Abstract:In order to understand the effect of phosphorus fertilizer on rice (Oryza sativa) grown in cold waterlogged paddy field, the phosphorus content, photosynthesis characters and yield were studied under four levels of phosphorus fertilizer. The results showed that the phosphorus contents in roots, stems and leaves, net photosynthetic rate of leaves treated with phosphorus fertilizer at tillering stage were higher than those of control by 10.53%-36.84%, 18.52%-37.03% and 15.17%-29.88%, respectively. At heading stage, the phosphorus contents in roots, stems and leaves, and panicles, net photosynthetic rate and soluble sugar content of leaves increased by 11.76%-23.53%, 24.13%-41.38%, 9.68%-22.58%, 13.41%-27.10% and 6.03%-22.38%, respectively, but the starch content reduced by 12.05%-41.77%. At mature stage, the phosphorus content of panicles and yield increased for 0.71%-28.57% and 4.65%-10.32%. There was regression equation between phosphorus fertilizer dosage (X) and rice yield (Y): Y=-0.0835X2+14.224X+6530.9 (r=0.94*). The coefficients between rice yield and net photosynthetic of leaf, phosphorus content of stems and leaves at heading stage were 0.57* and 0.77*, respectively. Therefore, phosphorus fertilizer could improve phosphorus content of rice, net photosynthetic and soluble sugar content in leaves, reduce starch accumulation in leaves, thus improve rice yield. Heading stage was an important period for rice yield. It could be used as diagnostic reference index that the phosphorus content in stems and leaves was about 0.38%. The optimal dosage of phosphorus fertilizer is 85.17 kg hm-2 for cold-waterlogged paddy field.
