Arachis hypogaea L.: A Description
Arachis hypogaea L., commonly known as peanut, is a member of the leguminous family, Fabaceae. It is believed to have originated from South America, specifically in parts of Brazil and Peru. Peanuts have been cultivated for over 3,500 years, and today they are grown worldwide in tropical and subtropical regions.
Common Names
Peanuts are known by various common names across the world. In North America, they are commonly referred to as peanuts or groundnuts, while in the United Kingdom and other parts of Europe, they are known as monkey nuts. In Africa, they are known as goober nuts or pindar, while in Asia and India, they are referred to as groundnuts or Chikki.
Uses
Peanuts are a highly valued crop, not only for their food value but also for their economic importance. They can be eaten raw, boiled, roasted, or fried and are a popular ingredient in many foods such as peanut butter, candy, and confectionery. The oil extracted from peanuts is used as cooking oil and in the manufacture of margarine and soap. The by-products such as peanut meal and peanut skins are used in the animal feed industry.
General Appearance
Peanut plants are low-growing, reaching a height of up to 50cm. The leaves of the plant are composed of four leaflets, while the flowers are yellow and pea-like, with a small size of about 2cm in diameter. The fruit of the plant is a pod, which contains 1 to 4 seeds. The pods develop underground, making peanuts unique among other crops. The seeds are smooth or wrinkled and come in different colors ranging from white, yellow, red, and brown.
Overall, the Arachis hypogaea L. is an important and versatile agricultural crop with numerous uses and a long history of cultivation.
Light Requirements
Arachis hypogaea L. is a crop plant that requires full sunlight exposure to grow efficiently. Therefore, it is recommended to plant them in places that receive a minimum of 6 to 8 hours of direct sunlight every day.
Temperature Requirements
Arachis hypogaea L. thrives well in warm and humid climates. The optimum temperature range for its growth and development falls between 25°C to 30°C. At temperatures above 35°C, the seedlings may experience heat stress, which can affect crop establishment and yield. Additionally, this plant has low tolerance for frost or freezing temperatures as it can lead to stunted growth, yellowing leaves, and wilting.
Soil Requirements
The ideal soil for Arachis hypogaea L. is well-draining, deep, and loose with a pH range of 6.0 to 7.5. The soil's texture should have a good combination of clay, silt, and sand, with a high percentage of organic matter. The crop prefers sandy loam soils to heavy clayey soils. Additionally, the soil should be rich in nutrients such as phosphorous, potassium, and nitrogen, and have adequate levels of calcium, magnesium, sulfur, and micronutrients. It is highly recommended to avoid waterlogged or poorly drained soil, as it can lead to root rot and stunted growth.
Cultivation methods
Arachis hypogaea L., commonly known as peanut or groundnut, is a legume crop that is grown primarily for its edible seeds. It is a warm-season crop that requires a growing period of around 120-150 days depending on the variety and the climatic conditions. The crop is usually grown in sandy loam soils that are well-drained and have a pH range of 5.5-7.0. While the crop can grow in a variety of soil types, it is best to avoid acidic and heavy soils.
The ideal temperature for cultivating peanuts ranges from 25-30°C during the day and 18-25°C at night. The crop can be grown either as a rain-fed crop or an irrigated crop, depending on the availability of water in the region. In areas with low rainfall, the crop can also be grown as a rabi crop by sowing in October-November and harvesting in February-March.
Watering needs
Peanuts require frequent and adequate watering during the growing season to ensure optimal yields. While the crop is relatively drought-tolerant, it requires around 50-75 mm of rainfall per month during the growing season. If rainfall is not sufficient, the crop should be irrigated regularly to prevent moisture stress.
The frequency and amount of irrigation required will depend on the stage of growth, soil moisture levels, and weather conditions. However, it is recommended to avoid overwatering as it can lead to waterlogging, nutrient leaching, and disease incidence.
Fertilization
Fertilization is crucial for achieving high yields and quality peanuts. The crop requires a balanced supply of nutrients, including nitrogen (N), phosphorus (P), and potassium (K), as well as micronutrients such as zinc (Zn) and boron (B).
The recommended fertilization practices for peanut cultivation involve applying 20-30 kg/ha of N, 40-60 kg/ha of P2O5, and 20-30 kg/ha of K2O at sowing time. An additional 20-30 kg/ha of N can be applied at 45-60 days after sowing. The application of micronutrients should be based on soil test results and the specific requirements of the crop.
Pruning
Pruning is not a common practice in peanut cultivation as the crop has a bushy growth habit and does not require support. However, the removal of excess branches and leaves can help improve aeration and light penetration to the lower parts of the plant, especially in dense stands.
If disease or pest incidence is observed in the crop, the affected branches or leaves should be removed promptly to prevent the spread of infection. However, it is crucial to avoid excessive pruning as it can adversely affect the yield and quality of the peanuts.
Propagation methods of Arachis hypogaea L.
Arachis hypogaea L., popularly known as peanut, is an annual legume crop that can be propagated by both sexual and asexual methods.
Sexual propagation
The sexual method of propagation involves the use of seeds. Peanut seeds are matured pods that contain one to four seeds each. The seeds are extracted from the pods, dried to reduce moisture content, and stored until planting.
Before planting, the seeds must be treated by soaking them in water for 10 to 12 hours. After soaking, they are sown in beds or seedling trays at a depth of 5cm. The seedlings sprout within 7 to 10 days after planting. About 50 to 60 days after planting, the seedlings are transplanted to the field with a spacing of 30cm x 10cm between rows and plants, respectively.
Asexual propagation
The asexual method of propagation involves the use of vegetative parts of the plant, such as stem cuttings. This method is mostly used for cultivating desirable cultivars of peanut.
To propagate by stem cuttings, select a healthy plant and cut a stem tip from it. The stem should be about 20cm long and should contain a few leaves. Remove the bottom leaves and dip the stem in rooting hormone. The cutting can be planted in a rooting medium such as sand, peat moss, or vermiculite. Ensure that the cutting is kept moist until roots develop within 2 to 4 weeks.
The rooted cutting can then be transplanted to the field. Peanut plants grown from cuttings are genetically identical to the parent plant and, therefore, retain the desirable traits of the parent cultivar.
Both sexual and asexual methods of propagation are used in the cultivation of peanut. However, sexual propagation is more commonly used for commercial production due to its ease and cost-effectiveness.
Disease Management of Arachis hypogaea L.
The plant Arachis hypogaea L., commonly known as peanut, is susceptible to a number of fungal and bacterial diseases. Some of the most common diseases that affect peanuts include:
- Leaf spots: Leaf spots are caused by various fungi, including Cercospora arachidicola, which causes early leaf spot, and Cercosporidium personatum, which causes late leaf spot. Leaf spots can lead to defoliation, reduced yield, and poor quality nuts.
- Pod rot: Pod rot is caused by the fungus Rhizoctonia solani and can lead to significant yield losses. It typically affects peanuts that are grown in wet conditions and can spread quickly through a field.
- Tomato spotted wilt virus: This virus is transmitted by thrips and can cause stunting, wilting, and necrosis of leaves and stems. Infected plants may also produce fewer and smaller pods.
- Sclerotinia blight: Sclerotinia blight is caused by the fungus Sclerotinia minor and can cause significant yield losses. Symptoms include water-soaked lesions on stems, leaves, and pods, which can lead to the rotting of the peanut plant.
To manage these diseases, growers should practice good sanitation, rotate crops, plant pathogen-free seed, and use fungicides when appropriate. Fungicides that are commonly used to manage peanut diseases include azoxystrobin, chlorothalonil, and propiconazole.
Pest Management of Arachis hypogaea L.
Peanuts are also susceptible to a number of insect pests that can cause significant damage to the crop. Some of the most common peanut pests include:
- Leafhoppers: Leafhoppers can cause significant damage to peanuts by feeding on the leaves and transmitting plant viruses such as tomato spotted wilt virus. Infested plants may exhibit stunted growth, yellowing, and reduced yield.
- Thrips: Thrips can cause significant damage to peanuts by feeding on the leaves and transmitting tomato spotted wilt virus. Infested plants may exhibit stunted growth, necrosis, and reduced yield.
- Corn earworms: Corn earworms are a major pest of peanuts, with larvae feeding on the pods and damaging the developing nuts. Infested plants may exhibit reduced yield and poor quality nuts.
- Spider mites: Spider mites can cause damage to peanuts by feeding on the leaves and causing chlorosis, necrosis, and reduced yield. Infested plants may also produce smaller and lower-quality nuts.
To manage these pests, growers should use integrated pest management practices, including the use of crop monitoring, cultural practices, biological control, and chemical control. Insecticides that are commonly used to manage peanut pests include carbaryl, malathion, and spinosad. It is important to follow all label directions when using insecticides and to avoid spraying during bloom to avoid damaging pollinators.
