[1] [1] Minolta Camera Co. Ltd. Chlorophyll meter SPAD-502. Instruction Manual. Radiometric Instruments Divisions, Osaka, Minolta. 1989.

[2] [2] WU Fei-bo, WU Liang-huan, XU Fu-hua. Field Crop Res., 1998, 56: 309.

[3] [3] Chang S X, Robison D J. Forest Ecol. Manag., 2003, 181: 331.

[4] [4] Lopez-Bellido R J, Shepherd C E, Barraclough P B. Eur. J. Agron., 2004, 20: 313.

[5] [5] Li X L, He Y. Hort Science, 2008, 43(5): 1586.

[7] [7] Noh H, Zhang Q, Shin B, et al. Biosystems Eng., 2006, 94(4): 477.

[8] [8] Young Yeol Cho, Sungbong Oh, Myoung Min Oh, et al. Sci. Hortic., 2007, 111: 330.

[9] [9] William L Bauerle, David J Weston, Joseph D Bowden, et al. Sci. Hortic., 2004, 101: 169.

[10] [10] Pinkard E A, Patel V, Mohammed C. Forest. Ecol. Manag., 2006, 223: 222.

[11] [11] Hoel B O, Solhaud K A. Ann. Bot., 1998, 82: 389.

[14] [14] Shao Yongni, He Yong, Mao Jingyuan. Applied Optics, 2007, 46(25): 6391.