Qualitative Morphological Characterisation and Assessment of Genetic Diversity among Indigenous Landraces of Rice (Oryza sativa L.)

Abstract

The present study evaluated morphological diversity among 254 rice accessions, comprising 250 indigenous landraces and four checks (IR 64, JR 206, Improved Jeerashankar, and Improved Chinnor), using qualitative DUS descriptors and the Shannon-Weaver Diversity Index (SWDI). The study aimed to identify variable traits that could support varietal documentation, germplasm characterisation, and use in rice breeding programmes. The accessions showed substantial variation in several reproductive, panicle, awn, pigmentation, and grain-related traits, whereas some vegetative traits were conserved. Leaf collar and ligule presence were monomorphic, with 100% occurrence and no diversity (SWDI = 0.00). Leaf auricle and anthocyanin pigmentation of the nodes and internodes also showed limited variation. The highest diversity was recorded for panicle length of the longest awn (SWDI = 1.55), followed by awn colour (SWDI = 1.43), spikelet colour of the lemma tip (SWDI = 1.41), lemma and palea colour (SWDI = 1.40), and flag-leaf attitude at late observation (SWDI = 1.32). Panicle branch attitude was also variable, with semi-erect (40.94%), erect (30.70%), and erect-to-semi-erect (17.32%) types predominating. Moderate diversity was observed for culm attitude, spikelet pubescence, stigma colour, panicle exertion, sterile lemma colour, and secondary branching intensity. Overall, SWDI values ranged from 0.00 to 1.55. The highly variable qualitative descriptors identified in this study may support genotype identification, DUS characterisation, germplasm conservation, and the selection of diverse parental material for rice improvement programmes.