Seed priming with gibberellic acid and melatonin in rapeseed: Consequences for improving yield and seed quality under drought and non-stress conditions

The scarcity of water affects plant performance, yield and quality in many habitats and agriculture. Additionally, the survival of drought stress depends on the intensity and duration of the drought period. Seed priming improves the production and quality of crops under normal and unfavorable environmental conditions, perhaps linked with invoking stress memory. Pot and field experiments were conducted to investigate whether seed priming could improve rapeseed yield and quality under drought-stress and non-stress conditions. We primed the seeds of two rapeseed cultivars viz., Shenguang 127 (SG 127) and Huayouza 9 (HZ 9) with gibberellic acid (GA(3)) and melatonin (MT). The potted plants were subjected to severe drought stress of 35-40% FC at the flowering stage in well-controlled glasshouse conditions while in the field; the plants were grown under the open field conditions. In the pot experiment, a significant reduction in morphological traits; yield and yield components, and deterioration in seed qualitative attributes was recorded under the drought stress in both cultivars. However, the GA(3) and MT-primed plants exhibited less reduction in morphological traits, yield and yield components; and deterioration in seed qualitative attributes under the drought stress compared to no-primed plants. The results of our study reveal that the better performance of primed-issued plants was associated with better scavenging of reactive oxygen species (ROS) through the activation of antioxidant enzymes and more accumulation of proline as compared to no-primed plants both under normal and drought stress conditions. Nonetheless, GA(3) and MT-priming also improved the morphological traits, seed yield, and seed qualitative attributes under the open field conditions compared to no-primed treatment. Taking together, the finding of our study may explore new avenues and advancing priming-induced drought tolerance helping to improve rapeseed productivity and quality under water scarcity and semi-arid cropping system.