Abstract: In order to explore the exogenous spermine (Spd) of sweet sorghum seedling growth under drought stress and the influence of the physiological and biochemical indicators, taking the sweet sorghum varieties Liaotian 1 as material under the indoor potted condition, this paper studied the effects of exogenous Spd on growth, photosynthesis, organic osmotic regulators and antioxidant protective enzymes of sweet sorghum seedlings under drought stress at three different concentration (0.6、1.2、1.8 mmol·L-1) of the Spd spraying processing in drought stress (15% PEG6000 simulation) of sweet sorghum seedling. The results showed that: Drought stress could significantly inhibit the growth and the physiological and biochemical indexes changes of sweet sorghum seedlings, while the spraying of Spd at different concentrations could improve the growth, photosynthetic efficiency, organic osmotic regulatory substance content and antioxidant protective enzyme activity of sweet sorghum seedlings under drought stress. Compared with drought stress treatment, the plant height of sweet sorghum seedlings sprayed with 1.2 mmol·L-1 Spd for 15 d increased by 31.62%, fresh weight increased by 58.29%, dry weight increased by 49.53%, leaf area increased by 30.96%, net photosynthetic rate increased by 135.40%, stomatal conductance (Gs) increased by 138.60%, transpiration rate increased by 158.54%, proline content increased by 71.16%, malondialdehyde content decreased by 53.17%, and superoxide dismutase activity increased by 39.69% under drought stress. This result indicated that under drought stress, the specific concentration (1.2 mmol·L-1) of exogenous Spd was beneficial to alleviate drought stress on sweet sorghum growth inhibition, increase the chlorophyll content of sweet sorghum seedling under drought stress and antioxidant enzyme activity, reduce the level of membrane lipid peroxidation, so as to relieve the drought stress to the injury of the sweet sorghum, sweet sorghum seedling drought resistance.

Key words: sweet sorghum, drought stress, spermidine, seedling growth, physiology and biochemistry

摘要： 为探究外源亚精胺（spermidine，Spd）对干旱胁迫下甜高粱幼苗生长及生理生化指标的影响，以甜高粱品种辽甜1号为试验材料，室内盆栽条件下，采用不同浓度（0.6、1.2、1.8 mmol·L-1）的Spd喷施处理干旱胁迫（15% PEG6000模拟）下的甜高粱幼苗，研究了外源Spd处理对干旱胁迫下甜高粱幼苗生长、光合作用、有机渗透调节物质和抗氧化保护酶的变化。结果表明：干旱胁迫能显著抑制甜高粱幼苗的生长及生理生化指标的变化，而喷施不同浓度Spd可提高干旱胁迫下甜高粱幼苗叶片甜高粱幼苗生长、光合效率、有机渗透调节物质含量和抗氧化保护酶活性。与干旱胁迫处理相比，叶面喷施1.2 mmol·L-1 Spd 15 d后，甜高粱幼苗株高提高31.62%，鲜重提高58.29%，干重提高49.53%，叶面积提高30.96%，净光合速率提高135.40%，气孔导度提高138.60%，蒸腾速率提高158.54%，脯氨酸含量提高71.16%，丙二醛含量降低53.17%，超氧化物歧化酶活性提高39.69%。说明在干旱胁迫下，特定浓度（1.2 mmol·L-1）的外源Spd有利于缓解干旱胁迫对甜高粱生长的抑制作用，提高干旱胁迫下甜高粱幼苗的叶绿素含量和抗氧化物酶活性，降低膜脂过氧化程度，从而缓解了干旱胁迫对甜高粱的伤害，增强甜高粱幼苗的耐旱性。

关键词: 甜高粱, 干旱胁迫, 亚精胺, 幼苗生长, 生理生化