Abstract: A field experiment has being conducted for 27 years in Jinxian County, Institute of Red Soil in Jiangxi Province (116°20′24″ E, 28°15′30″ N) to study the effects of fertilization on the rice photosynthetic traits and water use efficiency. Four treatments were installed, i.e., no fertilization (CK), chemical fertilization (N, NP, NPK), organic fertilization (M), and chemical and organic fertilization (NPKM). Longterm fertilization, especially treatment NPKM, increased the flag leaf chlorophyll content, net photosynthetic rate, stomatal conductance, transpiration rate, and water use efficiency of rice at its all growth stages and the rice yield, and decreased the flag leaf intercellular CO₂ concentration. With the growth of rice, the chlorophyll content, net photosynthetic rate, stomatal conductance, and transpiration rate decreased, but the intercellular CO₂ concentration increased. The water use efficiency was the greatest at full heading stage. There were significant positive correlations between the chlorophyll content and net photosynthetic rate at various growth stages and the rice yield. Long-term fertilization, especially the combined chemical and organic fertilization, was favorable to the rice growth and development, water use efficiency, and yield production in red soil region.

Key words: Hainan Island, SOTER digital databases, Diversity index, Soil chemical properties, Landforms, Abundance distribution models, GIS spatial analysis