Why venture into groundnuts farming?
The seeds are rich in oil 38-50%, protein 25%, calcium, magnesium, phosphorus, potassium and vitamins.
They are reported to have medicinal value particularly in the treatment of diarrhea and haemophilia.
- Groundnuts are processed into oil used for cooking.
- Groundnuts boost fertility
- Help fight depression
- Boost the human memory power
- Important in blood sugar control
- Cancer prevention
- Prevents gallstones
- Very low in cholesterol
- Lowers heart problems
- Reduces the risk of weight gain
The cake that comes out of oil press is ground into flour and used in many human foods as its rich in protein.
The seeds are eaten raw, as roasted snack, used in confectionary, used in soups and made into sauces to accompany meat and starchy dishes.
Small scale farmers grow it both for cash and subsistence.
Climate water and soil requirements
- The crop grows well in warm tropics and subtropics below 1500 M above sea level.
- Optimum daily growing temperatures requirements are 30º C and growth stops at 15º C.
- The plant does not tolerate frost and cooler temperatures delay flowering and seed formation.
- Water requirements are 500 to 600 mm well distributed throughout the growing season for good growth.
- The crop is drought resistant and can survive severe lack of water but yields are reduced.
Pods grow underground crumbly free draining soils are required. But the plants also grow well in heavier clay soils.
- Harvesting in wet condition should be avoided, to prevent development of aflatoxin, a severe poison produced by Aspergillus spp of fungus, which releases chemicals dangerous to human health. The fungus causes both seeds and seedlings to rot. The infected seedlings are covered with black fungal spores. PH requirements range from 5.5 to 6.5.
To control seedling blights caused by soil bacteria and fungi, and also other fungal diseases, a fungicide treatment is recommended. Thiram gives good protection and can be applied as a dust at 120 g of thiram/100 kg of seed. The dust must be uniformly mixed with the seed.
All soils, other than very heavy, are suitable for growing groundnut, but the best are deep, well drained sandy, sandy loam soils. The latter facilitate the forcing of the developing fruit into the soil (pegging). Groundnut will not grow well or fix nitrogen in acidic or infertile soils. The soils should have a pH between 5.3 and 7.3. Groundnut plants are sensitive to salinity, and high soil acidity (pH<5) could induce magnesium or aluminium toxicity. In this type of soil, calcium should be added to maintain the pH above 6.
Time of planting
The planting date is difficult to standardize. However, farmers should plant as soon as there is adequate moisture in the ground to ensure good germination. In general, groundnuts are planted between February and April during the first season and in early August for the second season. Planting in the first two weeks after the onset of rains is considered suitable. Planting early in the season helps to improve yields and seed quality, and reduce the incidence of rosette disease. Long duration varieties should only be planted with the first rains in the first season. Short duration varieties can be planted in either season.
Plough the land and harrow to a good tilth. Prepare ridges which are 80cm apart with flattish tops.
Planting date is linked to rainfall distribution in the area and length of the crop season. Soil moisture must be sufficient to guarantee good germination. Seeds must not be sown immediately after heavy rains since they imbibe too much water, which causes rotting. This also results in excessive soil compaction, which may hinder germination. In general early sowing improves yields (significant delay in sowing can reduce yield by 50%) and seed quality
Seeds should be sown at a depth of 5–6 cm. To ensure uniform sowing depth, germination and crop stand, it is suggested that a groove 5–6 cm in depth is made along the rows for planting and, once the seed has been planted at the right depth and spacing, the soil is pressed down to ensure good contact with the seeds, enabling them to extract moisture more effectively. It is important to sow groundnut seed in rows and at the right spacing as this helps to reduce the incidence of rosette disease, ensures a more uniform pod maturity, better quality seed and maximizes yield. Planting groundnut plants closer together results in individual plants setting fewer pods, but over a short period of time. Overall, this will ensure that the pods will be of a similar age and stage of development and, therefore, make it easier to decide when to harvest. Wider spacing will produce fewer yields per hectare.
Spacing depends on the growth habit and the variety. Small seeded Spanish types (bunch) are spaced at 30-45 cm between rows and 7.5-10 cm between plants. This gives an optimum plant population of 167,000 per hectare. The large-seeded Virginia types (runner) are spaced at 60 cm between rows and 10-15 cm between stations, giving an optimum plant population of 89,000 per hectare. Under irrigation, plant population can be as high as 250,000 plants/ha. This depends on variety characteristics, seed quality and planting density. With manual sowing, individual seeds are sown 3-5 cm deep.
A reasonable level of organic matter must be maintained in the light, weakly structured, tropical soils where groundnuts are grown. Groundnut requires adequate levels of phosphorus, potassium, magnesium and particularly calcium, which are required for maximizing yield and good quality seed. For farmers who can afford artificial fertilizers, application of Single Super Phosphate (SSP) at the rate of 100–125 kg/ha or Triple Super Phosphate (TSP) at 80–90 kg/ha will boost yield. SSP or TSP should be worked into the soil before planting. In areas where there is a high incidence of empty pods (‘pops’), there could well be a shortage of calcium in the soil. To rectify this, depending on the soil type and seed variety a treatment of Gypsum at the rate of 200–400 kg/ha (up to 500–1000 kg/ha if the soil is particularly poor) at early flowering will reduce the incidence of empty pods. This requires soil analysis.
The groundnut fits into a wide range of farming systems. It can follow both cereals (maize, pearl millet and sorghum) and
root crops (cassava and sweet potatoes). Groundnut does well on virgin land or immediately following a grass fallow or a well fertilized crop such as maize.
To avoid the build-up of pests and diseases, groundnut should not be grown continuously on the same land.
A rotation of 3 years or longer can usually reduce disease, pest and weed problems. Because of the incidence of pests and soil-borne diseases, groundnut should not be grown after cotton, although cotton can be used in rotation after groundnut.
Other legumes, tobacco, tomatoes and certain other vegetables may cause a build-up of nematodes and soil-borne diseases and, therefore, should be avoided in rotation with groundnuts. Cereals, such as maize, sorghum and millet are good rotational crops.
Avoid groundnut-groundnut rotation to discourage the build-up of pest and diseases
Although a number of crops are used as intercrops with groundnut, results from intercropping research have been inconsistent, so any advantages or disadvantages are not known.
Groundnut cannot compete effectively with weeds, particularly 3–6 weeks after sowing; therefore, early removal of weeds is important. Generally, 2 weedings are recommended, the first before flowering and at least another during pegging. If early weeding is done well, and crop spacing recommendations followed, then the weeds that come up later are smothered with the vigorous growth of the crop. If necessary pay extra attention when walking through a flowering groundnut field in order not to disturb the flowering plants.
Weeding by hand
When weeding, it is very important to avoid covering the developed plant with earth (including earthing up) as this can increase diseases (e.g. white mould), reduce flowering and pod development and, therefore, reduce pod yield. Once flowering and pegging begins it is advisable to weed by hand pulling, rather than by using a hoe, as this is less likely to disturb any developing pods.
Pre- and post-emergence herbicides may be used to eradicate weeds but they are very expensive for most small-scale farmers. Follow the manufacturers’ instructions with regard to dosage.
Seeds for sowing should be stored in their pods to be shelled a few days before planting.
Always select healthy looking nuts as planting material. Some farmers hold that smaller seeds germinate faster than larger seeds which take longer before they are completely hydrated for germination. They should also be clean and well filled but not wrinkled
Sowing seeds to a depth of 5-8 cm at a seed rate of 40-50 kg per ha is recommended depending on seed size.
Germination is dependent on the moisture availability, air circulation, soil structure and light.
Groundnuts have two main types namely:-
- Bunch type e.g. Red Valentia maturing within 90 – 100 days
- Runner type e.g. Homa Bay maturing in 120-150days
Varieties and Yields
The present growers yield in Kenya is 450-700kg/ha can be doubled through Improvement of husbandry practices.
Red Valencia 1500, manipinta 2450, Makulu Red 2750, Bukene 1530, Asyria Mwitunde 1300, Texas peanut 1360, Severe 116 ( white) 1250, Atika 900, Homa Bay 770
Groundnuts compete poorly with weeds particularly during the early stages of growth. Earthing up should be done at the time of weeding to encourage pegging (the penetration of young nuts into the soil). Hand weeding is recommended after initiation of pegging to prevent disturbance to the growing nuts or damaging the flowers. Clean weeding should take place up to 6 weeks after which only hand weeding should be done.
Calcium is critically required during the pod formation stage and lack of it results in empty pods. Generally nitrogen fertilizers are not required as the plant is leguminous and fixes Nitrogen. In acidic soils lime can be applied to raise the pH and supply calcium.
Moisture stress at flowering or pod formation stages reduces yields and therefore supplementary irrigation may be required for increased production and high quality seed.
Rock phosphate at the rate of 200kg/ha is recommended in heavily eroded soils.
Maturity period is 90-130 days depending on the variety. Seeds meant for planting the following year should not be shelled until a few days before planting.
The major pests and disease challenging groundnut growing are shown below:-
- Damping off disease
- Rotting of stems Seedling, petioles Certified seed, crop rotation
- Leaf spot leaves Brown ring spots Shedding leaves Crop rotation, field hygiene
- Rust All aerial parts except flowers Leaves, stems Remove volunteer groundnut plants, crop rotation
- Aspergillus crown rot All growth stages Wilting of the plant Rapid drying of nuts to 10% M.C
- Bacterial wilt All stages Plant wilting Rotation with cereals
- Groundnut rosette Virus All growth stages Yellowing, mottling, stunting Early planting, control of vector-Aphids
Groundnut Diseases and their Control
Groundnut production is adversely affected by a large number of fungal, viral and bacterial diseases. Most of these are widespread, but only a few of them are economically significant. The major diseases include groundnut rosette, ELS, LLS, rust and aflatoxin contamination.
Groundnut Rosette Disease
Groundnut rosette disease, a viral disease transmitted by aphids, is the most common and most significant disease of groundnut in all regions where this crop is grown. It has been a major factor in the decline of the groundnut yields.
The disease can manifest two types of symptom: green or yellow (chlorotic). The affected plants are stunted and present a bushy appearance with a marked reduction in leaflet size with visible mottling.
• Yellow (chlorotic) rosette causes plants to initially develop a faint mottling on young leaves.
Subsequently, leaflets are yellow with green veins. Plants infected when young produce progressively smaller, distorted, curled and yellow leaflets, while the symptoms in older plants are generally restricted to a few branches or the apical portion of the plant.
• Green rosette disease shows middle mottling on young leaflets with some leaf curling, but leaves are not distorted. Plants infected when young are severely stunted and dark green in color. Total yield losses have been reported in susceptible varieties. Early infected plants produce no yield and there is no control once a plant is infected.
A 100% loss in pod yield due to either chlorotic or green rosette disease may result if infection occurs before flowering. Control of aphids will prevent further spread of the disease.
Management 1. Chemical control:
• Spray the entire plant with insecticides, 14 days after emergence (usually 5 ml per 2 l of water, but check the label for instructions) and then at 14-day intervals with a total of three sprayings.
Management 2. Cropping practices:
• Planting should be done as soon as there is enough moisture in the soil
• Close planting should be adopted
Closely planted groundnuts providing a good covering of the soil against water loss
• Intercropping with cereals (maize, millet or sorghum) has been found to be effective in reducing the disease incidence
Groundnuts inter-cropped with sugarcane
Note: Early sowing and close spacing of rows reduce disease incidence
Management 3. Host plant resistance:
• Rosette-resistant varieties should be used for planting. Resistant varieties.
Management4. Cultural control
• Crop rotation with crops like maize has been shown to provide partial management of leaf spots
• Early sowing has been shown to reduce the severity of leaf spot diseases. The date of sowing should be adjusted to avoid conditions favorable for rapid disease development.
• Burying all groundnut crop residues by deep plowing will reduce initial inoculum. Chemical control
• Multiple applications of a fungicide such as benomyl, captafol, chlorothalonil, copper hydroxide, mancozeb or sulfur fungicides may control ELS and LLS. However, carbendazim (0.05%) has been found to control both leaf spots very effectively.
• Three sprayings of 0.2% chlorothalonil at intervals of 10-15 days starting at 40 days after germination up to 90 days provides effective control to ELS and LLSs. Use of resistant lines • Grow cultivars tolerant to LLS: Sources of resistance to both ELS and LLSs have been identified in groundnut and used to develop varieties with resistance. Recently released groundnut varieties in Nigeria are tolerant to foliar diseases.
B. Leaf spot
There are two main forms of the leaf spot fungal disease – early and late. Early leaf spot may occur as early as 2 weeks after
crop emergence. Lesions produced by this fungus are roughly circular, dark brown on the upper surface with chlorotic (yellow) halos surrounding the darker lesions and a lighter shade of brown on the lower surface of the leaflets. Severe attacks can cause heavy defoliation and result in a large yield loss.
Late leaf spot occurs later in the season and has nearly circular lesions which are darker than those of early leaf spot. Late leaf spot does not normally affect yield reduction as severely as early leaf spot. On the lower leaf surface where most of the sporulation occurs, the lesions are black.
Since the leaf spot pathogens survive mainly in crop debris, cultural practices such as crop rotation, burying crop debris during land preparation and early sowing can significantly reduce the incidence of the diseases.
Chemical control may not be economical for rainfed crops but the fungicides ridomil, milraz or mancozeb (Dithane M-45®) can be used at the rate of 50 g of the chemical with 20 l water. Apply when lesions are first seen and then at 14- day intervals for 3–4 sprays.
C. Groundnut Rusts Rust (Puccinia arachidis Speg.)
This is one of the important foliar diseases that reduces seed quality and causes substantial losses to groundnut production worldwide.
Management Cultural Control
• Crop rotation and field sanitation. This helps to reduce the initial inoculum in the soil
• Strict plant quarantine regulations should be enforced to avoid the spread of rust on pods or seeds to disease-free areas
• Early sowing minimizes incidence of the disease
• Intercropping cereal (maize, pearl millet or sorghum) with groundnut has been found useful in reducing the intensity of rust.
Destroy volunteer (self-sown) groundnut plants and crop debris to reduce/ limit primary source of inoculum.
There are some chemicals effective for the control of rust disease, and these should be applied as soon as the symptoms are noticed. Some of the chemicals used are Chlorothaalonil 0.2%, Mancozeb 0.25% and Hexaconazole/ propaconazole. Use of resistant varieties. In places where rust disease is endemic (common), the use of resistant/ tolerant varieties in combination with a little chemical control provides the best results.
Rust occurrence is generally sporadic but sometimes there are severe outbreaks. It can survive in volunteer plants and spores can disperse over long distances to infect other areas. Rust is characterized by orange-red pustules on the leaves which later turn dark brown and cause curling of leaflets and defoliation.
Aflatoxins are a group of toxic metabolites produced by the fungi Aspergillus flavus and Aspergillus parasiticus. Aflatoxins are some of the most potent toxic substances found in foods and feeds.
Scientific research shows that aflatoxin can cause various types of cancer in both animal species and humans. It has been reported to cause severe illness and death in many parts of the world.
Chronic intake of aflatoxin in animals can lead to poor food intake and weight loss. Aflatoxin contamination can occur in the field, during postharvest drying and storage, and even during transportation. Crop husbandry practices, mechanical damage, insect and bird damage, climatic conditions (drought, stress or excessive rainfall), and soil factors, in addition to host-plant susceptibility, significantly influence aflatoxin contamination.
Recommended postharvest practices to manage aflatoxin infection:
• Do not delay harvest when groundnuts have reached maturity
• Immediately after harvesting, pluck the pods off the haulms and place to dry as soon as possible
• Harvest carefully to avoid mechanical damage. This is particularly important if hand hoes are used to harvest the pods. • Avoid field drying of groundnuts when attached to haulms as aflatoxins increase with delays of produce in the field.
• Do not dry produce in contact with soil. Use clean sheets, for example polythene sheets or tarpaulin or mats made of papyrus, cemented grounds or raised structures
• Dry harvested pods to moisture content level below 13%
• Avoid mixing diseased or infected pods with healthy ones.
• Separate out immature pods as well as those infested with pests and diseases during shelling
• Do not shell by beating or trampling on groundnut in shells. Manual or motorized shelling is recommended but care should be taken that the shellers do not damage the pods. Use hand or motorized shellers specifically designed for groundnuts
• Do not sprinkle water on dry pods while using mechanical shellers. Instead, adjust (where possible) the space between blades and the sieve according to pod size to reduce breakage
• Remove shriveled, discolored, moldy and damaged grains from the lot including groundnuts with damaged testa and dispose them.
• Remove dust and foreign material which can be a source of contamination.
• Properly dry groundnuts for safe storage to moisture content to less than 10%
• Place them in packages that will maintain suitable environment and prevent or restrict moisture pick-up and insect/rodent infestation
• Use new/clean gunny or polybags to store the groundnuts
• Do not place bags directly on floor
• Do not heap groundnuts in shells/pods on the floor/ground inside storage structure
• Maintain proper storage facilities (well-ventilated, dry and with low relative humidity) and take care not to expose produce to moisture during transport and marketing
• Control insects and rodents during storage
• Do not mix new produce with old stock.
The majority of insect pests that attack groundnut can be grouped as:
soil inhabiting insects (e.g. termites, white grubs, earwigs, subterranean ants);
foliage feeding insects (leaf miner, caterpillars, armyworm, bollworm);
those that transmit viral diseases (thrips, aphids); and
insects that damage flowers and growing parts (blister beetle). Of all these, termites, aphids, thrips and leaf miner are the most important.
It is very important to harvest groundnuts at the correct time. Flowering is indeterminate in the groundnut; therefore there are a variable proportion of mature and immature pods at the end of the crop cycle. Groundnuts are mature when 70-80% of the inside of the pods shells have dark markings and the kernels are plump, with colour characteristic of that variety. If harvested too early, the seeds will shrink when drying which lowers the yield, oil content and quality of the seed. Delays in harvesting will result in poor quality seed due to mould infections and subsequent aflatoxin contamination of the seeds/pods. Late harvesting also reduces yield because higher proportions of pods are left in the ground due to the pegs being weak and the pods breaking off. If harvested late, some non-dormant varieties will begin to sprout in the field resulting in yield losses.
Indicators for harvesting time
Leaf fall is not a good indicator of when to harvest. It is recommended that a few plants (3–5) should be pulled up randomly and the pods removed and shelled. The insides of the shells should be examined. If the majority of pods (70% upwards) have dark markings inside the shell and the seeds are plump and the correct colour for that variety, then the groundnuts are mature and ready for harvest. If the crop is severely defoliated as a result of disease (only one or two leaves per branch) or if sprouting has begun, the crop should be harvested regardless of maturity. The estimated period of maturity for each variety can be used as a rough guide.
Harvesting by hand only is more suitable for the bunch/erect groundnut varieties in sandy, loam soils which are well drained. When the soil is wet and heavy or very dry, it is much more difficult to pull up the whole plant without losing pods.
Hand lifting with a hoe or fork
By using a hoe during harvesting it is possible to lift plants out of heavy or dry soil with a reduced pod loss. Spreading/runners varieties can also be more easily lifted. Care should be taken not to damage the pods with the hoe as damage makes the pods susceptible to fungal attack. A hoe fork lessens the likelihood of such damage.
It is important to shake the plant after lifting to remove excess soil from the pods, particularly when the soil is wet or heavy. Soil stuck to the pods will lengthen drying times and produce better conditions for the development of unwanted fungal growth.
The primary objective of curing or drying is to achieve a rapid but steady drying of pods in order to avoid aflatoxin contamination. Harvested plants should be staked in the field and left there for a few days to allow them to dry in the sun and air, before stripping the pods. The correct drying or curing of the harvested groundnuts is very important as poor curing can help induce fungal growth (producing aflatoxin contamination) and reduce seed quality for consumption, marketing and germination for the following season’s planting.
The moisture content of the pods should be reduced to 6–8%. This can normally be achieved by drying the pods in the sun for 6-7 days, taking care to cover them if it rains.
There are different ways of drying the pods, some of which are better than others. It is particularly important to note that if the pods are exposed to the sun for too long the seed quality can deteriorate considerably and germination can be affected. The different methods of drying are explained below.
- Drying in windrows
- Drying on mats
- Decortication or Shelling
Shelling is usually done by hands. However, hand-operated machines are currently available. Care should be taken to prevent cracking of the kernels. The following steps are important for maximum benefit in groundnut decortication:
• Separate immature pods as well as those infested with pests and diseases
• Do not shell by beating or trampling
• Either manual or motorized shelling can be used, but only if the shellers do not damage the pods
• Remove shriveled, discolored, moldy and damaged grains from the lot including groundnuts with damaged testa and dispose them
• Remove dust, and foreign material which can provide a source of contamination.
This operation consists of separating the pods from the vegetative parts of the plants (vines). In traditional farming systems, manual stripping is the rule. Pods are individually detached from the vines and therefore dry very quickly stabilizing at 6-8% moisture content. The process results in a perfect quality product. This technique is used for the production of edible or confectionery groundnuts in order to minimize pod damage and contamination by Aspergillus flavus. However, stripping is most often done using sticks. These reduce the heap of groundnut plants into a mixture of chopped vines and partially broken pods that are then separated by winnowing.
Groundnuts should be stored under the following conditions:
Collect quality raw material (well filled mature pods), clean, free from visible seeds with no Insect damage, well cured (6-8% moisture content) clean storage facilities; treat storage facilities and seeds; check seeds regularly during storage (according to storage period.)
It is best to store groundnuts in their shell. Good drying of the pods to 7–8% moisture content will help to ensure that the seeds remain in good condition during storage. Never bag groundnuts for storage if the pods are still damp.
Before storing, poor, damaged, shrivelled, rotten, or fungus-infected pods should be removed. Whatever the storage container, it is important to ensure that the store is dry and that there is good ventilation so that the pods/seeds do not increase in moisture content, which would encourage fungal growth. Ideally the store should be cool, as this prolongs the storage life of the pods.
Note. Moisture is the key to safe storage and moisture content of grain is related to relative humidity of surrounding air. Safe moisture content of cereal is 13% – 15%
How to test moisture content in grain
- Use dry bottle with a lid.
- Put one table spoon of salt in the bottle.
- Pour a half glass of groundnut in the bottle
- Seal the lid and shake up to mix well
- Place the bottle in the sunshine for 30 minutes
- If the grain is not dry, then the moisture will be attached to the bottle wall which will therefore need more drying.
Storage Temperature and Hygiene
Very high temperature 66∙ºC will destroy seeds. High temperature 21-24 ºC speed up respiration of grains. The lower the temperature the better. Stores should be kept clean at all time. Grain is dried clean and free from discolored and low quality seed. Bags be kept off floor on wooden platform to avoid absorption of moisture. Produce be treated with pesticide before taken to the store.
Bags should be made of a material which allows the air to circulate, therefore, gunny bags are recommended. Do not use polythene or polypropylene bags as these restrict air flow and fungal growth could occur. For the same reason, do not cover bags with plastic or tarpaulin (canvas) which may also restrict ventilation and increase condensation. Bags should be stored away from the ground on wooden slats to avoid damage from dampness. If bags are stacked, a gap should be left between stacks to allow ventilation. Do not stack bags more than ten bags high.
Contact treatments for unshelled groundnuts
Stacking sites should be treated with insecticide dust before windrows and stacks are formed for drying the groundnuts. The surrounding should also be treated to protect the site. Groundnuts are thus protected against termites. Storage areas, containers, drums, bags and storage equipment (conveyors, etc.) should be treated before storing groundnuts. Cleaning of these areas can be followed by fumigation or spraying with insecticides.
Pesticides are applied using a sandwich technique. Seeds are dusted during bagging, and then an insecticide dust is applied between each layer of bags. Organophosphates are contact insecticides currently used. Other available products with long residual activity include Ethyl-Pyrimiphos (Actellic) Methylchlorpyriphos (Reldan). Their residual activity is low in the open air but is effective for more than 6 months.
Groundnut seeds (sorted pods or kernels) can be treated under airtight plastic, sealed silos or warehouses. Bags are arranged to form a pyramid. The base is sealed with a row of sandbags. Hydrogen phosphide (PH3) is the only authorized fumigant. It is available in tablet form and its use requires absolute adherence to manufacture’s recommendations in order for it to be effective.
Successful fumigation depends on ambient moisture, fumigant dose and duration. Fumigant dose can be reduced in airtight treatment areas with high temperature. Stored groundnuts should be regularly checked and a seed sample taken every 3 weeks to ensure proper conservation.
Physical and mechanical methods
These methods are low cost, effective and readily available to farmers. Several techniques are used, depending on the area:
Groundnuts are mixed with powdered minerals (ashes, sand, etc.) that act as
• abrasives or physical barriers; sealed containers(silos) in which anoxic conditions limit insect development, Temperatures below (<5°C) or above (>40°C) are optimum for insect development.
Are smaller than insects and appears as dusts on grain. Some feed on grains which others feed on moulds developing on grains. Mites are associated with high moisture content in stored seeds / grains.
Some of the insects that damage the grain begin their attack in the field several weeks before harvest. E.g. pulse beetle. Survival of storage insects depend on temperature and moisture content (temperature >42 degrees ºC or < 10 degrees ºC will kill insects and moisture content below 8% will not permit insects multiplication). Damage by one insect may lead to further damage by second type of insects e.g. grain weevil destroys sound grain, its lava bores into grain and feeds on endosperm. Red flour beetle, which feeds on the grain dust, further attacks damaged grain. Saw beetle also feed on the damaged grain.
Rats and mice are most important rodents of the stored food. They cause damage by:
Contaminating with the grains with excretion
Causing Critical microbiological problems in groundnut
Groundnuts Quality and marketing
The quality of groundnut is determined very much at the farm level. Good management practices like planting, weeding, harvesting, drying and storage on-farm (as set out in this manual) will ensure that the pods/seeds are marketable. A buyer will, in particular, be looking for: varietal purity (at least 95%), low moisture content (7–8%), high shelling percentage (above 55%), low level of damaged pods/ kernels (less than 17%) and no aflatoxin contamination. These are normaly ideals shown on the packaging material.
General characteristics that determine quality of groundnuts
Variety: Sorting should be done according to the same variety of the groundnut for uniformity in colours, size and variety.
Critical microbiological problem in groundnut / Quality and marketing
Premature or discolored or spoiled grains: This gives or lowers the quality and gives a poor presentation.
Broken or fragmented grains: This allows the mould to use exposed material and facilitates easy spread. The mould produces aflatoxin, which is a worldwide problem because, is remains in the food even after the fungus that produces it has died.
Moisture content: Should be dried to a moisture content of 15% (grain) and 7%-8% for pods to avoid mould growth.
Utilization of groundnut
Groundnuts have a high nutritional value. They are rich in protein and minerals and are a good source of cooking oil. They can be eaten on their own or blended with other dishes to improve taste and nutritional value
Threats to production
Low yields in the semi-arid tropics are attributable mainly to the fact that groundnut is grown in marginal area under rainfed conditions and is subject to periodic drought. The crop is highly susceptible to contamination by some 20 different mycotoxins, including aflatoxin caused by a fungus Aspergillus flavus. Aflatoxin is extremely hazardous to human health and is especially harmful to the physical and mental development of young children. Over time, exposure to alflatoxin-infected foods can lead to hepatitis, immune system suppression and liver cancer.
The risks associated with aflatoxin contamination have led industrialized countries to establish rigorous quality standards that often deny farmers from developing country the opportunity to export. In West Africa for example, groundnut is largely produced by women and export prohibitions have important implications for family well-being and frequently prevent farmers from purchasing resources that might otherwise be used to increase productivity.