植物的水容特征与其耐旱性的关系

Relationship of hydraulic capacitance and draught endurance of plants

在自然风晾条件下，研究了不同植物器官的相对含水量、水势及比水容之间的相互关系。结果表明：植物叶片阻止体内蒸腾失水的能力大小顺序依次为：花生（Arrachishypogaea）＞甘薯（Ipomoeabatatas）＞大豆（Glycinemax）＞玉米（Zeamays），各植物茎的保水能力相差不大；甘薯的茎、叶在风晾4h后仍未永久凋萎，其他植物的茎、叶在风晾1～3h就出现永久凋萎；花生、甘薯、大豆和玉米叶片风晚3～4h后，其水势的下降幅度分别为：1．00，1．30，1．80和2．70mPa，花生、甘薯、大豆茎的水势下降幅度分别为：1．95，1.40和1．30mPa；植物茎、叶的水势与其相对含水量具有较好的对数关系；植株茎、叶的比水客值范围在0．0258～0．6835mPa-1之间，叶片的比水容大于茎的比水容。因此，植物的水容特征表明不同植物茎、叶的保水、释水能力不同，因而其耐旱、抗旱性不同。玉米和大豆的耐旱性小于花生、甘薯的耐旱性。

Under the simulated wind-dried condition with gentle breeze, the relationship of relative water content, water potential and specific capacitance of plants' leaf and stem was reported. The results showed that capacity of preventing water from loss through transpiration in leaf fell in the order of peanut (Arrachis hypogaea) (PN) > sweet potato (Ipomoea batatas ) (SP) > soybean (Glycine max ) (SB) > corn (Zea mays )(CN) and varied little in stem. Water content of SP in leaf and stem didn't reach the permanent wilting point even if SP was exposed 4 h in gentle breeze drying, but the others spent less than 1 ~ 3 h in the processing. Meanwhile, the decrease of water potential in leaf was 1. 00, 1. 30, 1. 80 and 2. 70 mPa for PN, SP, SB and CN, respectively, and in stem 1. 95, 1. 40 and 1. 30 mPa for PN, SP and SB, respectively.Plant water potential non-linearly correlated with relative water content in leaf and stem of the crops studied and specific capacitance ranged from 0. 0258 to 0. 6835 mPa-1 and the values of leaves were larger than those of stems. To sum up, properties of plant hydraulic capacitance indicated that the cpacities of water resistance and water release greatly varied with plants and, therefore, drought endurance of sweet potato and peanut was more powerful than that of corn and soybean.