The response of canola (Brassica napus L.) and mustard (Brassica juncea L.) genotypes to winter sowing dates in Gorgan area for dry matter accumulation and harvest index

In order to evaluate the effect of winter sowing dates on dry matter accumulation and harvest index of canola (B. napus L.) and mustard (B. juncea L.), an experiment was conducted at Agriculture and Natural Resource Research center of Golestan in 2009. The experiment was a spilt plot design, arranged an RCBD with 3 replications. Four sowing dates (January 5, January 20, February 5 and February 20) were main plots and four genotypes Hyola401, RGS003 (canola), and Bard1 and J98 (mustard) were sub plots. Results showed that delay in planting, caused reduction in the shoot dry matter and harvest index in all cultivars under study. The shoot dry matter of mustard genotypes was higher than the canola genotypes in all planting dates. Despite high levels of shoot dry matter of Mustard genotypes, harvest index and grain yield was lower than those of the canola genotypes. The yield of mustard and canola genotypes were 1433 and 2193 kg per hectare and harvest index of them were 14.07 and 23.87 percent, respectively. The lower seed yield and harvest index of mustard might be attributed to lower allocation of dry matter to seeds during filling period. The results of this study showed that under winter sowing dates, mustard genotypes unlike canola genotypes were not suitable for sowing in Gorgan area.