optimizing planting dates for canola cultivation in arak using meteorological data and simulation models

Due to water scarcity and the prevalence of rapeseed diseases such as phoma, blackleg, and alternaria blight, along with severe cold in late autumn and winter, the physiological stages of seedling establishment and the rosette phase of rapeseed face numerous challenges in the climatic conditions of arak. in recent years, dormant sowing has been recommended as a new method for certain crops, but this approach may not directly benefit rapeseed. therefore, selecting the precise sowing date is crucial to prevent cold damage and to avoid the impact of late autumn and winter precipitation on rapeseed germination under arak s climatic conditions. in this method, the seeds are sown in late autumn or early winter when the temperature is low enough to delay germination until spring. as temperatures rise during the growing season, enabling seed germination, the seedlings emerge, and no delay occurs in the plant s spring growth due to soil preparation and sowing. in dormant sowing, selecting the appropriate sowing date is vital for plant survival. early sowing can lead to seedlings emerging from the soil, which may be killed by winter frost; thus, seed coating is used to prevent premature sprouting. on the other hand, delayed sowing can result in frost or heavy rainfall preventing the entry of planting machinery into the field. in this study, a rapeseed germination simulation model was implemented using 37 years of daily meteorological data for arak. seventeen sowing dates, from october 2 to march 15, were evaluated as dormant sowing dates, along with four spring sowing dates in april. based on the results of the model for these sowing dates, it is recommended that coated seeds be sown in arak between december 6 and 11 at the earliest opportunity.