中文摘要：

低温是影响东北地区玉米生长发育的主要因素之一。5-氨基乙酰丙酸（ALA）具有增强作物抗逆性的作用,近年来成为国内外的研究重点。为了探究ALA缓解玉米幼苗低温胁迫的生理机制及叶面喷施的最适浓度,选取＂绥玉13号＂为试验材料,叶面喷施不同浓度的ALA（0、10、20、30和40 mg·L^-1）,在昼/夜温度为14℃/5℃的低温条件下培养48h,研究ALA对玉米幼苗生长、细胞膜稳定性、抗氧化酶活性及渗透调节物质的影响。结果表明：叶面喷施ALA能促进低温胁迫下幼苗生长,保护叶片细胞膜的结构与功能,增强细胞清除活性氧能力,提高渗透调节的能力;其中以喷施20 mg·L^-1ALA效果最佳,与对照相比均达到显著水平（P〈0.05）,幼苗株高、叶面积和鲜（干）重分别增加24%、23%和26%（24%）,MDA含量和相对电导率减少38%和45%,SOD和POD活性增加37%和66%,可溶性蛋白和可溶性糖含量增加50%和45%;叶面喷施适宜浓度的ALA可以缓解低温胁迫对玉米幼苗的损伤。

英文摘要：

Low temperature is one of the major factors which produce adverse effects on maize growth and development in Northeast China. 5-aminolevulinic acid （ALA） can improve the low temperature resistance of crops. The objective of this study was to investigate the physiological mechanism of ALAenhanced lowtemperature resistance in maize seedlings as well as the optimal foliar spraying concentration of ALA. This experiment was conducted with maize cultivar ‘Suiyu 13’ under different concentrations of ALA （0, 10, 20, 30, 40 mg·L^-1）, at low temperature of 14 ℃/5 ℃ （day/night） for 48 h. Plant morphological growth, cell membrane stability, antioxidant enzyme activity and osmotic adjustment ability were measured. The results showed that foliar spraying of ALA could promote the growth of seedlings under low temperature stress, protect the structure and function of leaf cell membrane, enhance the ability of the cell to remove reactive oxygen species and improve the ability of osmotic adjustment. Among all treatment concentrations, 20 mg·L^-1 ALA spraying treatment had the best effects. Compared with the control, seedling height, leaf area and fresh （dry） weight increased by 24%, 23%, 26% （23%）, the malondialdehyde （MDA） content and relative electrical conductivity decreased by 38% and 45%, SOD activity and POD activity increased by 37% and 66%, soluble protein content and soluble sugar content increased by 50% and 45%, respectively, under the treatment of 20 mg·L^-1 ALA. Therefore, spraying ALA of appropriate concentration can relieve the damage caused by low temperature stress to maize seedlings.