外源5-ALA对干旱胁迫下玉米种子萌发及幼苗生长的影响

干旱是影响西北地区玉米生长发育的主要因素之一,5-氨基乙酰丙酸（5-ALA）是一种潜在的生理活性物质,具有增强植物抗逆性的作用。为了探明干旱胁迫下5-ALA对玉米种子萌发和幼苗生长的缓解效应,同时筛选出缓解的最佳浓度,以玉米品种“郑单958”为材料,以蒸馏水为对照,研究20% PEG 6000模拟干旱胁迫下不同浓度5-ALA（0、5、10、15、20、25、30mg/L）对玉米种子萌发及幼苗生长的影响。结果表明,与对照相比,干旱胁迫下玉米种子的萌发和幼苗生长受到明显抑制,幼苗的渗透调节物质含量减少,抗氧化酶活性降低,丙二醛（MDA）含量增加,质膜透性增大。与0mg/L 5-ALA处理相比,一定浓度（25mg/L）的5-ALA能明显缓解干旱胁迫对玉米幼苗造成的伤害,玉米幼苗的主根长、芽长、根鲜重、芽鲜重、根干重和芽干重显著增加,种子发芽势和发芽率显著提高了76.92%和65.52%,脯氨酸、可溶性糖和可溶性蛋白含量分别上升了136.82%、81.36%和121.26%,超氧化物歧化酶、过氧化物酶和过氧化氢酶活性分别增加了200.58%、182.10%和536.56%。MDA含量和细胞质膜透性则分别下降64.54%和68.21%。5-ALA的缓解作用具有明显的剂量效应,其中以浓度25mg/L处理效果最好。

Effects of Exogenous 5-Aminolevulinic Acid on Seed Germination and Seedling Growth of Maize under Drought Stress

Drought is one of the major variables affecting maize development and growth in Northwest China. 5-aminolevulinic acid (5-ALA) is a possible physiological active chemical substance that can help plants withstand stress. The effects of 5-ALA at different concentrations (0, 5, 10, 15, 20, 25, 30mg/L) on the germination and seedling growth of 20% PEG 6000 under drought stress were studied in order to clarify the effect of 5-ALA on maize germination and seedling growth under drought stress and to select the best concentration of the treatment, with the water as control. The results showed that, compared with the control, the germination and seedling growth of maize seeds were significantly inhibited under drought stress, the content of osmoregulation substances decreased, the activities of antioxidant enzymes decreased, the content of malondialdehyde (MDA) increased, and the permeability of plasma membrane increased. Compared with 0mg/L 5-ALA treatment, the treatment with 25mg/L 5-ALA could alleviate the damage caused by drought stress to maize seedlings, the main root length, bud length, root fresh weight, bud fresh weight, root dry weight and bud dry weight of maize seedlings were significantly increased, seed germination potential and germination rate were significantly increased by 76.92% and 65.52%, and the contents of proline, soluble sugar and soluble protein were increased by 136.82%, 81.36%, and 121.26%, respectively. The activities of superoxide dismutase, peroxidase and catalase increased by 200.58%, 182.10% and 536.56%, respectively. MDA content and cytoplasmic membrane permeability decreased by 64.54% and 68.21%, respectively. The dose effects of 5-ALA was obvious, and the treatment with 25mg/L 5-ALA was the best.