Effects of soil water stress on the photosynthesis characteristics and chlorophyll fluorescence parameters of Cerasus humilis seedling
Chu-Jian-Min; Meng-Ping; Zhang-Jin-Song; Gao-Jun
Forest Research 21(3): 295-300
Both Li-6400 photosynthesis system and OS1-FL chlorophyll fluorometer were used to measure the photosynthesis characteristic and chlorophyll fluorescence parameters of Cerasus humilis plant under soil water stress. The result showed: ( 1) The average photosynthesis rate reached the maximum under the low water. stress, while that under the high soil water stress was the least. The stomatal conductance increased as a result of the increasing of PAR ( Photosynthetically Active Radiation) under no soil water stress conditions and didn't variate under the mediums and high soil water stress conditions. Diurnal variation of photosynthesis rate presented a two-peaks curve and showed obvious noon depression. The variation of net photosynthesis rates under different water stress conditions are follows: 8. 447 +/- 0. 831 6. 811 +/- 0. 690,2. 658 +/- 0. 756,1. 474 +/- 0. 469 mu mol center dot m(-2).s(-1). Significant variations of Pn happened between the conditions of the former two and the later two, Diurnal variations of Cond, Tr, WUE under different soil water stress. conditions were similar to the variations of Pn. ( 2) The. fluorescence parameter of Fo, NPQ increased with the increasing of water stress, while the Fv/Fm, Fv/Fo dereased.