基于叶气温差的温室作物水分胁迫指数的试验研究

Experimental Research on Application of Crop Water Stress Index in Greenhouse Based on Leaf-air Temperature Difference

在作物水分胁迫指标（CWSI）的计算中，需要确定Idso经验模型的下基线，下基线的精度影响着CWSI的计算结果。本文以设施温室内处于生长期的黄瓜幼苗作为测试对象，分析了太阳净辐射（Rn）和水汽饱和差（VPD）对叶气温差的影响，结果表明：在充分供水条件下，当Rn≥580～600μmol／m^2s时，黄瓜的叶温通常高于气温，造成Idso模型下基线的计算误差较大。叶气温差与Rn和VPD的线性相关，相关系数Rn分别为0．73和0．61。因此，文中以Rn和VPD为参数，建立了温室作物水分胁迫指标的下基线线性回归方程；dT1=8148～0．0033Rn-0．7778VPD。试验表明对比Idso经验模型中下基线的计算结果，该方程的计算值与测量值相关系数R^2达到0．8以上，有效提高了经验模型的计算精度。

In Idso experiential model, the lower baseline （Tc-Ta）n is very important in calculating CWSI because it is influenced by meteorological factors. This study evaluated the application in greenhouse, the experimental result showed： there is a striking positive correlation between leaf temperature （LT） and net radiation （Rn）, the correlation coefficient r=0. 78-0. 86. furthermore, under wellwatered, when Rn≥580-600μmol/m^2s, the LT of cucumber leaf was higher than air temperature （AT）, the result of the lower baseline equation existed error in measuring CWSI. According to ener gy balance equation, a linear regression equation for calculating （Tc-Ta）n was established, its equa tion basic model is= dT1=1. 8148-0. 0033Rn-0. 7778VPD, the checkout indicated that the （Tc- Ta）n with the linear regression equation was closer to the measurement than the calculating result with using the lower baseline equation of Idso.