不同水分条件下核桃蒸腾速率与光合速率的研究

在黄土高原半干旱区,采用LI-1600稳态气孔仪和LI-6200便携式光合测定仪对不同土壤水分条件下盆栽核桃的生理指标进行了观测,研究土壤含水量对核桃蒸腾速率与光合速率的影响.结果表明,不同土壤含水量条件下核桃蒸腾速率、光合速率和水分利用效率的日变化具有显著的差异.当土壤体积含水量在5%以下时,核桃气孔导度很低,蒸腾速率日变化也不明显;当体积含水量为10%和15%时,蒸腾速率、光合速率和水分利用效率随着土壤水分的增加而升高,而且具有明显的日变化.土壤含水量越低,核桃叶片气孔导度与蒸腾速率和光合速率的相关性越差.通过对比得出,核桃光合作用适宜土壤体积含水量为10%～15%;土壤体积含水量控制在15%时核桃的水分利用效率达到较好状态.

Study on Transpiration Rate and Photosynthesis Rate of Juglans regia under Different Soil Water Contents

In semi-arid area of the Loess Plateau,physiological indicators of Juglans regia under different soil water conditions were measured by portable steady porometer(LI-1600) and portable photosynthesis system(LI-6200).The effects of soil water on transpiration rate and photosynthesis rate of Juglans regia were studied.The results showed that there were obvious differences among transpiration rate,photosynthesis rate and water use efficiency of Juglans regia in daily variation under different soil and water condition.When soil water content(SWC) was below 5%,stomata conductivity of Juglans regia was very low,and the variation of transpiration rate was not obvious in a day.When SWC was at 10% and 15%,transpiration rate,photosynthesis rate and water use efficiency increased with the increase of SWC,and their variations were significant in a day.As soil water content decreasing,the correlation between stomata conductivity and transpiration rate and photosynthesis rate of Juglans regia was gradually decreased.By comparison,when 10%