Evaluation of Seed Yield and Related Components of Rapeseed Winter Cultivars Under Different Sowing dates in Karaj area

Sowing date is the most important factor on yield and it's components of rapeseed. Suitable sowing dates make the environmental conditions during the days of emergence and seedling establishment favorable for plant. This experiment was conducted in split plot layout with randomized complete block design with four replications at seed and plant Improvement Institute (SPII) during 2000–2002 years. Main plots were sowing date with four level of: 6/20, 6/30, 7/9 and 7/19. Sup-plots were rapeseed varieties including SLM046, Zarfam, Colvert and Orient. The traits evaluated were: Plant height, number of branches, number of pods per plant, number of seeds per pod, 1000 seed weight, seed yield, oil contain and oil yield. Combined analysis of variance showed that sowing date had very significant effect on seed yield, oil yield, number of pods per plant, number of branches and 1000 seed weight. The highest yield (3295 and 2877 kg/ha) was in the first planting time (6/20) and the second planting time (6/30) respectively. Variety effect was highly significant only for number of seeds per pod and 1000 seed weight. The highest number of seeds per pod was related to SLM046 and Orient varieties (24.3 and 24.2 respectively). Interaction between sowing date and variety was significant only for number of branches and number of seeds per pod (

Genetic analysis of grain yield, days to flowering and maturity in oilseed rape (B. napus L.) using diallel crosses.

Abstract Twenty one F 2 progenies derived from a 7×7 diallel crosses along with parents were evaluated for grain yield, flowering and maturity time. Due to significant genotypic effects for all traits, genetic analyses were performed on F 2 progenies including analyses of combining ability and genetic components. The Analysis of variance revealed that both additive and non-additive genetic effects were involved in controlling these traits. GCA/SCA ratios were 0.91 for days to flowering, 0.95 for days to maturity and 0.83 for grain yield which indicated that the additive gene effects were more important than non-additive gene effects for all these traits. Narrow-sense heritability was high for days to flowering (73.12%) and days to maturity (81.99%) and low for grain yield (30.15%). Heterosis in hybrids seemed to be largely determined by complementary epistasis as well as genetic distance between the parents. The spring-type varieties Tower and Regent appeared as the best parents for earliness whereas winter-type varieties D.R. and Ceres were best parents for high grain yield. It could be concluded from the study that S 1 recurrent selection would be effective to improve the performance of these genotypes for grain yield, flowering and maturity time. The selected S 1 lines from each cycle can be used in a pedigree-breeding program to identify superior genotypes