Arachis hypogaea L.: Overview
Arachis hypogaea L., commonly known as peanut or groundnut, is a legume plant native to South America. It is a valuable crop widely cultivated in many parts of the world, particularly in Asia, Africa, and the Americas.
Appearance
Arachis hypogaea is a small annual plant that grows up to 30-50 cm tall. The plant has deep roots that can reach up to 1.5 meters in depth. The leaves are trifoliate and ovate, with a length of 1-7 cm and a width of 1-6 cm. The flowers are yellow, and the fruits grow in clusters underground.
Common Names
Arachis hypogaea is commonly known as peanut or groundnut. Other names include earthnut, goober, monkey nut, and pygmy nut.
Uses
Arachis hypogaea is a valuable crop with numerous uses in food, medicine, and industry. The nuts are edible and are a rich source of protein, oil, vitamins, and minerals. They are used in various dishes, such as peanut butter, snacks, and confectionery. The plant also serves as a feed for livestock and poultry.
In medicine, peanuts have been used to treat various health conditions, such as diabetes, digestive disorders, and skin diseases. The oil extracted from the nuts is used in cosmetics and for making soap and lubricants. Additionally, the plant residue and shells are used as fuel and in the production of paper and plastic.
Light Requirements
Arachis hypogaea L. is a light-loving plant that requires full sun to produce maximum yield. The plant should receive 6-8 hours of direct sunlight to thrive.
Temperature Requirements
The plant grows well in warm, tropical and subtropical regions with temperatures ranging between 20 to 35°C. However, it cannot tolerate frost and requires a frost-free period of at least 4-5 months.
Soil Requirements
The plant grows best in well-draining loamy soils that are rich in organic matter. The soil pH should range between 5.8-6.2 to facilitate maximum nutrient uptake. The ideal soil depth for cultivation is between 30-50 cm, which allows for good root growth and development. Furthermore, the plant requires adequate soil moisture, and drought stress should be avoided during the growing season.
Cultivation Methods
The cultivation of Arachis hypogaea (peanuts) requires well-drained, sandy loam soils with a pH range of 5.9-7.0. The planting season varies per region, but it is advised to plant after the last frost of the season. Spacing between rows should be between 60-90 cm, and between plants 15-20 cm. Peanuts grow best under full sunlight and warm temperatures ranging between 21-32°C.
Watering Needs
Peanuts require uniform moisture throughout their growing period, but over-watering must be avoided. It is recommended to water as soon as the topsoil starts to dry, and during drought periods. Irrigation by sprinklers, furrows, or drip systems is ideal for peanut growth.
Fertilization
Peanuts require well-formulated fertilizer with a balanced ratio of nitrogen (N), phosphorus (P), and potassium (K) for optimal growth. It is recommended to use phosphorus-rich fertilizer in the early stages, followed by nitrogen-rich during pod formation and potassium-rich during flowering. Applying organic material such as compost improves soil structure, fertility, and retains moisture.
Pruning
Pruning is not a common practice in cultivating peanuts. However, removing dead flowers and manipulating branches to create a well-spaced canopy, combined with periodic removal of weeds, improves the quality of the harvest. Proper canopy management improves airflow, reduces the risk of diseases and pests, and provides better sunlight exposure to growing pods.
Propagation of Arachis hypogaea L.
The plant Arachis hypogaea L., commonly known as peanut or groundnut, can be propagated through various methods. The selection of propagation method depends on the availability of resources and desired results.
Seed propagation
Seed propagation is the most common method used for propagating Arachis hypogaea L. The peanut seeds germinate within 7-10 days when sown at a depth of 3-5 cm in well-drained and fertile soil. The ideal temperature for germination is between 20-25°C, and the pH of the soil should be between 5.5-7.5.
Cuttings propagation
Cuttings propagation is another method that can be used to propagate Arachis hypogaea L. It involves taking cuttings from a mature plant and rooting them in a suitable medium. The cuttings are taken when the plant is in its vegetative phase, and the nodes should be dipped in rooting hormone before planting. The cuttings should be planted in a well-drained and fertile soil, preferably in a warm and humid environment. The roots usually appear within 3-4 weeks, and the new plant can be transplanted into the field after 4-6 weeks.
Layering propagation
Layering propagation is a simple method that involves bending a branch of a mature plant and burying it in the soil. The buried portion should be kept moist, and roots will emerge from the buried stem. The rooted stem can be separated from the mother plant and transplanted into the field. This method is usually used to propagate varieties that have low seed germination rates.
Grafting propagation
Grafting propagation is a method in which a desirable cultivar is grafted onto a rootstock of a vigorous plant. This method is used to propagate high-yielding varieties that have poor stress tolerance. In this method, the scion should be collected from a disease-free plant, and it should be grafted onto a compatible rootstock. The graft should be protected from high temperature and low humidity until it establishes.
Arachis hypogaea L.: Disease Management
Arachis hypogaea L., commonly known as peanut or groundnut, is susceptible to many fungal, bacterial, and viral diseases. Fungal diseases appear to be the most frequent and problematic ones for peanut production. These diseases affect the leaves, stems, pods, and seed quality of the peanut plant, leading to yield loss, and reducing the quality of nuts.
Seed treatments with fungicides before planting or in-furrow application of fungicides at planting time are the most effective ways to manage soil-borne diseases such as Rhizoctonia limb rot, Pythium pod rot, and Fusarium wilt. Cultural practices such as crop rotation, drainage, and maintaining proper soil pH levels may also help in preventing these diseases.
For foliar diseases such as early and late leaf spot disease, managing plant PDS (post-deposition sprays) of fungicidal sprays is effective. Integrated approaches that combine resistant cultivars, cultural practices, and chemical control provide the best management option for many fungal diseases.
Bacterial diseases such as bacterial wilt, stem rot, and leaf spots can be managed using disease-free planting materials. Resistant varieties and maintaining plant hygiene practices may also help. However, the application of copper-based bactericides provides a limited and temporary effect.
Virus diseases such as peanut mottle virus, peanut stunt virus, and tomato spotted wilt virus can transmit through the feeding of thrips and aphids. The use of virus-free seed, weed control measures, and the control of the thrips population with insecticides can reduce the incidence of virus diseases. Plant residues carry viruses; therefore, effective residue management is crucial for disease control.
Arachis hypogaea L.: Pest Management
Arachis hypogaea L. is vulnerable to many insect pests during its growth cycle. These pests can cause direct damage or transmit viral or fungal diseases to the plant. The most common insect pests of groundnuts are thrips, aphids, caterpillars, leafhoppers, whiteflies, and pod borers.
Integrated pest management techniques are the most effective ways to manage insects in groundnuts. Cultural practices such as crop rotation can disrupt the insect growth cycle. Early detection and eradication of insect pests are crucial in preventing their populations from increasing.
Biological pest control methods utilize insect predators, parasitoids, and pathogens to control insect pests. The use of biological agents such as nematodes, fungi, and bacteria may also be effective in managing soil-borne pests. Chemical control measures should use insecticides with low toxicity to non-target areas.
The use of resistant peanut cultivars is also an essential tool in managing insect pests in groundnuts. Resistant varieties can reduce the susceptibility of plants to specific insect pests, leading to less reliance on pesticides.
Insect traps, pheromone traps, and mass trapping techniques are other pest management practices that can help in controlling insect populations. The use of traps can reduce chemical use and serve as an early warning system for pest infestations.
