A serious issue to the Government all over the country for safe storage under hygienic conditions
Pakistan is facing grain storage problems at large scale throughout the country, due to either traditional methods of seed storage or short of commercial grain storages and their management. The people often store their grains in godowns due to protection from hidden enemies like birds, rats and insect pests, which cause time to time damage to the seed.
Food grain storage is sensitive problem for the Farmers, Grain merchants and is a serious issue to the Government all over the country for safe storage under hygienic conditions. The increase in production of major commodities like wheat, rice, cotton and oilseeds of traditional and non-traditional varieties has emerged dramatic services problem of retention for long period. The existing storage facilities available are insufficient at various level to come with large increase in production.
The storage of wheat and rice and seeds of pulses and oilseed crops due to food value is important. There are seed hazards which occur due to poor storage facilities. Wheat is only a grain crop that is produced with low-cost technology due to minimum use of pesticides except the inputs such as seed, fertilizer and farm machinery etc. While crops like Rice, Cotton and Sugarcane are cost effective and need proper care for handling and storage. Thus, hundreds of thousand of tonnes of wheat and other food and cash crops. Such as Rice, Sugarcane and Cotton, oilseeds and pulses had to be stored in temporary facilities that afforded inadequate protection and pilferage.
The self sufficiency in food grain and adequate arrangements for its storage go hand in hand. The ancient history showed the arrangements for the storage of grain made by prophet of God Hazart Yousif, when a worst famine hit Egypt for seven years. The prophet Hazrat Yousif was appointed as the officer incharge over the storehouses of the land as he was skilled custodian of food grains.
BASIC CONCEPT OF SEED STORAGE
The storage is the practice of keeping seed in store houses, heaps, bulks and bags in such a way that seeds should retain both food and seedling value, provided with certain conditions like ventilation, fumigation and optimum temperature and humidity etc. Whereas, the purpose of storing seeds is to preserve planting stocks from one season until the next.
In cereal crops, post harvest losses are divided into two parts, where first kinds of grain losses start from birds, rats, insect pests and diseases, rain, delay in threshing and storage etc. The losses of grain depends upon crop variety, grain moisture content, humid climate and high temperature. Whereas such grain losses may be reduced by threshing, cleanings, drying and storing of grain immediately after harvest of the crop. The moisture content should be brought at 10-12% before storage.
The proper storage of wheat grains depends upon timely harvest and post-harvest practices including threshing, cleaning and drying of seeds. The wheat grains are obtained from golden ears of this crop, which is sign of ripening due to rise in temperature in early summer days, that are days of maturity. Wheat grain harvest must be started in a well planned manner to avoid the rainy season. This is amongst the good struggle of farmers who manage to produce high yields of the best quality wheat. The most important steps which will come up to store the grain without their spoilage of viability and nutritional value.
The dry wheat grain is one of the objective to have proper procedure of storage to reduce chances of grain spoilage. However, admixture or any adulteration in the grain including trash, straw, dust, soil particles and grovels, may increase chances of store grain pest attack. The storage losses due to insects, rats and moulds go upto 10-18%. The seed quality is affected at many stages such as weather condition before harvest at maturity, the condition between harvest and processing, storage condition and pest problem in storage and precaution in the causes of losses in storages may be of transport pre-storage, storage and post storage nature. Where seeds are either admixtures, eaten by rats and other pest, destroyed by insect pests, moulds, seeds may be heated up and loose viability and germination capacity, which adversely affect the next year sowing. The seeds also carry infection and serve as source of disease for next crop.
The harvested material of any seed or variety should be kept separately in a bulk to avoid admixtures of seed. The precautionary measures must be taken during threshing and cleaning of seeds. The seed graders and sieves may be used to clean and screen out inert matter and small or undersize seeds for maintaining seed quality. Such harvest and post-harvest practices lead to the grains which are clean and free from inert materials. The proper storage of seeds under hygienic condition is a measure for quality control. The storage period starts from physiological maturity of seed to the time germination begins. During this time period, a serious to complete deterioration in seed quality can occur at such stages and seeds may lose their viability. The basic reason for various storage practices is the effort to maintain the physiological quality of seed by minimizing the rate of deterioration.
The hazards may occur because of improper ventilation, lack of control over temperature and humidity, high moisture content in seeds, lack of control over rain due to broken walls, floors and ceilings, spoil and uncleaned Godowns, use of old bags, patches of insects and fungus, lack of spray and fumigation etc. Which results in increase number of dormant seeds, sprouting, moulding and rotting, increase of insect damage and bird contamination. However, chemical and biological changes like loss of germination, development of acidity, gluten deterioration and loss of nutritive quality, may also occur.
STORAGE PROBLEMS
* Low capacity stores.
* Use of local Mud bins for storage.
* Uncleaned and filthy store houses.
* Improper ventilation, leaky and dampness in store houses.
* Inconvenient storages (with broken walls, ceilings and floors).
* Unproof store houses to insect pests, rodents and birds.
* Stores are unproof to gas .
* Improper spray and fumigation to store houses.
* Use of old gunny bags.
* Seed storage in open bulks and heaps.
* Rain hazards.
* Insect nest and disease problems in store houses.
* High temperature and humidity problems in stores.
* Storing seeds with high impurities (including inert matter, dead bodies of insects and fungus).
* Unhygienic conditions of stores.
OLD AND NEW STORAGE SYSTEM
The safe grain storage is dependent upon safe environment. The ecological and climatic conditions in different parts of the country consisted a warm and humid climate, which is inclined to all kinds of biological and environmental hazards in stored grains. There are certain new methods and techniques developed that decrease the rate and chances of grain spoilage. The establishment of seed cleaning and drying machineries, storage buildings, ware houses, silos, store rooms, outside piles or bulks etc which can be used for keeping stored grains dry and hygienic.
In rural areas of Pakistan, farmers still use Bins or gundis, palis, kotha, khumba and barolla etc for the storage of food grains on small scale, which are easy in handling and maintenance in terms of store grain pest control. But, on commercial level, warehouses, godowns, bunker, tower silos and flat-type concrete storage buildings are used for storage purposes. Such type of storages are well equipped with ventilation facilities for passing of air through the grain and control the temperature to keep them dry.
In old system, small-scale farmers use clay or mud silos for this purpose. Whereas, cylindrical metal bins are hard and are better in preservation of grain quality, and are cost effective and durable. At the time of selection of storages, some factors must be considered to keep grain dry, withstand grain pressure (means more capacious for storage), and ease of in-out movement of grain, which determines the filling and emptying of the storage resource. This all depends upon how economical is storage for grain storage purposes. If the storage costs are higher than farmer capacity, it would be impossible for small-scale growers to utilize such facilities.
The betterment in handling and storage of agricultural produce by the use of modern scientific and technological principles will reduce losses and improve the quality. The losses as a result of faulty harvesting and handling methods, and above all of bad storage are often under rated. Such losses might go upto 100% for produce that is entirely spoiled due to lack of proper storage facilities.
However, a small cost and a little effort in this regard, can save a lot of foreign exchange, and prevent grain spoilage through proper planning and implementation strategies by educating farmers to use scientific methods. The commercial Government storages are more capacious with proper ventilation, control over temperature and humidity, and are insect pests rodent and bird proof.
The seed is key element of the agricultural system, which depends upon certain factors for establishing seed quality including purity, germination capacity, vigor, seed size and health. A large quantity of seed is damaged by fungi and insect pests during storage, if not handled properly. After harvest and drying the seed is packed in gunny bags and/or stored in Godowns properly. The moisture content of seed should not exceed 14%. The seeds maintain their vigor and germination capacity for a period of weeks to years only if storage conditions fulfil the particular requirements for safe storage of seeds. The storage life of cereal seeds stored at different seed moisture contents may be as under:
SEED MOISTURE CONTENT. | STORAGE LIFE |
11-13 | six months |
10-12 | one year |
9-11 | two years |
8-10 | four years |
The germination and vigor are influenced by the storage conditions under which farmers store their seeds at village level. When the farmer store his own seed, only small quantity is stored at home or on the farm. At the mean time, some quantity of seed has to be carried over for coming years. The purpose of storage is to maintain the germination capacity. The life of seed comes to an end, when the germination capacity begins to fall. The hard coat seeds such as peas, beans, Alfalfa, Beet, Maize, Millet etc have long storage life.
SAFE STORAGE CONDITIONS
For least seed damage in storage, the seed should be properly kept dry and cool to maintain its viability after the required storage period. Seed respires, which produces heat and moisture. It also absorbs heat and moisture from its surroundings and this cause deterioration of the seed. For safe storage, temperature, humidity and moisture content of the seed should be kept minimum. There are some factors affecting seed storage and longevity which include temperature, humidity, air or gases (Oz and COz) light, kind of seed, seed coat, maturity and dormancy of seeds, seed treatment, fumigations etc. The seeds may be stored safe at 5 per cent moisture content with a temperature of 18°C or less. The storage under such conditions, the loss of viability is very low. Whereas, life of seed decreases as storage increase from O to 50°C, each 5°C increase in storage temperature normally halves the life of seed.
The low temperature prolongs seed life, therefore temperatures in storage areas should be kept as low as possible, in view of storage period and economic value. The temperature range of 21-27°C is most conducive to insect and fungal activity. In a general phenomenon, temperature and humidity account much for the life span of seed. The seeds containing high moisture are more susceptible to damage at high temperature. If seeds come into contact with moist air, their viability deteriorates sooner than if they are kept in dry storage. The cereal seeds should never be stored with 14% or more moisture content, but for ideal storage moisture content below 9% is necessary. There are two sample rules which quantify the effect of moisture and temperature on seeds. (1) For every decrease 1% in seed moisture content, the life of the seed is doubled. (2) For every decrease of 5°C in storage temperature, the life of the seed is doubled. The high moisture content in the seed accelerates respiration causing accumulation of toxic wastage products, resulting in loss of viability.
However, the moisture content of seed depends on its chemical composition. The starchy seeds readily absorb and retain moisture and seeds to have high moisture content. Whereas oilseeds on the other hand, neither absorbs nor retain moisture content. It is observed that high moisture containing seeds deteriorate faster and are more susceptible to damage from extreme temperature, storage fungi, insects, heating and mechanical injury. Whereas, at high relative humidity, the life of seed is reduced, while the viability capacity decreases and number of abnormal seedlings increases.
The seed is a source of food for insects, rodents and other living organisms. A sufficient quantity of seed is damaged by fungi, insect pests and rodents. The larger part of grain loss may be saved by certain methods. Thus, the stored seed can never be quite as good as it was before storing, so if poor seed is stored, it will be even poorer in quality at the time of sowing.
The fungi adversely affect the quality of grain, through increase in fat, acidity, reduction in germination, mustiness and finally spoilage of grain. Some species of Moulds, produce toxins on cereal- grain under certain favourable conditions, which is responsible for human hazards and death of animals, after their use as food.
The stored grains are damaged by many insects which due to their small size and stealthy habits, remained hidden in the seed. The insects like Grain weevil, Red flour beetle, Grain moth, Sawtoothed grain beetle etc. are important store-grain pests, which cause great damage to the grain by eating away embryo of grain or seed.
Precautionary measures for safe storage
* To maintain high standard of godowns cleanliness. Where the proper cleaning of storehouses should be done and rubbish should be wiped out.
* The seed to be stored should be sound, healthy and free of trash.
* Store house should be at such a place where grain remain safe from insect pests, rats and humidity.
* The mud plaster should be done at least one month before storage of grains, by cementing ceiling cracks and leakages.
* The proper ventilation for air crossing should be maintained in store houses.
* The seed must be dried before storage in the godowns and store houses must be kept dry and well aerated (it means the seed and storage area should be kept dry) before use.
* The moisture content of seed should be minimized upto 8-12% or below, for safe storage purposes.
* The storage area should be safe from rain.
* Pest control must be ensured at adequate level in the storage area.
* Use of rodent and bird proof godowns having controlled ventilation, high plinth and leakage free floors, doors and windows. The slope should be given to the floors of the store for removal of water.
* The bags should be kept on the raised floor or high plinth of the stores. The bags should not come in direct contact with floor which may damage the seed.
* The insect pest proof gunny bags should be used for storing seeds.
* The old bags must be avoided and new ones should be dried before use.
* If old gunny bags, cloth bags and containers are required to be used to store seed, the same should be fumigated.
* The bags should be kept in row stacks at high plinth build up by bricks.
* The fumigation in storehouses needs air tight arrangements.
* The coal smoke should be diffused in the bins, palis and store houses while keeping the doors off for killing the insect pests.
* The spray and fumigation of the storehouses should be done well before grain storage. Before storage of grain, the Godown must be disinfected by spraying Malathion (50% EC).
* The wheat grains stored in bins and bags should be added neem leaves as natural repellant, which must be dried first under shade before use.
* The stores should be provided with electricity, offices and staff facilities.
* The storage area should not be heat trap. The temperature should be low if necessary to keep the storage as cool as possible.
* Before storage of grain, the Godown must be disinfected by spraying Malathion (50% EC).
* The periodical inspection of the seed should be carried out and control measures must be taken to avoid losses.
* The measures for keeping in and taking out grain, easy access and inspection of grain in the store houses and control over incidence of fire should be properly managed.
By Dr. Shamsuddin Tunio*
Associate Professor Department of Agronomy, Sindh Agriculture University, Tandojam.
Sep 09 – 15, 2002
