Pune: When it comes to soybean, farmers are advised to sow freshly produced, certified seeds every season instead of seeds saved from previous harvests. Otherwise, farmers have to undertake costly resowing.Higher pre-harvest temperatures can affect seed maturity, while excessive rainfall during harvesting increases seed moisture. Delayed drying further accelerates deterioration. Frequent fluctuations between dry and humid weather during storage also shorten seed life.Scientists say rising temperatures and increasingly unpredictable monsoon conditions are making soybean seed preservation even more difficult. Other experts say careful handling throughout the seed production chain, from harvesting to warehouse storage, is essential to maintain seed quality.Satish Nichal, head of Regional Research Centre, Dr Panjabrao Deshmukh Krishi Vidyapeeth in Amravati, told TOI, “As climate variability increases, maintaining seed quality has become challenging for both seed producers and farmers.”Poor germination has become a recurring concern in soybean-growing states of Maharashtra, Madhya Pradesh and Rajasthan, particularly in erratic monsoon years.Sunil Borkar, director of quality control and inputs, told TOI soybean covers over 40 lakh hectares annually in Maharashtra, and a small decline in germination can translate into significant economic losses.“Plant population reduces, yields are lower and sowing expenses mount. We have registered over 80 FIRs against seed companies across the state to send a stern message to violators.”Nichal, who has developed four soybean varieties, said farmers should use certified seeds that undergo rigorous quality testing. Seed lots are tested for physical purity, moisture content, germination percentage and genetic purity. Warehouses maintain controlled storage conditions that minimise deterioration, he added.“Most certified soybean seed is supplied within one production cycle, ensuring that farmers receive relatively fresh seed with higher vigour. In contrast, uncertified or illegally stored seed may remain under uncontrolled environmental conditions for extended periods before reaching the market,” he added.Frailty of soybeanSoybean seed unlike wheat, chickpea, or pigeon pea, rapidly deteriorates under unsuitable temperature and humidity conditions. Agricultural scientists who have developed soybean varieties said nearly one-fifth of the seed has oil and 40% is protein. Both assets make it valuable for food and animal feed, but reduce its storage life.“The oil undergoes oxidation during storage. This gradually damages the seed cells and reduces their ability to germinate. At the same time, proteins and cell membranes deteriorate if moisture levels increase,” agriculture scientist Milind Deshmukh, who has developed three soybean varieties, said.Unlike cereals such as wheat or rice, soybean seeds lose vigour faster because the living embryo inside the seed remains metabolically active. Even when seeds appear healthy from the outside, internal deterioration may already have started, he added.Moisture sucks qualityThe seeds readily absorb atmospheric moisture because of their chemical composition. During India’s monsoon months, improperly stored seed can quickly cross the safe moisture limit, BU Dupare, principal scientist from National Soybean Research Institute, Indore, said.“When moisture content rises, respiration inside the seed accelerates. The seed consumes its own food reserves while fungi and storage moulds begin multiplying. As a result, the embryo weakens and the germination percentage drops sharply,” he told TOI.Agricultural universities recommend maintaining seed moisture around 9-10% for long-term storage. Even small increases in moisture can substantially reduce viability over several months. Storage temperature also plays a crucial role. High temperatures accelerate ageing by increasing biochemical reactions inside the seed.“Seed companies do not follow these norms and their seeds have ended up in poor germination this season,” a senior official from the state agriculture department told TOI.Deterioration long before seed bag is openedEvery seed contains living cells protected by delicate membranes. During prolonged storage under warm and humid conditions, these membranes gradually lose their integrity. When such aged seeds are sown, they either fail to germinate or produce weak seedlings incapable of surviving heavy rainfall or dry spells.“Farmers must sow only after receiving 70-100mm rainfall. The seed should not be buried or sown more than 3cm deep. In case it goes deep in to the soil, rainfall should be adequate enough to provide moisture for proper germination,” Deshmukh added.Laboratory tests often reveal leakage of cellular contents from damaged soybean seeds, indicating advanced membrane deterioration. “Many farmers believe that if a seed looks healthy, it will germinate well. Soybean deterioration is often invisible. The damage happens at the microscopic level long before any external signs appear,” a seed technologist working with a private firm told TOI.They are also highly prone to mechanical damage during harvesting, threshing, transport and packaging. “While transporting seed bags, we tell companies to use a rack system. Also, if farmers want to use their own seeds, they should sun dry them. The best method is to test 100 seeds in the backyard. If they see a good germination, then they should go for mass sowing,” Dupare said.The seed coat is relatively thin and cracks easily under mechanical impact. Hairline cracks may not be visible to the eye but allow moisture and pathogens to enter the seed. Mechanical injuries reduce germination and increase fungal infection during storage.
