通过刺槐的水力结构特征参数探讨管道理论

The pipe model theory based on the hydraulic architecture parameter with Robinia pseudoacacia seedlings

为了解刺槐Robinia pseudoacacia苗木对体内水分运输过程的调控机制,基于水力结构理论,在充分供水条件下,利用改良的"冲洗法"对2年生刺槐苗木的水力结构参数进行测定,并探讨了管道理论的合理性和适用范围。结果表明:在充分供水条件下,刺槐苗木茎段导水率、比导率、叶比导率和胡伯尔值均随被测茎段直径的增加而增大;苗木不同生长阶段,其导水率、比导率和叶比导率差异显著(P<0.05),且均为生长旺期>生长初期>生长末期,胡伯尔值为生长初期最大,生长旺期和生长末期差异不显著(P>0.05)。由此可推断,①在水分胁迫条件下,苗木更倾向于保护那些较粗茎段;②苗木水力结构特征与提体内生理活动呈正相关关系;③管道模型假说虽然有其存在的合理性,但也有其局限性和适用性,在对于水分在林木体内的运输过程以及调控机制的解释,管道模型假说过于简单化了。

To better understand the pipe model theory and hydraulic architecture characteristics of Robinia pseudoacacia seedlings in different growth stages （early,fast,and last）,the improved flushing method was used to measure the hydraulic architecture parameters of two-year-old R.pseudoacacia seedlings with an adequate water supply for three growth stages（early,fast,and last） and there are 20 repeats in every growth stages.Significance tests were done between hydraulic architecture parameters and stem segment diameter and different growth stages by ANOVA.Then the pipe theory was discussed based on hydraulic architecture theory.Results showed that with sufficient water,the hydraulic conductivity （Kh）,stem area specific hydraulic conductivity （Ks）,leaf specific conductivity （K1）,and Huber value （Hv） of R.pseudouacacia seedlings increased （P＜0.05）as the stem segment diameter enlarged.For the three seedling growth stages,Kh,Ks,and K1 were significantly different （P＜0.05） with early growth stage＞fast growth stage＞last growth stage.Hv was greatest （P＞0.05） in the early growth stage with no significant differences in fast and last growth stages.Thus,（1） with sufficient water,water transportation efficiency of thicker stems is greater than the thinner stems; （2） hydraulic architecture characteristics of seedlings were different （P＜0.05） in three growth stages; and （3） the pipe model theory was not perfect,especially for understanding the inner water transportation processes of a tree and their control mechanism.