土壤水分对柿树光合光响应特性的影响

Effects of soil moisture on characteristics of photosynthesis response to light of Diospyros Kaki

采用CIRAS-2便携式光合仪测定不同土壤水分条件下2年生柿树叶片净光合速率、蒸腾速率、水分利用效率、气孔导度等光合生理参数的光响应过程,探讨柿树光合光响应特性对土壤水分的响应规律。结果表明:土壤水分对柿树的光合生理参数影响显著,随着土壤水分的降低,净光合速率、表观量子效率先升后降,光补偿点先降后升,光饱和点呈下降趋势;维持柿树高光合作用和高水分利用效率的适宜土壤相对含水量为48.8%～76.7%,适宜的光照强度为800～2 000μmol/(m2·s);柿树对强光利用能力较强,而对弱光的利用效率较低;在土壤相对含水量为48.8%时,柿树光合作用主要受气孔限制,而土壤相对含水量降低到25.5%时,柿树光合作用转变为非气孔限制,通过对气孔、非气孔因素的判定,可知柿树是一种抗旱性非常强的植物。研究结果可为柿树的节水高产栽培提供理论依据。

We measured the light response of photosynthetic physiology parameters by CIRAS-2 portable photosynthesis system,such as net photosynthetic rate,transpiration rate,water use efficiency and stomatal conductance,in two-year-old Diospyros Kaki under different soil water conditions.The light response rule of Diospyros Kaki was studied under series of soil moisture.The results show that soil water content had significant effects on the photosynthetic parameters of Diospyros Kaki.With the decreasing soil moisture,net photosynthetic rate and apparent quantum yield increased first,and then decreased.Meanwhile light compensation point decreased first,and then increased.Light saturation point represented a decreasing tendency.Higher net photosynthetic rate and water use efficiency were observed when the relative soil water contents（Rwc） were from 48.8% to 76.7% and the photosynthetic active radiation were from 800 to 2 000 μmol/（m2·s）.Diospyros Kaki had the higher ability to utilize strong light,but lower to utilize weak light.When Rwc was 48.8%,the main reason of photosynthesis declination was stomatal limitation.As Rwc was 25.5%,the declination was changed from stomatal limitation turned to non-stomatal limitation.Judging from stomatal factor and non stomatal factor,we can get the conclusion that the drought resistance of Diospyros Kaki is very strong.The results in this study could provide theory for water saving activity and high yield cultivation of Diospyros Kaki.