基于冠层叶气温差的苹果园土壤水分预报模型

Model for predicting soil water status based on the canopy-air temperature differential in apple orchard

该研究于2003～2004年采用便携式红外测温仪观测得到苹果主要生长季节晴天14∶00时冠层叶温数据,结合同步观测得到的空气温度数据及0～80 cm土壤相对有效含水率, 分析、建立以苹果树冠层叶气温差为指标的果园水分预报模型.该模型中,土壤相对有效含水率和冠层叶气温差的相关系数为-0.819（n=50）,通过0.01水平显著性检验.并利用2002年及2005年的实测土壤水分数据对所建模型进行验证,结果表明：土壤相对有效含水率的观测值与计算值吻合较好,二者线性相关系数可达0.9137（n=40）.可见,采用14∶00时冠层叶气温差诊断苹果园土壤水分胁迫状况是可行的.

This study was conducted to develop a model for predicting soil water status in the apple orchard based on canopy-air temperature differential （AT） at 14 .00 o＇clock in the fine days during the growing season in combination of observed air temperature and relative available soil water contend in 0-80 cm soil layer in 2003-2004. Relative available water content（RAW） in 0-80 cm depth layer was chosen as the index of soil water status. The experiment was carried out in the hilly land of North China from 2002 to 2005. The results showed that： RAW and AT were significantly correlated （r =- 0. 819, n = 50）, according to the data in 2003- 2004, and were tested with the measured data in 2002 and 2005, indicating that the measured RAW was highly correlated with the simulated data （r = 0. 9137, n = 40）. Thus, the model can provide a valuable tool for diagnosing soil water status for apple trees. Based on this model, the critical AT could be calculated according to the critical RAW, and if the measured AT is larger than the critical AT, irrigation should be carried out in the orchard.