Assessing Iranian recombinant inbred rice (Oryza sativa L.) lines to salinity stress at vegetative stage

Salinity is one of the limiting factors in many crops including rice production. The objective of this study was to investigate the response of 89 recombinant inbred lines derived from a cross between two Iranian rice cultivars, Tarom-Mahalli (indica) and Khazar (indica), under non-stress and 8 dS.m-1 salinity stress at vegetative stage conditions. The experiment was carried out as pod experiment under open air conditions in a completely randomized design with four replications. The results of combined analysis of variance under non-stress and salinity stress conditions showed that the the effect of line and line×stress interaction for all the studied traits was significant, indicating different reaction of the lines under two conditions. The results of simple analysis of variance also showed that the difference between lines in both conditions was significant for all traits at 1% probability level. Correlation coefficients among traits indicated that the highest correlation coefficient was observed between biomass and stem dry weight under both conditions. Stepwise regression analysis for biomass under non-stress conditions showed that root length, root to shoot dry weight ratio, number of tillers per plant at 120 th day and plant height at 120th day were the most important traits influencing biomass, respectively, while under salinity stress conditions, root area and root volume in addition to these four traits, were also identified as effective traits on biomass. Factor analysis also showed that three and five independent factors explained the correlation between biomass and the other traits in the studied lines under non-stress and salinity stress conditions, respectively. Cluster analysis using Ward’s minimum variance method under non-stress conditions divided the lines into four groups which the fourth group was consisted the lines with higher values than total average for most traits. Under salinity conditions, the lines were divided into three groups and the lines into first group had the highest biomass and the lowest genotypic score and were tolerant to salinity stress. In total, the results of current study showed that the lines 6, 9, 13, 14, 17, 18, 23, 24, 34, 39, 44, 45, 68, 79 and 80 had the higher values for most the studied traits than the other lines, in addition to higher biomass, and could therefore be considered as salinity tolerant lines in future researchs.