Correlation Between Photosynthesis and Yield of Japonica Rice Cultivar,Nanjing 44,with Different Nitrogen Fertilizations

Using Ning 7414 as the control,a good quality,high yield,fast mature and late season Japonica rice variety,Nanjing 44,was applied for the study.The photosynthetic characteristics of the rice plants at tiller,jointing and post-flowering stages were compared with varied nitrogen fertilizations(i.e.,LN at 150.0 kgm-2,MN at 300.0 kgm-2 and HN at 450.0 kgm-2).The rice yield components were examined at harvest.In addition,tolerances to photo-oxidation and shading of the rice were identified.The results showed that,as compared with Ning 7414,the per plant yield of Nanjing 44 increased 18.33%,9.37% and 16.67% for HN,MN and LN,respectively.It also had better photosynthetic capacity during growth period with different nitrogen applications.Particularly,Pmax of Nanjing 44 in 14 days after flowering increased by 3.86%,10.78%,6.13% for HN,MN and LN,respectively.After the photo-oxidation treatment,the Fv/Fm ratio of Nanjing 44 decreased less,as compared to the control.Under the shading treatment,the seed setting rates and dry matter accumulation of Nanjing 44 also decreased less than the control.That made the cultivar a moderately photo-oxidation and shade-tolerant variety.The high photosynthetic traits and broad range of light intensities for optimal growth of Nanjing 44 might have provided an important physiological edge over the control for the high yield under different N fertilizations.