Physiological effects of different exogenous substances spraying on seedlings of 'Yunma 1' under drought stress

In order to explore the effects of different exogenous substances on the seedling stage of industrial hemp under drought stress, ‘Yunma 1’ was used as experimental material. Drought stress was simulated by pot water control method. The physiological responses of Vc, betaine, CaCl₂ and gibberellin spraying treatments with different concentrations (200, 500, 800 and 1 200 mg/L) to drought resistance of industrial hemp seedlings were studied. The results showed that drought stress reduced the contents of chlorophyll, proline and soluble sugar, and the activities of SOD and POD in ‘Yunma 1’ seedlings compared with the control. Exogenous substances such as Vc, betaine, CaCl₂ and gibberellin could increase the contents of chlorophyll, proline and soluble sugar in seedlings, as well as the activities of SOD and POD, thus alleviating the damage of drought stress to seedlings to a certain extent. According to the evaluation result of membership function, ‘Yunma 1’ had better physiological drought resistance when being sprayed 500 mg/L Vc and CaCl₂ respectively, and had better mitigation effect being sprayed with 200 mg/L betaine and gibberellin. The alleviating effects of four exogenous substances were Vc > CaCl₂ > Gibberellin > Betaine. The results reveal the physiological response of hemp seedlings to exogenous substances spraying under drought stress, and provide a reference for improving drought resistance of industrial hemp by exogenous substance treatment.