Effect of Reduced Phosphorus Fertilizer Application on Yield Formation and Quality of japonica Rice in Jiangsu Coastal Region

Soil available phosphorus content of farmland has reached a high level in Jiangsu coastal area due to long-term application of large amounts of phosphate fertilizer.But current higher rates of phosphate fertilizer decreases the phosphorus effect,even having an adverse effect on the surrounding water environment.A field experiment was conducted to investigate the effect of reduced phosphorus fertilizer application on the yield formation and quality in rice.Six treatments were designed as CK(no fertilization),conventional NPK fertilizer application,no phosphorus fertilization,reduced P rate(50% of conventional phosphorus fertilization rate),conventional phosphorus fertilization,increased P rate(150% of conventional phosphorus fertilization).The results showed that there were no significant difference in SPAD of rice leaves among all the treatments except CK at jointing,heading,middle and late filling stages.The dry matter accumulation at jointing,heading stage,maturity stage and net dry matter accumulation as well as net population growth rate during jointing-heading,heading-maturing had also no significant difference among all the treatments except CK.The 1000-grain weight under no or reduced phosphorus treatments was significantly lower than that of conventional phosphorus treatments,while the rest of yield components as well as economic coefficient had no significant difference among the treatments.Due to higher effective panicle number,grain number per panicle and 1000-grain weight,the rice grain yield under reduced phosphorus treatment reached 9801kg/hm2,7.69% higher than that under the conventional phosphorus treatment.There were no significant differences in the indexes of rice quality except that the chalky grain rate under the reduced phosphorus treatment was significantly higher than CK.Due to higher peak viscosity and breakdown and lower setback value,the eating quality of rice under the reduced phosphorus treatment was improved.