Classification of mutant rice (Oryza sativa L.) genotypes under drought stress conditions

The present study was conducted in two separate experiments under drought stress and normal irrigated conditions using randomized complete block design with three replications at Rice Research Institute of Iran in Rasht, Guilan, Iran, during 2014-2015 growing season. Plant materials included 14 mutant lines (7 lines from Hashemi, 6 lines from Tarom and one line from Khazar) and four commercial rice cultivars (Hashemi, Tarom, Khazar and Gilaneh). Factor analysis resulted in five and four main factors for normal irrigated and drought stress conditions, which explained 81.5% and 79.3% of the total variation, respectively. The results indicated that under drought stress and normal irrigated conditions, selection of plants with high grain fertility (%) and panicle length and shorter plant height and internode length leads to increased grain yield. Cluster analysis classified the genotypes into five groups under both conditions. Discriminant function analysis indicated very high accuracy (100%) of grouping based on cluster analysis. The results of different analyses identified rice lines; TM6-230-VE-8-4-1, TM6-250-10-7-1, TM6-B-2-1-E and HM5-250-E-1-1 as superior genotypes with higher grain yield (2227.6 kg.ha-1) and the other desirable traits including high grain fertility (80.9%) and low panicle exsertion (6.3 cm) under drought stress condition. The average grain yield of these genotypes was 4739.9 kg.ha-1 in normal irrigated condition. Reduction of grain yield due to drought stress was 53% for these genotypes, and 60% for all of genotypes. Therefore, these selected genotypes can be considered in rice breeding programs to improve drought tolerance germplasm.