温度胁迫对柱花草叶绿素荧光参数和光合速率的影响

为了探讨柱花草对不同温度的适应机制,以播种后40 d的幼苗为试验材料,在光照培养箱内分别用高温(36℃)处理5 d,低温(6℃)处理2 d,并以常温(25℃)处理5 d为对照,测定光合速率及叶绿素荧光参数等相关指标在不同温度胁迫下的变化。结果表明,低温处理2 d,叶绿素荧光参数的最大光化学效率(Fv/Fm)、光系统Ⅱ电子传递量子效率(Ф_PSⅡ)、光化学猝灭系数(qP) 和非光化学猝灭系数(NPQ)、叶片光合速率、叶片ATP含量及RuBPcase和FBPase活性显著降低;而高温处理5 d对其光合效率没有产生明显的抑制作用。在温度胁迫条件下,足够的ATP供应对保证柱花草的光合能力是有必要的。

Effects of temperature stress on chlorophyll fluorescence parameters and photosynthetic rates of Stylosanthes guianensis

In order to explore the adaptation mechanisms of Stylosanthes guianensis to temperature stress,the responses of Chlorophyll fluorescence parameters and photosynthetic rates in leaves under low and high temperature stresses were studied.40 days old seedlings were divided into three groups and transferred to growth chambers with different temperature treatments.The first group was subjected to temperature at 6℃ for 2 days as low temperature stress,the second group at 36℃ for 5 days as high temperature stress,and the third group at 25℃ for 5 days as the control.The experimental results showed that the chlorophyll fluorescence parameters(Fv/Fm,ФPSⅡ,qP) and photosynthetic rates in the leaves of S.guianensis decreased significantly as treated with cold stress,and were not affected under heat stress,which indicates that photosystem Ⅱ activity in S.guianensis was more sensitive to cold stress than heat stress.In addition,ATP content and activities of RuBPcase and FBPase in the leaves of S.guianensis were also decreased under cold stress,but it was not affected under heat stress.Therefore,sufficient ATP content in leaves perhaps can prevent decreasing photosynthetic rate in S.guianensis leaves.