Effect of storage period on special DUS characters in extant varieties of rice (Oryza sativa) for establishing distinctiveness

Under the PPV and FR Act 2001, a number of rice varieties have been registered based on morphological and biochemical DUS descriptors. In the present study, 61 extant varieties of rice (Oryza sativa L.) were characterized based on 55 morphological descriptors at different stages of plant growth. However, for the assessment of biochemical characters, namely; phenol reaction of lemma, amylose content and gelatinization temperature, the assessment is based on ripened seed onwards, and even after the seed is stored. Hence, there is a need to determine optimum period after seed ripening for recording biochemical characters to avoid confusion during grouping of varieties for establishing distinctiveness. For this, all the 61 varieties were examined to see the effect of storage period on biochemical characters. The observations were recorded beginning from freshly harvested seed (0 months) vis-à-vis stored seed up to one year (12 months). The data were recorded after every three months up to a period of one year. Results revealed that significant changes begin to occur during six months of storage and continue for remaining period. Phenol reaction of lemma colour in 26 varieties showed significant changes in colour intensity after six months of storage. Gelatinization temperature (GT) and amylose content are important cooking quality traits for rice. Among 61 varieties, 26 showed increase in Gelatinization temperature after six months of storage as ASV decreased from 6.7 to 6.0, while the remaining varieties showed constant ASV. Further, the average percentage of amylose content significantly increased after six months of storage period in all varieties. Hence, storage period significantly influences the character expression of biochemical traits. Therefore, it is recommended that the varieties should be evaluated for the biochemical assessment within six months of harvesting.