Interesting facts about Groundnut/Peanut (Arachis hypogaea)
Groundnut is a versatile and economically significant plant that has played a prominent role in human history. It is the sixth most important oilseed crop in the world and the third most important source of vegetable protein. Groundnut is a cash crop providing income and livelihood to the framers. The plant originates in South America and has been cultivated for many centuries, providing sustenance, oil, feed, and a wide range of human health and soil health benefits.
The Groundnut or Peanut plant is scientifically known as Arachis hypogaea. It is a legume crop belonging to the family Fabaceae and the cultivated groundnut has two subspecies, hypogaea and fastigiate, in order these have two botanical varieties (var, hypogaea and var. aequantoriana). There is a large variation in plant morphology (pod and seeds) between these two subspecies [1]. The plant is self-pollinated with a cleistogamous flower (in which the pollen produced from within the flower pollinates only the stigma(s) of that flower). Still, natural hybridization can occur to a small extent in the presence of high bee activity.
The majority of commercially grown types are members of the botanical variety groups hypogaea (common name/market type: Virginia or runner), fastigiate (Valencia), and vulgaris (Spanish).
Groundnut plant information - morphology and environmental requirements
It is an annual crop that can reach about 30-50cm in height with a tap root system and several lateral roots. Depending on the cultivar and environmental conditions, flowering begins around 17-35 days after seedling emergence. After flowering, the plant's elongated stalks develop into pegs and bend towards the ground, later entering into the soil (positively geotropic), allowing the developing pods to bury themselves in the soil [2]. This unique feature gives the groundnut its name. The pod's tip faces away from the tap root in a horizontal orientation.
Cultivating groundnuts requires a well-drained field having sandy, loamy sand or sandy loam soil, which is free from soil-born diseases with at least 500mm of evenly distributed rainfall and ample sunlight. It can be grown as a sole crop, intercrop, and mixed crop in rainfed conditions. It can be grown as a sole crop if irrigation and residual moisture (rice fallows)are available. Plant growth and development are largely influenced by temperature, and the optimum air temperature suitable is around 25-30° C. Groundnut is cultivated as a sole commercial crop in countries such as the USA, Australia, Argentina, Brazil, China, and South Africa. This presents high inputs, large holding, availability of irrigation and mechanized or semi-mechanized cultivation, and high productivity. At the same time, this is the opposite in the countries of Asia and Africa with subsistence farming.
Depending upon the soil type, land slope, and irrigation availability, the groundnut can be cultivated in different methods. Such as ridge and furrows at 60 cm spacing ridges and sowing taken on both sides of ridges and broad bed (width of 60 cm, leaving 15 cm on either side for furrows) and furrows method to ensure optimal growth. The broad bed is covered with a mulching sheet for moisture retention in some places. Groundnuts are known for their nitrogen (100-152 kg/ha N) -fixing properties, and they add organic matter to the soil benefiting the soil and reducing the need for external fertilizers. Gypsum (Calcium Sulphate) can be applied 45 days after sowing to encourage pod formation and better pod filling. This can be avoided for calciferous affected soil.
Historical Significance of Groundnut
No one is certain of the precise origin of cultivated groundnut; it most likely began in the region of the eastern foothills of the Andes (southern Bolivia and northern Argentina). Genus Arachis is naturally restricted to Argentina, Bolivia, Brazil, Paraguay, and Uruguay in South America.
The Guarani region, Goias and Minas Gerais (Brazil), Rondonia and northwest Mato Grosso (Brazil), eastern foothills of the Andes in Bolivia, Peru, and north-eastern Brazil are the six recognized gene centers for cultivated groundnut in South America. This contributed to the greatest genetic diversity in Arachis. A secondary center of diversity can be found in Africa.
In the late 15th century, the Portuguese carried 2- seeded groundnut varieties from the east coast of South America (Brazil) to Africa, to the Malabar coast of south-eastern India, and possibly even to the far east. Spaniards brought 3-seeded Peruvian types (including hirsute types) from the west coast of South America via the western Pacific to Indonesia, China, to Madagascar; Groundnut was exported all over the world by the middle of the 16th century and came to North America from Africa (via the slave trade), the Caribbean islands, Central America, and Mexico; More than 114 counties presently grow groundnut; by the 19th century, it had become a significant crop in West Africa, India, China, and the USA.
Nutritional Value and Health Benefits of Groundnut
Groundnuts are very nutritional, making them valuable to a balanced diet to fight malnutrition. They are an excellent source of plant-based protein (25-28%) in kernels and oil (48-50%). In addition, the groundnut kernels provide many enhancing nutrients such as minerals – K, P, Mg, etc. Among these minerals is magnesium, which supports bone health and regulates blood pressure. Phosphorus, another essential mineral found in groundnuts, aids in energy metabolism and plays a vital role in maintaining healthy teeth and bones [2].
Groundnut kernels possess antioxidants and vitamins and are an excellent source of E, K, and B; and all the essential amino acids needed for growth and repair.
A 100-gram serving of groundnuts has around 560 kcal and contains around 25 grams of protein, making them a great alternative for vegetarians and vegans. These fats help lower bad cholesterol levels and reduce the risk of heart disease. Furthermore, it contains various beneficial plant compounds, such as resveratrol, flavonoids, and phytosterols. These compounds possess antioxidant and anti-inflammatory properties, which contribute to the prevention of chronic diseases, including cancer and diabetes.
Apart from groundnut kernels, postharvest haulms contain:
- 85-93% dry matter
- 6-20% crude protein
- 2-13% digestible protein
- 47-56% total digestible nutrients (TDN)
- 8-11 MJ/kg metabolic energy (ME)
- 1-3% fat
- 42-27% carbohydrate
- 22-38% crude fiber
- 9-17% minerals
- 0.3-0.7%- P
- 1.5-2.5% Ca
Therefore, The post-harvest haulm (leaves, branches, stems) are used as animal feed or else in compost production [3].
Diverse Uses of Groundnuts
The groundnut's versatility extends beyond its nutritional benefits. Groundnut seeds are widely consumed as raw, roasted, peanut butter, protein bar, chocolate, laddoos making, etc.
Groundnut oil, extracted from the plant's seeds, is used in cooking, frying, and salad dressings due to its mild flavor and high smoking point. The oil is also used in the production of margarine and as a base for cosmetic products.
Groundnut meal, a by-product of oil extraction, haulm, leaves, stems, and shells are essential components of animal feed. Its high protein content makes it an ideal supplement for livestock and poultry.
Furthermore, groundnut shells are used as boi-fuel, serving as a renewable energy source. The groundnut is indeed considered an ideal legume because each plant part can be reutilized for various purposes. Overall, the groundnut plant exemplifies the concept of sustainability and resourcefulness.
References:
- Krapovickas A and Gregory WC (1994) Taxonom ́ıa del ge ́nero Arachis (Leguminosae). Bonplandia 8: 1–186.
- Pasupuleti Janila, N. Nigam, Manish K. Pandey,P. Nagesh and Rajeev K. Varshney , Groundnut improvement: use of genetic and genomic tools, 2013. Front. Plant Sci., 25 February 2013 Sec. Plant Genetics and Genomics Volume 4-2013. https://doi.org/10.3389/fpls.2013.00023.
- Nigam SN. 2014. Groundnut at a glance. Pp 121.
Further reading
Groundnut: Plant Information, History, Uses and Nutrition Value
Principles of selecting the best varieties of Groundnut: A Comprehensive Guide
Groundnut Soil requirement, Soil preparation and Planting
Weed Management in Groundnut Farming
Fertilizer requirement for Groundnut Cultivation
Irrigation Requirement and Methods for Groundnut Cultivation
Groundnut Diseases and Management Practices
