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Effects of environmental factors on permeability of soybean roots to water and solute

环境因素对大豆根系水分和溶质渗透性的影响

基本信息

批准号：
07456119
负责人：
NAGANO Toshihide
金额：
$ 0.83万
依托单位：
TOKYO UNIVERSITY OF AGRICULTURE
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1997
项目状态：
已结题

项目摘要

The effect of thermal factors on resistance to water flow through soybean root system was measured. Total resistance of root system are divided to absorptive (radial) resistance and conductive resistance (=longitudinal) one. The total resistance increases with similar rate to water viscosity as temperature in root system decreases above 13ﾟC . While, the toal resistance increases sharply as temperature decreases below 13ﾟC.Thus, the principla cause of the increase in total resistance over 13ﾟC is the temperature dependency of water viscosity. However the principle cause is the change of permeability of cell membrane itself below 13ﾟC.The conductive resistance changes with similar rate to water viscosity as temperature changes in any range. The absorptive resistance changes with similar rate to water viscosity as temperature changes above 13ﾟC C to 23ﾟC.While, it increases sharply as temperature decreases below 13ﾟC.Thus, the temperature, 13ﾟC,is the threshold for water permeability of soybean root membrane and the change in the permeability seems to be the main cause of the sharp change of the total resistance.The contributing ratio of the absorptive resistance to the total resistance is almost constant at 75% from 13ﾟC to 23ﾟC,while the ratio increases sharply and increases up to 90% at 8ﾟC.The conductive resistance in xylem cannot neglect at any temperature for normal growing condition of soybean. Temperature dependency of both absorptive and conductive resistance must be taken into account to simulate the water flux through SPAC.In this research, we focused on lower temperature condition. Similar threshold could exist in higher temperature condition and should be found out. Also, the relation between appropriate temperature for plant growth and these thresholds should be found out. The research could make it clear what the proper temperature for plant growth means.

测定了温度因子对大豆根系导水阻力的影响。根系总阻力分为吸收(径向)阻力和传导(=纵向)阻力。当根系温度降低到13ﾟC以上时，总阻力以与水分粘度相近的速度增加。当温度低于13ﾟC时，总阻力急剧增加。因此，总阻力高于13ﾟC的主要原因是水粘度与温度的依赖关系。然而，其主要原因是细胞膜本身的透性在13ﾟC以下发生变化。在任何温度范围内，电导电阻与水粘度的变化速率相似。在13ﾟC~23ﾟC温度范围内，大豆根膜的吸收阻力随温度的变化与水的粘度变化速度相近，而在13ﾟC以下则急剧增加。13ﾟC是大豆根膜透水性的阈值，透性的变化似乎是总阻力急剧变化的主要原因。在13ﾟC~23ﾟC温度范围内，吸收阻力占总阻力的贡献率几乎为75%。而在8ﾟ℃时，木质部的导热电阻急剧增加，达到90%。通过SPAC模拟水通量时，必须同时考虑吸收电阻和传导电阻对温度的依赖关系。在较高的温度条件下，可能存在类似的阈值，应找出。此外，还应找出植物生长的适宜温度与这些阈值的关系。这项研究可以清楚地说明植物生长的适宜温度意味着什么。