土壤水分胁迫对红砂幼苗叶绿素荧光和抗氧化酶活性的影响

以红砂(Reaumuria soongorica)2年生幼苗为材料,研究不同土壤水分处理下其叶绿素荧光参数、叶绿素含量和抗氧化酶活性等光合生理指标的变化特征。取得如下结果。(1)与对照组(CK)相比,中度胁迫(MS)和重度胁迫(SS)处理下红砂叶绿素含量分别降低了15.3%和25.7%,叶绿素(a/b)含量分别增加了7.4%和36.9%。表明胁迫处理导致色素含量和捕光色素复合体II含量下降,减少了其对光能的捕获,降低了光合机构遭受破坏的风险。(2)随着胁迫的加剧,初始荧光(Fo)呈升高趋势,而最大荧光(Fm)、PSII潜在光化学效率(Fv/Fo)和PSII最大光化学效率(Fv/Fm)呈明显降低趋势。说明胁迫使PSII结构与功能受到一定程度的损伤和破坏。(3)在胁迫处理下,抗氧化酶活性和丙二醛含量也发生了一定程度的变化,反映出红砂对胁迫环境有较强的耐受性。

Effect of Soil Water Stress on Chlorophyll Fluorescence and Antioxidant Enzyme Activity in Reaumuria soongorica Seedlings

We investigated the effect of different soil water stress on chlorophyll fluorescence variables, chlorophyll content and antioxidant enzyme activities in 2-year-old Reaumuria soongorica seedlings. Chlorophyll content significantly decreased with increasing soil water stress. Compared with the control, under medium water stress and severe water stress, chlorophyll content decreased by 15.3% and 25.7%, respectively; and Chl a and Chl b increased by 7.4% and 36.9%, respectively. Thus, under soil water stress conditions, the chlorophyll content and the content of Chl （a/b） binding proteins （LHCll） decreased, the capture of leaf to light energy was reduced, and the risk of photosynthetic apparatus damage was reduced. Fo increased with increasing soil water stress, however Frn, Fv/Fo and FvlFrn decreased. Thus, soil water stress could cause a certain degree of damage or fracture to its PSII reaction center. Soil water stress produced some changes in antioxidant enzyme activity and malondialdehyde （MDA） content, so R. soongorica shows good tolerance to soil water stress.