Genetic Divergence Study in Different Rice (Oryza sativa L.) Genotypes under Irrigated and Drought Stress Condition

Thirty rice genotypes were evaluated to study genetic divergence under irrigated and drought stress conditions in randomized block design at Bagusala farm, M. S. Swaminathan School of Agriculture, CUTM, Odisha, during summer 2019. The main objective of this experiment was to identify reproductive phase drought tolerant genotypes through study the effect of drought stress on yield, yield attributing and biochemical traits performance of selected genotypes using Mahalanobis D2 statistics. Set of 30 genotypes were grouped in to five and nine clusters under irrigated and drought situation. Under irrigated conditions cluster-Ⅰ was largest cluster with 22 genotypes followed by cluster-Ⅱ includes 5 genotypes cluster-Ⅲ, IV and V each consisted with only one genotype. Under drought condition, genotypes were grouped into nine different clusters, cluster-Ⅰ was the largest cluster involving 20 genotypes followed by cluster-Ⅱ having 3 genotypes whereas, cluster-Ⅲ, IV, Ⅴ, Ⅵ, Ⅶ, Ⅷ and Ⅸ were recorded with single genotype. The maximum intra cluster distances under irrigated conditions were found in cluster- Ⅱ (27111.9) followed by cluster-Ⅰ (17587.7). Whereas, in case of stress cluster-Ⅱ had maximum distance (21110.9) fallowed by cluster-Ⅰ (17957.8). Under irrigated maximum inter-cluster distances recorded between cluster-Ⅱ and Ⅴ (62310.8) followed by cluster-Ⅳ and Ⅴ (57656.0). In case of stress maximum inter cluster distances recorded between cluster -Ⅱ and Ⅶ (69865.5) fallowed by cluster- Ⅷ and Ⅸ (67848.9), cluster-Ⅱ and Ⅸ (65239.2). Under irrigate conditions highest manifestation towards genetic divergence was exhibited by chlorophyll followed by plant yield, 1000 grain weight, proline, number of spikelets, carbohydrates, grain weight, phenols, panicle length, panicle weight, flavonoids, number of filled grains, plant height and number of tillers. In case of drought stress, maximum percentage contribution towards to the genetic divergence was observed for Proline followed by carbohydrates, plant height, plant yield, grain weight, chlorophyll, number of spikelets, flavonoids, 1000grain weight, filled grains, phenols, panicle weight, panicle length and number of tillers, while other trait like root length did not contribute to the total divergence. The genotypes grouped under cluster Ⅰ, Ⅲ, Ⅴ, Ⅷ namely MTU1010, MTU1075, MTU1224, RNR2465 and Manipur black rice exhibited maximum drought tolerance under stress conditions. These genotypes can be used as the donor parents for development of drought tolerant lines in crop improvement programme.