Groundnut is a legume crop which is grown for its edible seeds. There are many other names of Groundnuts such as peanuts, manilla nut, goober and monkey nut. The botanical name of groundnut is Arachis hypogaea L. Groundnuts have a similar taste and nutritional profile to that of tree nuts such as almonds and walnuts. It is believed to have originated from Brazil in south America.
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It is classified as both a grain of legume as well as an oil crop. It is grown in many countries such as India, China, West Africa, USA, Sudan, Nigeria, etc. China is the largest producer of groundnuts in the world. Unlike other legume crops, the peanut pods grow underground. It was introduced in India in the 17th century by Jesuit Father.
Botanical name Arachis hypogaea L.
Kingdom− Plantae
Domain− Eukaryota
Phylum− Spermatophyta
Subphylum− Angiospermae
Family− Fabaceae
Genus− Arachis
Order− Fabales
The peanut plants are 30–50 cm tall. It is an annual herbaceous plant. It belongs to the Fabaceae family which also contains pea, legume and beans. It harbors symbiotic nitrogen-fixing bacteria in their root nodules.
The leaves of groundnut plants are 1–7 cm long and are 1–3 cm in diameter. These leaves are nyctinastic in nature, that is, they close at night.
The groundnut flowers are yellowish-orange in color and are about 1–1.5 cm in size. These flowers only last for a single day. They are borne in axillary clusters on stems above the ground.
For groundnuts, the fruit development happens by an unusual and rare process called geocarpy.
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After fertilization a short stalk at the base of the ovary elongates and forms a peg. A peg is a thread-like structure which grows down into the soil, due to which the fruit develops underground. The groundnut pods are also called legumes. These pods can have an approximate size ranging from 3–7 cm. These pods usually have one to four seeds.
The peanut fruits have many parts.
The first is a shell which is the outer covering. This shell mainly consists of mesocarp that has many large veins traversing through its length. It is in contact with soil.
There are two cotyledons which are the main edible parts. The edible seeds are covered in a brown paper-like covering known as seed coat.
There is an embryonic root at the bottom of the cotyledon known as Radicle. It also has an embryonic shoot called plumule that crops up from the radicle.
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Well drained, light sandy soil with a pH ranging from 5.9–7 is considered best for groundnut cultivation. Soil salinity greatly affects groundnut cultivation. Clay and heavy soils should be avoided as they interfere with the penetration of peg. The groundnut crops fix nitrogen in soil and thus improve the soil fertility. These are valuable in crop rotation. Rotation results in lesser weeds and pests in groundnut crops and thus improving the yield. In some places the groundnut crops are cultivated in a three-year rotation. For good groundnut yield, the soil should have adequate levels of phosphorus, potassium, calcium, magnesium, and micronutrients.
The groundnut crops develop well in warm weather. Groundnut is a rainy season crop and does not require much irrigation. It can survive with only 350 mm of water. The ideal water for best yield is 500 mm.
Flowering, peg formation, and pod development are critical stages of groundnut crop. During these stages soil moisture plays a very important role. Drought and high temperature have a very negative effect on the crop yield.
The quality of seeds is a very important factor in cultivation. The seed pods are shelled with hands about two weeks before planting. The hand shelling is done to ensure least damage to the seeds. The peanuts seeds are sown approximately 5 cm deep. It is usually sown in flat beds with 30 cm x 10 cm spacing.
The seeds require treatment with fungicides. Doing Rhizobium culture on seeds is also important. The groundnut fields should be kept free from weed for good yield.
In case of drought, irrigation should be provided for good quality yield. Pests such as pod borers, aphids and usually affect the groundnut crops. They also suffer from disease such as cylindrocladium black rot, charcoal rot and Early leaf spot, etc.
The harvesting time depends on the growing conditions as well as the groundnut cultivar. For the subspecies A. h. fastigiated, it is about 90–130 days after planting while for the subspecies A. h. hypogaea types, it is around 120–150 days after planting
The harvesting time is important for maximizing the yield. If we harvest too early then many pods will be unripe; while harvesting too late will result in pods snapping off at the stalk and getting lost in the soil. During harvesting, the entire plant along with most of its roots should come out of the soil.
Traditionally, the groundnuts were pulled and inverted by hands. Nowadays, a lot of harvesting is carried out with machines.
The machines cut off the main root of the groundnut plant by cutting through the soil just below the level of peanut pods.
Machines get the plant out of the soil and invert the bush.
The plant is put upside down for 3–4 days on the ground so that the moisture is dried up a little.
The peanuts are then threshed, which includes removing the pods from the bush.
The peanut must be dried properly before storing. They must always be stored in dry conditions.
Peanuts are consumed in many ways. Dry roasting of peanuts in a shell is very common.
Boiled peanuts are also a very popular snack.
They are also eaten as a fried snack.
The ground dry peanuts are roasted to make peanut butter.
Peanut oil which is extracted from the peanuts has a very mild flavor. It has a high smoke point.
Nowadays the peanut flour has also become very popular.
The table below explain the nutritional content present in 100 grams of peanuts −
| Energy | 2,385 kJ |
| Fat | 48 g |
| Carbohydrates | 21 g |
| Protein | 25 g |
| Calcium | 62 mg |
| Iron | 2 mg |
| Magnesium | 184 mg |
| Potassium | 332 mg |
| Phosphorous | 336 mg |
Peanuts are an excellent source of protein and also contain vitamins and minerals, but they should not be eaten in excess, due to their high fat content.
Peanuts get spoiled and get infected with mold fungus Aspergillus flavus if the moisture is high or the storage conditions are poor.
Q1. What is the botanical name of groundnut?
a) Arachis hypogaea L.
b) Juglans regia
c) Prunus dulcis
d) Carya illinoinensis
Ans: a
Q2. Which of the following is the correct botanical family of groundnut?
a) Anacardiaceae
b) Fabaceae
c) Rosaceae
d) Juglandaceae
Ans: b
Q3. What is the approximate height of groundnut plants?
a) 5 – 10 cm
b) 10 – 20 cm
c) 30 – 50 cm
d) 60 – 100 cm
Ans: c
Q4. What is the correct name of the edible part of groundnut?
a) Dicotyledonae
b) Plumule
c) Fagales
d) Cotyledons
Ans: d
Q5. Which of the following is the most suitable pH range for groundnut cultivation?
a) 1–3.5
b) 3.2–5
c) 5.9 – 7
d) 7.9–12
Ans: c
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