96 J.Bai.J.Li,and S.Li May24:N=12.13DEVM+1.13 R2=0.34 (10) June 9th:N =2.82DEV1+1.31 R2=0.27 (11) June 25th N.2.65DEV/+0.64 R2=0.34 (12) PDC estimation based on the data from middle c n PDC and DEvI from .From Fig,the mized on May Juneand and the dete th extremel leve co046 0.76 Unfortu esn't reach the significan May24:N,=10.95DEV+l.147 R2=0.46* (13) June9h:N=4.114DEV7+0.980 R2=0.76* (14 June25:N.=3.174DEV7+0.329 R2=0.67 (15) Table 1.Testing about the different models of estimating PDC Time The estimating The regress equations between measured RMSE methods REPE and estimated values y=0.184x+1.507R2=0.181 0.301 27.1 May 24 y=0.454x+0.939(R2=0.418 0.248 22.7 I y=0.252x+1.393(R2=0.293" 0.280 25.7 白 y=0.711x+0.446(R2=0.656” 0.205 18.7 Ⅲ y=0.282x+1.342(R2=0.274) 0.282 25.4 N y=0.727x+0.408(R2=0.660” 0.207 18.7 y=0.322x+1.279(R2=0.466 0.253 23.2 y=0.559x+0.718(R2=0.664” 0.208 19.1 June 25 y=0.307x+1.317R2=0.431 0.259 23.3 y=0.599x+0.636(R2=0.647” 0.213 19.2 Noting:/shows the testing result based on EVI from the early,middling and late emergence stage: shows the testing result based on EVI form the middling emergence stage:I shows the testing result base .midling and late emrgence stage:shows the testing based DEV 96 J. Bai, J. Li, and S. Li May 24th : Nu = 12.13DEVI+1.13 R2 = 0.34 ** (10) June 9th : Nu = 2.82DEVI+1.31 R2 = 0.27** (11) June 25th : Nu = 2.65DEVI+0.64 R2 = 0.34** (12) PDC estimation based on the data from middle emergence stage. From Fig.3, the linear correlations between PDC and DEVI from middle emergence stage are opti￾mized on May 24th, June 9th and June 25th, and the determination coefficients reach the extremely significant level and rise to 0.46, 0.76 and 0.67 distinctly. Unfortu￾nately, the coefficient on July 11th doesn’t reach the significant level. The estimation models on PDC with DEVI as below: May 24th : Nu = 10.95 DEVI+1.147 R2 = 0.46** (13) June 9th : Nu = 4.114 DEVI+0.980 R2 = 0.76** (14) June 25th : Nu = 3.174 DEVI+0.329 R2 = 0.67** (15) Table 1. Testing about the different models of estimating PDC Time The estimating methods The regress equations between measured and estimated values RMSE REPE Ⅲ y = 0.184x+1.507 (R2 = 0.181* ) 0.301 27.1 May 24 Ⅳ y = 0.454x+0.939 (R2 = 0.418**) 0.248 22.7 Ⅰ y = 0.252x+1.393 (R2 = 0.293**) 0.280 25.7 Ⅱ y = 0.711x+0.446 (R2 = 0.656**) 0.205 18.7 Ⅲ y = 0.282x+1.342 (R2 = 0.274**) 0.282 25.4 June 9 Ⅳ y = 0.727x+0.408 (R2 = 0.660**) 0.207 18.7 Ⅰ y = 0.322x+1.279 (R2 = 0.466**) 0.253 23.2 Ⅱ y = 0.559x+0.718 (R2 = 0.664**) 0.208 19.1 Ⅲ y = 0.307x+1.317 (R2 = 0.431**) 0.259 23.3 June 25 Ⅳ y = 0.599x+0.636 (R2 = 0.647**) 0.213 19.2 Noting: Ⅰ shows the testing result based on EVI from the early, middling and late emergence stage; Ⅱ shows the testing result based on EVI form the middling emergence stage; Ⅲ shows the testing result based on DEVI from the early, middling and late emergence stage; Ⅳ shows the testing result based on DEVI from the middling emergence stage