Morpho-physiological and biochemical responses of tolerant and sensitive rapeseed cultivars to drought stress during early seedling growth stage

The edible oil production in China is highly dependent on the screening and development of drought-resistant rapeseed cultivars especially in water stress areas. However, for the successful production of rapeseed, germination and early seedling growth is the key steps under drought stress, which are not fully understood up till now. To better predict about the adoption of rapeseed cultivars to drought stress, the current study explored the presumed roles of enzymatic, non-enzymatic antioxidants and osmolytes in improving drought tolerance in rapeseed. The comparative analysis in terms of germination and early sprouting growth of six rapeseed cultivars was assessed under normal (0.00 MPa) and osmotic stresses (− 0.1, − 0.2, − 0.3, − 0.4, and − 0.5 MPa simulated by polyethylene glycol 6000). Subsequently, based on the process of germination and early sprouting growth, Shenguang 127 (SG 127) and Zhongyou 36 (ZY 36) were chosen as drought-tolerant and -sensitive rapeseed varieties, correspondingly and further evaluated under − 0.3 MPa osmotic stresses. The results indicated that drought stress rigorously hindered germination and early seedling growth of rapeseed cultivars. On the other hand, SG 127 exhibited less reduction in seedling growth paralleled with ZY 36. SG 127 revealed lower levels of hydrogen peroxide (H2O2), lipids peroxidation (MDA), electrolyte leakage (EL %) and less reduction in chlorophyll (Chl) content than ZY 36. The drought tolerance of SG 127 may be correlated with enhanced activities of enzymatic (superoxide peroxidase, catalase, and dismutase), non-enzymatic antioxidants (ascorbic acid, glutathione), more accumulation of proline; total soluble sugar and total soluble protein. Furthermore, our study highlighted the significance of enzymatic and non-enzymatic antioxidants and osmolytes in the establishment of rapeseed seedlings under drought stress. Nevertheless, the better knowledge is crucial to be further investigated on genomic and molecular basis to deeply insight the detail mechanisms of drought tolerance in rapeseed.