Estimation Transpiration-water Requirement from An Apple Tree in Apple crop Intercropping System

The daily transpiration water requirement(TR)from an apple tree in Apple crop intercropping system was estimated using the modified model of transpiration from an apple tree (Thorpe,1978),and measured by LI 1600 steady state porometer.The main results were as follows:(1) The estimated value tallies well with the measured (R 2=0 966 4),and the average relative error between them was 7.93%.(2) Both EV×LAI and D×LAI tally with TR (EV:water surface evaporation;D:saturation pressure deficit of air; LAI:leaf area index per one tree);(3)A empirical model about TR and EV×LAI was developed,and the averaged TR was 5 546 mm·d-1 from April 1 to June 4 in 1998 according to the empirical model.