Groundnut physiological maturity
Uproot one plant and closely observe:
- Yellowing and shedding of leaves
- Inside of the pods are brownish when opened
- Seed coat is thin with papery texture
- Seed coat in mature kernel is not easily rubbed off by hand
- Moisture content of the shells is between 36-50% depending on variety
- Premature harvesting is not recommended, as pods will be difficult to dry, they yield less oil, & there is low seed viability and short shelf life.
- Losses can be up to 30% if harvesting is delayed.
- If the soil condition is moist, the pods can sprout.
- Harvesting needs extra care, knowledge and skills.
- Hand Lifting -Appropriate for sandy loam soils that are well drained and loose. Not suit-able for groundnut spreading varieties as large pods remain in the soils.
- Hand hoe – Suitable for erect groundnut varieties. Soil should be sufficiently moist for easy harvesting without leaving pods in the soil.
- Modified ox-plough – Depth of cut adjusted to 15cm in the ground, below the groundnut pods to ensure effective loosening and lifting of the pods. The loosened groundnuts are immediately hand lifted.
- Groundnut lifter– Conventional ox-plough is modified by fitting a groundnut lifting attachment.
Curing and drying groundnuts
- Groundnut should be allowed to wilt for a day to reduce moisture.
- Curing reduces chances of rotting and moulding, preserves oil quantity and quality in the kernels, reduces crop moisture and bulkiness.
- Traditional methods
Pods spread at bare ground to dry with pods facing downwards.
Rapid drying under hot sun may cause the pods and kernels to become brittle and liable to cracking.
- A Frame
After wilting groundnuts are stalked in an A-frame made from poles. Lower rail should be 30cm from the ground level. The pods should be placed facing the inside part of the A-frame for protection against the direct sun and rain.
- Tripod or Quadruped Frame
Made by using 3 or 4 poles tied together at a single point at the top with rails tied at alternating levels from the bottom to the top of the sides of the frame. Wilted crop packed with pods facing inwards Hand plucking- Manually plucking which allows separation of healthy and mature pods from shrivelled and diseased ones is labour intensive.
Make use of a manual or electric groundnut sheller for removing shells
- It is the stage of crop production immediately following harvest, including cooling, cleaning, sorting and packing.
- The moment a crop is removed from the ground, or separated from its parent plant, it begins to deteriorate which affects more its quality than its quantity and can in the long-term result in a definite loss.
- Post-harvest losses are significantly high during harvesting depending on the soil moisture conditions.
- If soil is too dry or produce harvested late, pods can strip at lifting pods susceptible to attack by fungi.
Fungal toxins also called mycotoxins are major constraint to increased productivity and market competitiveness (Myco-fungus. Toxins = poisons). Most common fungal toxins are aflatoxin which are produced by Aspergillus flavus and A. parasiticus.
Grains especially groundnut are susceptible to contamination through poor production, harvest-ing, processing and storage.
EFFECTS OF AFLATOXIN
Aflatoxins are not destroyed by cooking. Cooking or processing grain e.g. peanut butter making does not remove aflatoxin. Livestock must not be fed mouldy grain as they become sick and their meat, milk, eggs become contaminated.
Two main effects of aflatoxins:
- Eating contaminated food results in aflatoxicosis.
- Chronic exposure: leads to liver damage, immune suppression, malnutrition and stunted growth in children
- High-level ingestion (Acute exposure) can lead to death.
- Aflatoxins may reduce the mar-ket value of peanuts and in serious cases they can be rejected. from the market.