不同盐胁迫下小麦叶片渗透性调节和叶绿素荧光特性

盐胁迫对植物伤害机理受到普遍关注。本试验以‘西旱3号’小麦幼苗为材料,通过比较钠盐(150 mmol·L^-1)、钙盐(5、30 mmol·L^-1)单独及其复合胁迫对叶片渗透调节和光合特性的影响,揭示不同盐胁迫对小麦的伤害机理。结果表明: 钠盐或钙盐单独胁迫显著抑制了小麦幼苗根、茎的生长,使叶片可溶性糖和脯氨酸含量、调节性能量耗散电子产量、非光化学猝灭及玉米黄质相对含量均显著增加,而叶绿素a和叶绿素b含量、最大光化学效率、PSⅡ实际光化学效率、光化学猝灭及光合电子传递效率均显著下降。此外,钙盐对小麦幼苗生长的抑制作用更强,钠盐处理下叶片叶绿素含量减少和叶绿素荧光参数降低更显著。除了可溶性蛋白、叶黄素和玉米黄质相对含量以外,低浓度钙盐有效缓解了钠盐诱导其他各指标的变化,而高浓度钙盐进一步增大了钠盐处理小麦幼苗各参数的变化幅度。总之,钠盐和钙盐显著抑制了小麦幼苗的生长,低浓度钙盐能有效缓解钠盐对小麦幼苗的伤害,而高浓度钙盐加剧了钠盐的毒害作用。这均与叶片光合色素含量、光能捕获及光合电子传递的改变有关。此外,渗透调节物质在增强钠盐或钙盐环境中小麦幼苗的抗性方面发挥着重要作用。

Osmotic regulation and chlorophyll fluorescence characteristics in leaves of wheat seedlings under different salt stresses

The damage mechanism of salt stress on plants has attracted much attention. In order to reveal the damage mechanism of different salt stresses, we compared osmotic regulation and photosynthetic characteristics of seedlings of wheat cultivar Xianhan 3 under sodium salt (150 mmol·L^-1) and calcium salt (5, 30 mmol·L^-1) treatments alone or in combination. The results showed that sodium salt or calcium salt stress alone significantly inhibited the growth of roots and stems, but increased the amount of soluble sugar and proline, regulatory energy-dissipated electron yield, non-photochemical quenching and relative content of zeaxanthin contents in leaves. In contrast, salt treatments alone significantly decreased the levels of chlorophyll a and chlorophyll b, maximum photochemical efficiency, PSⅡ photochemical efficiency, photochemical quenching and photosynthetic electron transport efficiency. Furthermore, the inhibition of wheat seedling growth was more sensitive to calcium salt than to sodium salt stress, whereas the decreases of chlorophyll content and chlorophyll fluorescence parameters were more prominent in response to sodium salt stress. Except for the amount of soluble protein, lutein and the relative level of zeaxanthin, the changes of other parameters in the leaves due to sodium salt stress were effectively blocked by the application of low calcium concentration, but further increased by the presence of high calcium salt concentration. Taken together, sodium or calcium salt stress alone significantly inhibited seedling growth. The toxicity of sodium salt to wheat seedlings was effectively alleviated by low calcium concentration, but was aggravated by high calcium concentration, which were associated with the changes of photosynthetic pigment content, light energy capture, and photosynthetic electron transport process in the leaves of wheat seedlings. Moreover, osmotic regulators played an important role in enhancing the resistance of wheat seedlings to sodium or/and calcium environment.