Management of pathogens and pests to maintain seed quality during storage

The post harvest losses in India is about 12 to 16 million tonne (Mt) of food grains each year, of which 7.5% losses occur during storage. Quality seed is the cheapest and most critical input in agriculture which alone can result in 15–20% increase in productivity but its production and storage needs utmost care. The important factors that determine the longevity of seeds are the seed moisture, type of storage container and storage environment; and their interaction leads to contamination with microorganisms or insect pests resulting in seed deterioration. Temperatures of 25–30°C and more than 13–14% moisture content at harvest provides ideal conditions for mould and insect infestation. Any mechanical damage during harvesting and threshing or insect infestation increases the susceptibility of the stored product to fungal contamination. A significant negative correlation (r = -0.872) between seed germination and mycoflora has been observed with increase in the storage period. Seed longevity can be maintained either by reducing/preventing the fungal inoculum or by creating unfavorable conditions for their growth. Management of pathogens and pests are essential both at preharvest and post harvest stages. Proper storage and application of safe chemicals prior to storage can effectively control seed mycoflora and insects, thereby reducing the storage losses considerably. Appropriate dressing with proper dose and its uniform distribution on the seed is equally important for seed treatments to be effective. Post harvest management of diseases through mechanical processing is another important, most economical and new option for obtaining bunt free grain/seed in wheat and paddy. Fumigation is one of the most effective methods to control storage insects, but its efficiency depends upon the type of fumigant, its dose, placement and the weather conditions.