Non-destructive Method of Seed Vigour Testing of Traditional Rice (Oryza sativa L.) Varieties Conserved in Genebank under Medium-term Storage Conditions

Abstract

Plant genetic resources are commonly conserved in the form of seeds in genebanks for their present and future use in crop improvement programmes. It is commonly understood that the loss in vigour, precedes loss in viability during storage. However, vigour tests cannot be conducted routinely for a large number of varieties processed for conservation and monitoring seed quality in genebanks. Hence, rapid and non-destructive tests will be immensely useful to provide additional information during monitoring of seed samples. The seeds of 31 traditional varieties of rice, conserved in medium-term storage (MTS) module (4°C and 35% relative humidity) at ICAR-National Bureau of Plant Genetic Resources, New Delhi, for past 10 years, were used to assess the seed quality by recording the germination percentage, mean germination time, seedling length and vigour index I, electrical conductivity, potassium (K+) and sodium (Na+) ion concentration in leachates. Results of the study clearly confirmed the fact that K+, Na+ ion concentrations in leachate and K+/Na+ ratio can be used as reliable and non-destructive method of vigour tests for assessing the quality of rice seeds. Several varieties with similar high percentage of initial germination deteriorated drastically leading to highly variable germination percentages after 10 years in MTS, indicating genotype-specificity.