外源水杨酸缓解金花菜高温胁迫的生理响应

Physiological effects of exogenous salicylic acid on relative high temperature stress in Medicago polymorpha

金花菜(Medicago polymorpha)在长江流域及以南地区广泛种植,在夏季高温时普遍处于逆境状态,调节或缓解其高温胁迫效应尤为关键。采取盆栽栽培模式,分析对比无胁迫条件下和高温逆境下不同浓度(0、0.5、1.0、1.5、2.0、2.5 mmol·L^(-1))水杨酸(SA)处理后金花菜的生长及生理指标,探究SA对高温胁迫的缓解效应。结果表明:高温胁迫下金花菜生长速率受到明显抑制,叶绿素含量和OJIP荧光瞬态曲线显著下降。施加不同浓度的SA处理后,金花菜地上和地下生物量、可溶性蛋白质和可溶性糖含量、CAT和POD活性、叶绿素参数Fm均显著提高,丙二醛含量和相对电导率显著降低,其中2.5 mmol·L^(-1)SA处理对高温胁迫下金花菜的生长促进作用最为显著。综合而言,外源SA能通过提高叶绿素含量和POD活性等方式有效缓解高温胁迫对金花菜的生理影响。

Medicago polymorpha is widely planted in the Yangtze River Basin and south of it. It is generally in a state of adversity during high summer temperature, and it is particularly critical to regulate or alleviate the high temperature stress. A pot culture was adopted in this study. The growth and physiological indices of M.polymorpha were analyzed by adding salicylic acid(SA) at different concentrations(0, 0.5, 1.0, 1.5, 2.0, 2.5 mmol·L^(-1)) under high temperature adversity and compared with untreatment condition, aiming to study the mitigation effect of SA on high temperature stress. The results showed that the growth rate of M.polymorpha was significantly inhibited, and chlorophyll content and OJIP fluorescence transient curve decreased significantly under high temperature stress. The addition of different concentrations of SA could significantly increase above-ground and underground biomass, soluble protein and soluble sugar content, CAT and POD activities and chlorophyll parameter Fm value, but significantly decreased MDA content and relative conductivity. Notably, the 2.5 mmol·L^(-1)SA had the most significant effect on the growth of M.polymorpha. In summary, the addition of exogenous SA could effectively mitigate the physiological effects of high temperature on M.polymorpha by increasing chlorophyll content, POD activity and etc.