沙尘胁迫对山楂光合、荧光特性的影响

Effects of dust stress on photosynthetic and chlorophyll fluorescence characteristics of Crataegus spp.

以23a生山楂为试验材料,对叶片进行轻度沙尘胁迫(5mg/cm^2)和重度沙尘胁迫(12mg/cm^2),无沙尘覆盖为对照,并在10d、20d、30d、40d时测定叶片的光合、叶绿素荧光等参数,为山楂栽培管理提供理论依据。结果表明:随着沙尘胁迫程度的加重,山楂的净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)呈下降趋势,重度沙尘胁迫的下降幅度大于轻度沙尘胁迫;但胞间CO_2浓度(Ci)呈先升后降的变化趋势,轻度沙尘胁迫的Ci值始终大于重度沙尘胁迫,说明在沙尘胁迫处理前期,非气孔因素是限制山楂叶片光合作用的主要因素,到处理后期气孔因素成为主要限制因素。沙尘胁迫导致最大PSⅡ量子产率(QYmax)呈下降趋势,但在处理后期通过提高PSⅡ的潜在活性(Fv/F0)、稳态下非光化学淬灭系数(q N_Lss)和稳态下PSⅡ的光淬灭系数(q P_Lss)来消耗过剩光能,保护光合机构。

The research focused on Crataegus spp.,the stress treatment was performed by mild dust stress(5 mg/cm^2)and sever dust stress(12 mg/cm^2),with 0 mg/cm^2 as a control.Photosynthesis and chlorophyll fluorescence parameters were measured at 10,20,30 and 40 d after treatment.The result showed that with the dust stress increasing,Pn,Gs and Tr decreased;Ci increased at the beginning but later declined,and that under severe dust treatment was more than that under mild dust treatment,showing that non-stomatal restrictions to the photosynthetic rate was the main factor at the beginning of the treatment,but stomatal inhibition became the main factor at later stages.Dust stress reduced QYmax,but the plant protected the photosynthetic mechanism by increasing Fv/F0,qN_Lss and qP_Lss to consume excess luminous energy.