土壤水分与温度共同作用对植物根系水分传导的效应

 本文根据不同大气环境温度和土壤温度及不同土壤含水率处理条件下的玉米、向日葵、台湾相思(Acacia confusa)、银合欢(Leucaena glauca)的试验资料，分析了土壤水分和温度以及土壤水分与温度共同作用对植物根系水分传导的效应。台湾相思和银合欢的试验结果表明，在一定的土壤水分范围内，高温(白天/夜晚的温度为40／30℃)环境中的根系水分传导大于低温(30/25℃)环境中的，但当根系水分胁迫十分严重(台湾相思根系水势小于-1.5MPa，银合欢根系水势小于-2.0MPa)时，30/25℃环境的根系水分传导反而大于40／30℃环境的；玉米、向日葵的试验结果表明，在一定土壤温度范围内，根系水分传导随土壤温度增加而增加，其增加的幅度与生育阶段有关；在向日葵生育期土壤温度高于35℃、玉米生育期高于30℃时，其根系水分传导随温度增加而降低。通过植物根区土壤逐渐干旱和干旱复水后的试验，其结果表明复水后根系水分传导上升较快，银合欢复水1.5d、向日葵复水3d后测得的根系水分传导即可达到受旱前的水平，其后的水分传导还略高于一直充分供水处理的，表明根系经受一定程度的干旱锻炼后，对其水分传导具有明显的补偿效应。在干旱和复水过程中根系水分传导与根水势的变化规律相一致。

COMBINED EFFECTS OF SOIL WATER CONTENT AND TEMPERATURE ON PLANT ROOT HYDRAULIC CONDUCTIVITY

In this paper, based on the experimental data of maize, sunflower, Acacia confusa and Leucaena glauca under various treatments of air and soil temperature as well as soil water content, the effects of soil water content and temperature on plant root hydraulic conductivity (LR) were analyzed. The results indicate that LR in 40/30℃ (day/night air temperature) was larger than that of 30/25℃ air temperature when soil moisture was suitable for plant growth. When root water stress was very serious, i.e. the root water potential was lower than -1.5 and - 2.0 MPa for Acacia confusa and Leucaena glauca respectively, the LR in 30/25℃ air temperature was larger than that of 40/30℃ air temperature. And also the root hydraulic conductivity increased with soil temperature(Ts) increasing when Ts was lower than 35℃ for sunflower and 30℃ for maize growing season. When Ts was higher than that values, LR would decrease with temperature increasing continuously. LR increased quickly when root was rewetted after it was encountered soil-drying process. LR would reach the values before soil-drying, after 1.5 days and 3 days rewetting to Leucaena glauca and sunflower respectively. After that, it was larger than that before soil-drying. The changes of root hydraulic conductivity during soil-drying process and after rewetting were similar to the change process of root water potential.