不同品种玉米在盐碱复合胁迫下的幼苗生长差异及其生理机制

Seedling growth difference and physiological mechanism of different maize cultivars under mixed salinealkali stress.

为探明玉米的耐盐碱机制,推动耐盐碱玉米品种的选育,以“郑单958”和“ZN451”为试验材料,用25 mmol·L^(-1)Na_(2)CO_(3)和100 mmol·L^(-1)NaCl对幼苗进行盐碱复合胁迫处理,探究盐碱复合胁迫对玉米幼苗生长及生理指标的影响。结果表明:处理组“郑单958”的株高、地上干重、单株总干重均极显著低于其对照组,根冠比高于对照组但差异不显著;脯氨酸含量显著高于对照组,可溶性蛋白含量比对照组低但降幅不显著;MDA含量显著高于对照组,SOD活性极显著高于对照组,POD活性显著低于对照组;SPAD值显著低于对照组,Gs、Ci、Pn、Fv/Fm、PI值均极显著低于对照组;ABA、JA含量均极显著高于对照组;处理组“ZN451”的株高、地上干重均显著低于其对照组,单株总干重低于对照组但降幅不显著,根冠比极显著高于对照组;脯氨酸、可溶性蛋白含量均显著高于对照组;MDA含量显著高于对照组但差异不显著,SOD活性极显著高于对照组,POD活性显著高于对照组;SPAD值、Pn、Fv/Fm、PI值均低于对照组但差异不显著,Gs、Ci值均显著低于对照组;ABA、JA含量均极显著高于对照组。本研究表明,玉米品种“ZN451”在盐碱复合胁迫中可能有较强的生物量分配的调控机制,高活性的抗氧化酶系统保证了细胞膜的完整性,提高了细胞渗透压的调控能力,进而对酶活性和光合系统有了较好的保护;尽管盐碱逆境中“ZN451”的气孔导度下降,但相关系统的结构和功能并未受到损伤,因此具有较高的盐碱抗逆能力。

To explore the mechanism underlying the saline-alkali tolerance of maize and promote the breeding of saline-alkali tolerant cultivars,the seedlings of maize cultivars“Zhengdan 958”and“ZN451”were subjected to saline-alkali stress with 25 mmol·L^(-1 )Na_(2)CO_(3)and 100 mmol·L^(-1 )NaCl.We investigated the effects of saline-alkali stress on the growth and physiological characteristics of maize seedlings.The results showed that plant height,aboveground dry weight and total dry weight per individual of“Zhengdan 958”under saline-alkali stress were significantly lower than those in control.The root-shoot ratio under saline-alkali stress was higher than that of control group,but the difference was not statistically significant.The proline content in treatment group was significantly higher than that of control,while soluble protein was lower but the reduction was not significant.The MDA content and the SOD activity in treatment group were significantly higher than the control.POD activity and SPAD readings were significantly lower than those of the control.Gs,Ci,Pn,Fv/Fm,and PI values were all significantly lower than those in the control.The contents of ABA and JA were significantly higher than those in the control.Plant height and aboveground dry weight of“ZN451”in the treatment group were significantly lower than those in the control.The dry weight of individual plant was higher than that of control group,but the difference was not significant.The root-shoot ratio was significantly higher than that of control group.The contents of proline and soluble pro-tein were significantly higher than those of the control group.The MDA content was higher than that in the control,but the increase was not significant.SOD and POD activities in the treated group were significantly higher than that in the control.The SPAD,Pn,Fv/Fm,and PI values were all slightly lower than those in the control.The Gs and Ci values were significantly lower than those in the control.The contents of ABA and JA were significantly higher than those in the control.Our results suggest that cultivar“ZN451”may have a strong regulatory mechanism for biomass allocation under saline-alkali stress.The high activity of antioxidant enzyme system of“ZN451”ensures the integrity of cell membrane,improves the cellular ability of osmoregulation,and thus provides better protection for antioxidant enzyme activity and photosynthetic system.Although the stomatal conductance of“ZN451”is reduced under saline-alkali stress,the structure and function of the relevant systems are not damaged.Therefore,cultivar“ZN451”has high salt-alkali resistance.