Genetic Analysis of Yield and some Important Traits of Oilseed Rape under Noraml and Delayed Planting Conditions

Development of high yielded varieties is important to balance between production rates and grewing food needs of human population. For genetic analysis of yield and some important traits in oilseed rape (Brassica napus L.), We conducted line×tester analysis with ten lines and ten testers (three winter parents and seven spring parents). First generation hybrids as well as 20 parents (120 genotypes) were cultivated as a alpha lattice design with two replications under two different conditions (normal and delayed planting date) and days to flowering, flowering duration, plant height, number of primary branchs in plant, thousand seed weight and yield were studied. The results showed that the difference between genotypes is significant and the environment had a different effect on genotypes. High levels of broad sense heritability (from 73.65% for number of primary branches in plant to 87.65% for grain yield) showed that the genetic variance was more than environmental effect. Estimation of less than unit for the mean squares of the general combining ability to the mean squares of thespecific combining ability ratio and low to moderate value of narrow sense heritability (from 29% for plant height to 70% for grain yield) showed that non-additive variance is the major factor in controling of studied traits. The spscific combining ability of hybrids and hetero estimation showed that introduced hybrids in this study could be successfully used in breeding programs and improve the oilseed rape traits. The T9 × L2, T3 × L2, T3 × L9 and T3 × L5 hybrids in normal condition and T3 × L5, T7 × L6, T5 × L10 and T7 × L7 in delayed planting conditions with maximum heterosis for yield were potential hybrids for using in breeding programs for increased yield.