Identification of drought stress tolerant genotypes in external rice germplasm using GGE biplot graphical technique under drench and drought stress conditions

Rice is the staple food for approximately half of the world population. It is the basic food crop of Asia, providing over 30%-60 of the calories consumed in the region. Among abiotic stresses, drought is a major one, especially in arid and semi-arid areas. Evaluation of genotypes in drought stress conditions can increase our knowledge about the characteristics and traits that are effective in tolerance to water stress. Today, new graphical techniques are used to examine the effect of traits with respect to their interactions. One of these methods is GGE biplot. Although the GGE biplot was originally created to parse the data from multiple environments. However, this strategy, also, can be equally used for all types of 2-way data that assume an entry × tester structure. Considering the high water requirement of rice and lack of water resources the present study aims to investigate the relationship between traits and identify high yield tolerant genotypes in two conditions (flooding and drought) with 23 morphological traits in Gonbad-e-Kavous area designed. The materials used in this study, 263 genotypes of rice (Oryza sativa L.) were provided by IRRI (International Rice Research Institute) as a joint international project between the institute and Gonbad-e-Kavus University. The lines were evaluated in two separate experiments in the form of Latis design under normal conditions and drought stress in three replications. Each of 263 lines was cultivated in 2 meter and 25 centimeter meter square. 40 days after transplantation irrigation was cut and after 40 days, the subsequent irrigations were applied every 15 days. After complete sampling, the marginal effect was taken and 10 plants per line were harvested and transferred to the laboratory for measuring the traits. 23 morphological traits were measured and recorded according to the standard guidelines for evaluation of rice traits. The data obtained from this study was evaluated using SAS Ver.9.1 and GGE biplot (Yan, 2001) software. Due to the lack of significance between block changes in the Latis design, the data were analyzed using randomized complete blocks. The results of combined analysis of variance revealed that the effect of the environment, genotype and genotype × environment interaction were significant (p<0.01) for most measured traits. The biplot explained 41 and 46% of the total variation of standardized data for irrigated and rainfed (drought) conditions, respectively. Comparison of genotypes for the leaf rolling score showed that no strain was observed in non-stress conditions, but in drought stress conditions, leaf rolling score increased, depending on genotype susceptibility to drought stress. The highest rank (rank 7) belonged to genotypes 42, 44, 154, 194 and 199, and the lowest rank were genotypes 18, 63, 66, 77, 88, 98, 100, 102, 105, 107, 115, 167, 237, 310 and 312 respectively. The polygon view of Biplot from the interaction of genotypes in traits genotypes 118, 257, 88, 241, 289 and 154 introduced as an index genotypes for different traits in flood conditions. In drought stress conditions, numbers 63, 167, 201, 194, 199, 42 and 263 were identified as index genotypes. In both conditions, positive relationships were observed between traits. Comparison of genotypes based on plant yield with plant height and day to flowering showed that genotypes with higher grain yield had less flowering days and plant height. Therefore, it could be concluded that days to flowering and plant height had a negative correlation with grain yield. The results of this study showed that drought stress increased leaf rolling, increased number of days to flowering and reduced the majority of traits, especially plant yield. According to the results of graphite biplot analysis irrigated conditions, genotype HHZ 10-DT5-LI1-LI1 had the highest yield and stability and IR13F402 genotype had the lowest grain yield. In drought stress conditions, HHZ 3-SAL4-Y1-Y1 genotype had the highest performance and the second highest stability, HHZ 18-Y3-Y1-Y1 genotype was the most stable. Both genotypes were tolerant genotype and IR 11L412 genotype kknown as susceptible genotype.