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. 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 ۳۷ years of daily meteorological data for Arak. Seventeen sowing dates, from October ۲ to March ۱۵, 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 ۶ and ۱۱ at the earliest opportunity. Poor crop establishment has significant global consequences on livelihoods and food security. Studies in France report low seedling emergence rates, leading to costly re-seeding for farmers. Seed germination, emergence, and establishment depend on genetic, environmental, maternal, and post-harvest factors. Biotic and abiotic stresses further affect success in the field. Effective management strategies are critical for crop establishment, which is influenced by interactions between genotype, environment, and farming practices. Canola (Brassica napus L.), a major oilseed crop, faces early-season challenges, including poor seedbed preparation, pest pressure, and abiotic stress, resulting in stand failures that reduce biomass accumulation and yield while increasing the need for inputs like pesticides and fertilizers. Canola establishment success depends on seed genetics, agronomic practices, and nutrient availability. Dormant cultivation, where seeds are sown in late autumn or early winter, is an increasingly popular strategy. This method helps crops germinate in early spring, avoiding delays caused by rainfall. However, the timing of sowing is crucial, as delays may lead to frozen soil or rain affecting planting. Given climate variability, long-term meteorological data and simulation models are essential for determining optimal sowing dates. This study focuses on identifying the best sowing time for dormant cultivation under Arak's climatic conditions.

کلیدواژه ها:

Dormant sowing ، Climatic conditions ، Cold stress adaptation ، Sowing date optimization