Complete submergence is one of the most important abiotic stress constraining rice production in India. From the past few decades effect of this stress has intensified and is anticipated to increase in coming years as a result of global climate change. Rice has developed many adaptive mechanisms to grow well in flood ecosystems however, too much water for long time at any stage of plant growth can lead to serious injuries like decaying of plant parts, lodging and reperfusion causing total crop loss. Because of these conditions, farmers usually rely on traditional landraces that can survive through this stress, despite the fact that these tends to be very low yielding. In the present study, 660 rice landraces along with checks were subjected to screening for submergence tolerance at vegetative stage in target production environment. Identification of tolerant genotypes was based on the survival percentage of plants and recovery by which they grown new tillers and leaves. Principle component analysis revealed three principle components accounted for 99.9 per cent of total variation. Regeneration percentage of tillers found to be the most discriminating character and possess additive gene action. Confirmation through cluster analysis grouped the tolerant and susceptible genotypes in the respective clusters. Results of screening showed that, out of 660 accessions, three accessions viz., IC388692, IC377169 and IC205953 have highest tolerance to 14 days of submergence and the survival ability was similar to the tolerant checks FR13A and CO 43-Sub1. Apart from the above three accessions, eight accessions viz., IC216378, IC126210, IC114413, IC386238, IC133584, IC114971, RL-1312 and RL-3055 scored 1 for faster regeneration of tillers denoting the ability to have good tolerance for submergence stress.

Rice (Oryza sativa L.) is the main cereal crop cultivated throughout the globe the importance of rice can be judged by finding that rice alone caters to around half of the world's population. Therefore, studying rice in different environments is a need of time because of climate change which severely hampers crop production. Hence the study was carried out in 50 rice landraces to observe their phenotypical variability and diversity under a drought environment. Analysis of variance shows that a wide range of variability is present among the genotypes so further analysis of PCV (phenotypic coefficient of variance) and GCV (Genotypic coefficient of variance) was calculated to show the environmental effect on traits which was maximum in leaf area (46.66 and 45.55) total leaves per plant (39.88 and 37.45) and number of panicles (38.39 and 35.40). Correlation studies revealed that the drought scores, tip drying score and leaf rolling scores are significantly correlated to each other as well as to total leaves per plant (0.491), leaf area (0.491), number of tillers (0.6244) and number of panicles (0.8003); which are in turn significantly correlated to single plant yield. By clustering, all the 50 genotypes were placed in 11 clusters. Among all clusters, the cluster three is major cluster which contains a total of 18 genotypes. Maximum intracluster distance was found in cluster IV (929.08). Cluster V (90.25) observed the highest cluster mean for single plant yield. Drought score ranking method revealed that the cluster number seven has a genotype which is tolerant to drought. Based on the study the variability and the diversity among the genotypes were assessed under drought environment. Cluster number seven contains a genotype IC 216378 which has superior in performance under drought situation and selected as a best pre-breeding material for drought breeding programme.