Effects of Gibberellin Pre-Treatment on Seed Germination and Seedling Physiology Characteristics in Industrial Hemp under Drought Stress Condition

The present study aimed to explore the effects of exogenous gibberellins (GAs) on seed germination and subsequent seedling growth of hemp (Cannabis sativa L.) under drought stress. Seeds of two industrial hemp cultivars i.e., 'Yunma 1', (YM) and 'Bamahuoma', (BM) were treated with different concentrations of GA(3) solution (0, 200, 400, 600, 800 mg/L) at 20 degrees C for 8 h. The effect of pre-treatment was assessed on germination characteristics and physiological indexes on subsequent exposure to drought stress using 20% (m/v) polyethylene glycol (PEG) for 7 days. The results revealed that seed germination in hemp was sensitive to drought stress, as the germination indexes (germination rate and germination potential) decreased significantly, and seedling growth (hypocotyl length and radicle length) was impeded under 20% PEG-6000 condition. GA(3) pre-treatment affected germination rate, germination potential, hypocotyl length and radicle length. With increasing GA(3) concentration, these indexes first increased and then decreased. For seedling physiology characteristics in hemp, GA(3)-pretreatment remarkedly increased the osmotic regulating substances (soluble sugar and soluble protein contents) and the activities of antioxidant enzymes (SOD, superoxide dismutase and POD, peroxidase), while sharply decreased the lipid peroxidation (malondialdehyde, MDA) in seedlings grown under PEG-6000 induced drought stress. These results suggested that seeds pre-treated with GA(3) could enhance the drought tolerance of hempseeds, and the optimal effect of GA(3) for seed pre-treatment of YM and BM could be obtained when the concentration of GA(3) solution reached 400 mg/L and 600 mg/L, respectively.

Automated summary

The present study investigated the effects of exogenous gibberellins on seed germination and subsequent seedling growth of hemp under drought stress. The results showed that pre-treatment with GA(3) can enhance the drought tolerance of hempseeds, and the optimal effect of GA(3) for seed pre-treatment was achieved at concentrations of 400 mg/L and 600 mg/L for YM and BM cultivars, respectively.