水分胁迫对不同根型小麦幼苗水分利用率和导水率的影响

以旱地小麦晋麦47和高水肥小麦石4185为试材,比较分析了充分供水和模拟干旱胁迫条件下小麦幼苗水分利用效率(WUE)和根系导水率(Lpr)的差异。结果表明:正常供水条件下,晋麦47单株耗水量、根系干质量和单株干质量皆低于石4185,但根系水分利用率(WUEr)、茎叶水分利用率(WUEs)、单株水分利用率(WUE)以及根系导水率均高于石4185。轻度干旱胁迫下,石4185根系干质量稍有增加,晋麦47变化不明显,两者单株干质量均降低;两品种根系、茎叶和单株水分利用效率均显著提高,石4185根系水分利用效率反而高于晋麦47;但两品种根系导水率呈显著下降趋势,晋麦47下降幅度大于石4185并最终低于石4185。以上说明:水分充足条件下,晋麦47表现出“奢侈”利用水分,干旱条件下,表现出以降低水分消耗而维持地上部生长的耐旱节水机制;石4185在水分充足条件下耗水量大,表现出水地品种特点,胁迫条件下,水分利用率均升高且根系水分利用率升高相对更大,体现出干旱胁迫下依赖根系进一步发展增大吸收水分表面积来适应缺水环境。两者相比较,体现了不同根型小麦品种根系在干旱胁迫调节中的重要性和差异性。

Effects of Osmotic Stress on Water Use Efficiency and Root System Hydraulic Conductivity of Winter Wheat of Different Root Types

In this report we performed a comparative study on the water use efficiency(WUE),root system hydraulic conductivity(Lpr)between the seedlings of two different wheat variety Jinmai47 and Shi4185 in adequate water condition and simulated drought stress condition.In normal water supply condition,water consumption,root dry weight,biomass per plant of Jinmai47 was lower than of Shi4185,but the water use efficiency in root(WUEr),water use efficiency in stem(WUEs),WUE per plant,root system hydraulic conductivity in the former were higher than in the later;compared to the situation in normal water supply condition in moderate drought stress condition,the root dry weight of Shi4185 increased moderately yet the root dry weight of Jinmai47 did changed,biomass of per plant of both varieties reduced,the water use efficiency in root,in stem or whole plant became higher significantly.An interesting observation in this stress condition was that the water use efficiency in root of variety Shi4185 was higher than of Jinmai47.root system hydraulic conductivity in both varieties reduced and in Jinmai47 reduced more in degree than in Shi4185 resulting in a lower root system hydraulic conductivity in Jinmai47 than in Shi4185.These results showed that : in adequate water supply condition,Jinmai47 used water wasteful yet facing drought stress it could reduce transpiration to save water resulting in survival of plant on the earth;in adequate water supply condition,Shi4185 consumed a lot of water while in drought stress condition it used water more efficiently more ever the water use efficiency in root increased significantly suggesting it could enlarge its root system to absorb water responsing to drought stress compared with to which in normal water supply condition.In summary,our study indicated that the root system plays an critical role in drought stress response of wheat and the different root systems of different varieties response differently to drought stress.