Linextester analysis of two testers of spring type and six lines of winter type rapeseed varieties were used to estimate combining ability and heterosis of phonological traits, plant height and grain yield. Significant mean squares of parents vs. crosses revealed significant heterosis for all the traits but linextester mean square which indicating the non additive genetic effects was only significant for plant height and grain yield. High narrow sense heritability estimates for phonological traits indicating the importance of additive genetic effects for these traits. Significant Specific Combining Ability (SCA) effects of plant height and grain yield were observed for only a few crosses. Most of the crosses had significant over winter and spring parents heterosis for all the traits, therefore heterosis of crosses is more reliable than SCA effects in winterxspring crosses of rapeseed. All of the crosses had significant negative over winter parent heterosis effects for days to flowering, days to end of flowering and plant. Significant positive over spring parent heterosis effect was displayed for days to maturity and plant height in most of the crosses, indicating, in compare to their spring parents most of F1 genotypes were tall and late maturity. Significant positive over winter and spring parents heterosis effects was observed for grain yield in some of crosses which had high performances of these traits.
Valiollah Rameeh , 2011. Heterosis and Combining Ability Assessment for Phenological Traits, Plant Height and Grain Yield in WinterxSpring Combinations of Rapeseed Varieties. International Journal of Plant Breeding and Genetics, 5: 349-357.