g of Captan per kg of kernels. Sowing of seed in the case of kharif crop is generally done with a seed drill at a depth of 8-10 cm. Spacing adopted is not the same in different places. For spreading and semi-spreading varieties, the spacing between adjacent rows may vary from 30 to 60 cm and that within a row from 10 to 15 cm.
For the rain-fed bunch varieties, the spacing between rows varies between 20 and 30 cm and that within a row between 10 and 20 cm. In case the above spacing is adopted, the quantity of seed required per hectare will be 110 kg for the semi-spreading and spreading varieties and 120 kg for the bunch varieties.
In order to check weed-growth and also to keep the soil in a friable condition, the crop should be given one hand-weeding and one or two hoeing, the first one about 3 weeks after sowing and the second and the third ones about a fortnight and a month later. Control of weeds can also be done by the use of weedicides, Lasso or Tok. E-25.
No intercultural operation should be undertaken after the pegs (young fruits) have started going underground. Earthing up has been found to be a useful operation in the case of bunch types and semi-spreading types, because it facilitates maximum penetration of the pegs in the soil.
For irrigated groundnut, the frequency of irrigation depends on the texture of the soil. In case of prolonged drought during kharif, particularly at the pod-formation stage of the crop, irrigations will be of much help.
Harvesting and Yield:
The crop is harvested when the basal leaves become yellow, older leaves are shed, the kernels are full grown and the testa develops the proper colour. The bunch and the semi-spreading varieties are usually harvested by pulling out the plant by hand when there is sufficient moisture in the soil. The spreading types, on the other hand, are harvested by digging or ploughing the soil.
The harvested plants are left in the sun for a few days for drying and the pods are stripped thereafter. The pods are cleaned and dried properly in order to bring the moisture-content to 5 percent. They are then stored in gunny bags. The oil content of the seed varies from 44 to 50 per cent.
The average yield of unshelled pods of semi-spreading and spreading varieties under rain-fed conditions ranges from 1,200 to 1,400 kg per hectare, while that of bunch varieties from 800 to 1,000 kg per hectare. Under favourable conditions, the production may be considerably higher, up to 3,000 kg or more. The yield of kernels is roughly about 70-75% of the pods by weight.
Uses and Varieties of Groundnut:
The oil is edible and is extensively used as a cooking medium. It is used in the manufacture of hydrogenated vanaspati, margarine, soap, cosmetics, lubricants, illuminants, etc. The kernels are also eaten raw.
The groundnut varieties under cultivation may be classified into three different groups on the basis of their growth habit, namely, bunch (Spanish), semi-spreading (Virginia bunch) and spreading (Virginia runner). In the first group, the plants are erect and the pods are in clusters at the base of the plant and have non-dormant seeds.
In the other two groups, the branches trail partially or completely on the surface of the soil, possess pods all along them and the seeds are dormant. The varieties of these two groups usually yield heavier and mature later than those of the first group.
Some of the improved kharif varieties recommended for different states are indicated below:
Diseases of Groundnut:
The common diseases of groundnut are:
(i) Tikka leaf spot disease caused by Mycosphaerella berkeleyii and M. arachidicola, which can be controlled by spraying Brestan or Bordeaux mixture or 2% Ziram or Zineb.
(ii) Collar rot caused by Pellicularia rolfsii, which can be controlled by growing resistant varieties, by disinfecting the soil with Chloropicrin.
(iii) Rosette disease.
(iv) Mosaic disease, both caused by virus, which can be controlled by roguing out affected plants.
(v) Bunchy top disease.
(vi) Chlorosis disease, both caused by virus, which can be controlled by using virus-free seed and roguing out diseased plants.
Insect Pests of Groundnut:
The common insect pests, which attack the crop, are:
(i) Aphids (Aphis craccivora), which can be controlled by spraying 0.03% Dimethoate, Phosphamidon or Monocrotophos.
(ii) Leaf miner (Stomopteryx nerteria), which can be controlled by dusting 5% BHC or 4% Carbaryl.
(iii) Red hairy caterpillar (Amascata moorie and A. albistriga), which can be controlled by dusting 10% BHC (the early stage is easy to control).
(iv) White grub (Lachnoster- na consanguinea), which are difficult to kill, but the application of 10% Phorate granules, an expensive method, is reported to be effective.