水分胁迫对春播玉米苗期生长及其生理生化特性的影响

采用盆栽试验,以‘蠡玉18'玉米单交种为供试材料,设置充分供水(CK)、轻度水分胁迫(LS)、中度水分胁迫(MS)和重度水分胁迫(SS)4个水分处理水平,研究了水分胁迫对春播玉米苗期保护酶活性和生长的影响,以探讨土壤水分胁迫对玉米苗期生长发育及其生理过程的影响机制.结果表明:(1)随着水分胁迫程度的加剧,玉米幼苗的生物量显著下降,根冠比、根系活力和脯氨酸含量增加,且水分胁迫对玉米幼苗地上部生物量的抑制作用更大；可溶性蛋白含量差异不明显,MDA含量波动变化.(2)随着水分胁迫时间的延长,根冠比、根系活力和植株脯氨酸含量先升高后降低,可溶性蛋白含量呈先下降后升高的趋势；玉米幼苗叶片和根系MDA积累波动变化,而叶片MDA含量始终高于根系.(3)在水分胁迫初期,玉米叶片中CAT活性较SOD、POD响应更敏感；玉米苗期根系在中度水分胁迫下主要依赖CAT来降低氧化危害,而在重度水分胁迫下前期主要依赖CAT、后期通过CAT和POD的共同作用来降低氧化伤害；水分胁迫条件下,叶片和根系POD同步降低氧化伤害,而SOD和CAT在叶片和根系间存在互补作用.研究表明,在不同程度的水分胁迫条件下,玉米幼苗的生长受到一定程度的抑制,但其能够通过调节自身的保护酶活性和渗透调节物质含量来减轻干旱伤害,维持植株的正常生理代谢功能.

Effects of Physiological and Biochemical Characteristics and Growth under Water Stress in Seedling of Spring Maize

To study the effects of physiological and biochemical characteristics and growth under water stress,we potted Liyu 18 seedlings under four different soil content levels:optimal water content (CK),mild water stress (LS),moderate water stress (MS) and severe water stress (SS),which were controlled by weighing the soil and pots.The results showed that:(1)With the increase of stress level,the maize biomass was significantly reduced,while root shoot ratio,root activity,proline content were increased.The influence of water stress on above-ground part was more than that of root.Soluble protein content was not significantly different and MDA content fluctuated.(2)Along with the period of water stress continued,root shoot ratio,root activity and proline content were increased and then decreased;soluble protein of roots was declined and then increased.MDA accumulation fluctuated in seedling of maize and MDA content in leaf were higher than that in root.(3)In preliminary stress,CAT was more sensitive than SOD and POD in leaf;root in moderate water stress mainly depends on CAT to reduce oxidation damage,while it also depends on CAT in severe water stress early and then through the CAT and POD common action to reduce the oxidation damage.POD synchronously reduced oxidation damage in leaf and root,while the complementary role existed between SOD and CAT in leaf and root.We can conclude that the growth of maize seedlings were negatively influenced by different degree of drought stress,but the protective enzyme system and osmatic adjustment substance could adjust themselves to avoid water drought harms.