Canola as affected by sowing date In Iran region

摘要

The work reported in this paper examines yield altering on under different sowing date in Iranian regions of Brassica species.Sowing date is an important determinant of yield in canola. However, the decline in yield with delayed sowing has been poorly defined for different environments. We show from collated published studies and sowing date studies carried out on canola in the all cropping region in 1998-2003, that the decline in yield with delayed sowing is highly variable from -10% to +4% per week delay in sowing. The mean value 7% per week delay in sowing date agrees well with that already published. studies for one location are used to highlight the risks associated with sowing early to avoid end-of-season high temperatures and water deficit,which depresses seed yield and oil concentration, and sowing later to lessen the risk of damaging frosts during rosette and early grain-filling.