蓄水坑灌条件下不同灌水下限幼龄苹果树叶片光合特性研究

以3a生矮砧红富士为试验材料,采用LI-6400XT便携式光合仪,对蓄水坑灌条件下不同灌水下限(分别为田间持水率的50%、60%、70%)幼龄苹果树叶片光合特性进行研究,并通过通径分析与多元逐步回归分析量化各影响因子与净光合速率的关系。结果表明:蓄水坑灌条件下不同灌水下限叶片净光合速率、气孔导度、蒸腾速率、胞间CO2浓度变化规律基本一致。当土壤水分不足时,净光合速率主要受土壤含水率影响;当土壤水分充足时,净光合速率主要受光合有效辐射影响。气孔导度主要受光合有效辐射影响,地面灌溉条件下气孔导度对环境变化的响应更积极。蒸腾速率主要受土壤含水率和光合有效辐射的影响,土壤水分充足时,蒸腾速率对光合有效辐射的响应更敏感。相同条件下,土壤含水率越高蒸腾速率越大。

A Study on Leaf Photosynthesis Properties of Young Apple Trees at Different Lower Limit of Irrigation under Water Storage Pit Irrigation Conditions

The study subject of this paper is triennial dwarf stock Red Fuji apple trees.A portable LI-6400XT photosynthesis meter is employed in studying leaf photosynthesis properties of young apple trees at different lower limit of irrigation (corresponding to 50%,60%,or 70% field water capacity)under water storage pit irrigation conditions.The relationship between the influence fac-tors and the net photosynthesis is analyzed and quantified using path analysis and multivariate stepwise regression equations.The re-sults suggest:the net photosynthesis rate,the stomatal conductance,the transpiration rate,and the intercellular CO2 concentration of the leaves vary similarly to different lower limit of irrigation under water storage pit irrigation conditions.In the presence of insuf-ficient moisture,the net photosynthesis rate is primarily controlled by soil moisture or,in the presence of sufficient moisture,by photosynthetically active radiation (PAR).The stomatal conductance depends largely on PAR and responds more actively to environ-mental changes under surface irrigation condition.The transpiration rate is influenced mainly by soil moisture and PAR and becomes more sensitive to PAR in the presence of sufficient moisture.At a given condition,the higher the moisture content,the higher the transpiration rate.