Investigation of Salinity Tolerance in Spring Rapeseed by Line × Tester Method

In order to evaluate the salinity tolerance of spring rapeseed varieties, 15 hybrids obtained from the intersection of 5 lines and 3 testers with their parents (total of 23 genotypes) in two conditions of normal and salinity irrigation in two randomized complete block designs with 3 replications were studied in 2009-2010 at Kerman Agricultural and natural Resources Research Center. Significance of the effect of treatment on all studied traits (a total of eight traits) under two irrigation conditions showed that there was sufficient genetic diversity between crosses, which justified line × tester analysis. Decomposition of hybrids into their components based on line-tester analysis showed that the effects of lines, testers, and the effect of line-tester in terms of the studied traits were significant, and the lines had different reactions in combination with different testers. Estimates of more than one for the ratio of the mean squares of general combining ability to squares of specific combining ability showed that the additive action of genes has greater role in their genetic control. High values and low amplitude changes of broad sense heritability showed that genetic variance was greater than environmental variance. The lowest amount of specific heritability for the trait of 1000-kernel weight (58.74%), and the highest amount was related to grain yield (89.89%) under normal irrigation conditions. Crosses SPN179 × Dalgon and RGS003 × SPN179 are the best hybrids in terms of grain yield under normal and salinity conditions, respectively, with the highest values of specific combining and are recommended