Assessing Seed Vigor Characters of Selected Rice (Oryza sativa L.) Genotypes Using Accelerated Ageing Method

Rice (Oryza sativa L.) is an annual grass with the third-highest world production after sugarcane and maize. However, due to losses in vigor caused by poor seed storage, global consumption has surpassed production. Preservation of germ plasma both in-situ and ex-situ is the key to the conservation of rich biodiversity. Seed vigor is a key element of seed quality and high vigor seeds give uniform plants stand and higher yields per area. Accelerated ageing tests enable testing the vigor of stored seeds by subjecting the seeds to a particular temperature and relative humidity over time and then performing standard germination tests. Viability of most seeds normally reduces with the storage period, storage temperature and relative humidity. There is limited information on the duration of storage for rice seeds. Accelerated ageing is considered an excellent option as a vigor test when compared to seedling emergence and index of emergence speed because of the shortest time of acquisition and efficient results. Accelerated ageing tests at 0, 24, 48 and 72 hours (45ºC and 98% RH) were carried out JKUAT post-harvest laboratory using eight rice varieties’ in four replications of 100 seeds each. Data were analyzed using GENSTAT statistical package. ANOVA and T-tests at 5% significant level. Results showed that there was significant variation in both coleorhiza and coleoptile formation among rice varieties (p<0.001), treatments (p<0.001) and interaction between rice varieties and treatment (p<0.001). The difference between all treatments was significant with 72 hours’ treatment having the highest number of days to coleorhiza and coleoptile formation. The present study has shown that prolonged duration of higher temperatures results in a reduction of seed viability. The earliest coleorhiza formation was observed on day 2 and the latest on day 6. Results from this study will guide farmers and seed processors on considerations regarding storage period and storage temperature to ensure high-quality seeds.