Baruah, AiswaryaKalita, Mridusmita2024-07-182024-07-182023https://krishikosh.egranth.ac.in/handle/1/5810212166Rice (Oryza sativa L.) is one of the most important cereal crops. Increasing rice production is constrained by various stress and drought is one of the major limiting factors. For future food security assessments of genetic resources are necessary. North east India is the home of many indigenous rice varieties that are traditionally cultivated and maintained by farmers. Indigenous varieties contain a high level of genetic diversity and can serve as potential genetic resources for improving yield, and resistance to various biotic and abiotic stress conditions. The genetic architecture of diverse germplasm can be precisely estimated by assessing the structure of the population using molecular markers. Simple sequence repeat (SSR) markers are highly informative, codominant and reproducible. The first objective of this study was to assess the genetic diversity of a few indigenous rice germplasm using SSR markers. Out of the total of 28 SSR markers screened, 16 were polymorphic across twenty-seven genotypes with PIC values ranging from 0.076 to 0.499. The genetic diversity of rice germplasm under study was estimated by the Jaccard similarity coefficient. The phylogenetic tree, using unweighted neighbor-joining (UPGMA) drawn from the analysis divides 27 genotypes into 3 clusters. In the second objective, 9 genotypes were further characterized by exposure to drought stress compared to the control condition. Plants were grown in PVC pipes and subjected to drought by withdrawing water at 45 days after showing (DAS) for 25 days. After that plants were uprooted and a comparative study was done for a few morphophysiological parameters i.e. root length, root biomass, root-shoot ratio, root length density, chlorophyll content etc. It was observed that genotype Dehangi followed by N22 and Shahabhagi showed the best performance for all parameters under drought stress. This information will help in the selection of varieties with better root characteristics for drought tolerance in future breeding programs.EnglishThesis