Abstract
INTRODUCTION: Determining the optimal sowing depth suitable for different water conditions is a key agronomic factor for crop establishment and yield potential. This study aimed to identify the optimal sowing depth for rapeseed that maximizes seedling vigor under varying water conditions. METHODS: Seedling emergence and plant growth were evaluated under four water conditions (variable moisture, drought, normal water, and waterlogged) at different sowing depths (1-5 cm). Meanwhile, the hypothesis that seedling vigor under deep sowing conditions could be improved by exogenous application of glucosinolates (GS) was tested. RESULTS: Results indicated that the highest seedling emergence percentage (EP) was observed at 3 cm, representing increases of 123.2% (variable moisture), 100% (drought), and 11.1% (normal water) compared with 1 cm. Under waterlogged stress, seedling EP showed no significant differences between 1 and 3 cm for 50% of the 16 cultivars. Moreover, seedling EP was significantly improved at 3 cm after seed priming with GS compared with 1 cm, with increases of 46.4% (drought) and 63.0% (waterlogged), whereas no significant differences were observed under normal water conditions. Furthermore, plant phenotypic performance indices were higher at 3 cm with GS treatment than at 1 cm across all water conditions. DISCUSSION: Collectively, a sowing depth of 3 cm combined with exogenous application of GS not only promoted seedling emergence but also benefited subsequent plant growth in direct-sown rapeseed. These results provide practical insights for ensuring reliable seedling establishment in rapeseed.