盐碱胁迫对柳枝稷抗氧化及渗透调节的影响

Effects of salt alkali coupling stress on antioxidation and osmotic regulation of switchgrass

摘要:

柳枝稷(Panicum virgatum)可广泛应用于盐渍化地区的土壤改良。本试验以柳枝稷品种 Alamo(低地型)和 Blackwell-1(高地型)为材料，采用浓度为 60 mmol/L 的 Na₂CO₃溶液(盐胁迫)和 3 种不同碱度 NaOH 溶液即 pH 值分别为 7. 0(CK，无胁迫)、8. 0、9. 0 组合处理，探究盐碱不同胁迫时间对柳枝稷抗氧化及渗透调节的影响。结果表明：(1)盐碱胁迫下柳枝稷的光合色素含量均随胁迫时间的增加而下降，并在最后一次取样时显著下降(P＜0. 05)，柳枝稷光合色素的合成受到了影响。(2)盐碱胁迫下柳枝稷的相对水分含量、电导率和丙二醛(MDA)含量随胁迫时间的增加呈先上升后下降的趋势。(3)盐碱胁迫下柳枝稷的抗坏血酸过氧化物酶(APX)、过氧化氢酶(CAT)和过氧化物酶(POD)含量均有显著上升(P＜0. 05)，对柳枝稷维持正常生长起重要作用。(4)盐碱胁迫下柳枝稷可溶性蛋白含量上升但未见明显差异(P＞0. 05)，可溶性糖含量出现显著差异(P＜0. 05)。Alamo 的可溶性蛋白含量低于 Blackwell-1，但可溶性糖增加量高于 Blackwell-1。综上所述，柳枝稷在盐碱胁迫下膜透性、抗氧化酶及渗透物质含量都有所增加；仅在盐胁迫条件下，第 4 次取样时的 Alamo 叶绿素 b 含量、类胡萝卜素含量、相对水分含量、APX、可溶性蛋白含量高于第 1 次取样，Blackwell-1 的变化相反；仅在碱胁迫下，Alamo 更能维持较高的光合色素含量、相对水分含量，抗氧化酶及可溶性糖含量。以上研究表明， 柳枝稷具有一定的耐碱能力，Alamo 比 Blackwell-1 更耐盐碱的作用体现在氧化和渗透调节方面。

Abstract:

Switchgrass(Panicum virgatum)can be widely used for vegetation improvement in salinized areas. In this experiment，switchgrass Alamo(lowland type)and Blackwell-1(upland type)were used as materials to explore the effects of saline alkali stress on the antioxidant and osmotic regulation of switchgrass by using Na₂CO₃ solution (salt stress)with concentration of 60 mmol/L and three different alkalinity NaOH solutions，namely pH 7. 0(CK，no stress)，8. 0 and 9. 0. The results showed that：(1)Under saline alkali stress，the content of photosynthetic pigment of switchgrass decreased with the increase of stress time，and decreased significantly at the last sampling(P＜0. 05)， and the synthesis of photosynthetic pigment of switchgrass was affected.(2)The relative water content，electrical conductivity and malondialdehyde(MDA)content of switchgrass increased first and then decreased with the increase of stress time under saline alkali stress.(3)The contents of ascorbic acid peroxidase(APX)，catalase(CAT)and peroxidase(POD)of switchgrass increased significantly under saline alkali stress(P＜0. 05)，which played an impor- tant role in maintaining the normal growth of switchgrass.(4)Under saline alkali stress，the soluble protein content of switchgrass increased，but there was no significant difference(P＞0. 05)，and the soluble sugar content showed sig- nificant difference(P＜0. 05). The soluble protein content of Alamo was lower than that of Blackwell-1，but the in- crease of soluble sugar content was higher than that of Blackwell- 1，which may indicate that the change of soluble sugar content can reflect the salt and alkaline tolerance better. In conclusion，the membrane permeability，antioxidant enzyme and osmotic substance content of switchgrass increased under saline alkali stress. Only under salt stress condi- tions，the contents of chlorophyll b，carotenoid，relative water content，APX and soluble protein in Alamo at the fourth sampling were higher than those at the first sampling，while the changes of Blackwell-1 were opposite. Only under al- kali stress，Alamo could maintain higher photosynthetic pigment content，relative water content，antioxidant enzyme and soluble sugar content. These results indicated that the switchgrass species Alamo and Blackwell-1 had certain sa- line-alkali tolerance，and Alamo was more salt tolerant than Blackwell-1 in antioxidant and osmotic regulation.