Effects of different levels of phosphorus nutrient on the photosynthesis characteristic of rice flag leaf

[Objective] To provide scientific basis for high phosphorus efficiency cultivation and regulation of rice. [Method] Changbai9 (CB9) and Jijing81 (JJ81) were used as experimental materials for pot experiment, and five levels of phosphorus nutrient (P0-P4) were set for each variety, the net photosynthesis rate, Chlorophyll Meter Readings (SPAD Readings), stomatal conductance, transpiration rate, intercellular CO2 concentration, and stomatal limitation were observed and compared between five different phosphorus levels at filling stage. [Result] The net photosynthesis rate of CB9 reached the highest at P3, and was significantly different from other treatments (P0.05)；the net photosynthesis rate of groups with phosphorus ofJJ81 were higher than that of the control group，and reached the highest at P4. The SPAD Readings of CB9 and JJ81 all achieved the highest at P3, and stomatal conductance and transpiration rate were all at first increased then decreased with the phosphorus increased in CB9 and JJ81. With the pho