Study of rice (Oryza sativa L.) lines tolerant to heat stress of IRRI by using multivariate statistical methods

Background and objectives: Evaluation of the grain yield and yield components and also morphological traits can help to identify strategies for selection of resistant cultivars and increased crop yield production under heat stress condition. To this end, in experiment to evaluate of grain yield and yield components on 42 rice lines tolerant to heat stress from International Rice Research Institute (IRRI).
Materials and methods: An experiment was conducted based on randomized complete block design (RCBD) with three replications plus Hoveizeh cultivar as control during 2013-2014 in Agricultural Research and Natural Resources Center of Khuzestan province, Iran. The evaluated eight characters were: degree of maturity, growth period, number of tillers per square meter, number of grains per panicle, number of hollow grains per panicle, 1000 grain weight, fertility percentage and grain yield measured on the basis of the standard system of International Rice Research Institute. As the degree of maturity of the product of two traits of fertility percentage and 1000 grain weight were measured in each trial.
Results: Research simple of traits variance analysis showed there were significant differences in effect of cultivar for all traits except number of tiller per square meter that this result showed that diversity of the lines and cultivar for using in the study. Number of tillers per square meter and number of grains per panicle in front of grain yield imported in regression equation that these traits of positive and significant correlation with grain yield. Path analysis showed that the number of grains per panicle with correlation coefficient of 0.337 had the higher direct effect than number of tillers per square meter with correlation coefficient of 0.186 on grain yield. Principal component analysis of the first two components explained 74% of the total diversity. In this analysis desirable characters such as fertility percentage, grain yield and degree of maturity in the first component have positive coefficient traits which increase first component, and also 1000 grain weight with negative factor coefficient in second component, so first component increased and second component decreased. Cluster analysis, case of study cultivar and lines resolved in three groups. In the first cluster, lines such as: 1, 34, 54, 35, 39, 21, 33, 40, 25, 28, 9, 10, 15, 29, 32, 31, 30, 36 and 44 as well as in the second cluster, lines such as: 3, 24, 4, 19, 5, 7, 6, 55, 14, 23, 16, 17, 18 and 20 and in the third cluster, lines such as: 8, 50, 52, 43, 41, 45, 11, 13, 12 and 26 were included. In the first cluster desirable lines were 40, 35, 34 and 25 and in second cluster undesirable lines were 11, 12, 13, 26, 41 and 45.
Conclusion: Significant differences in effect of cultivar for all traits except number of tiller per square meter that this result showed that diversity of the lines and cultivar for using in the study. According to graph of biplot the first cluster was as best cluster and third cluster was as worse. Discriminant function showed truth grouping at 95%.