中文摘要：

以宁7414为对照,在大田栽培条件下,研究了优质高产早熟晚粳品种南粳44在不同施氮水平（LN：150.0 kg·hm-2,MN：300.0 kg·hm-2,HN：450.0 kg·hm-2）下分蘖期、拔节期和开花后的生长和光合生理指标,鉴定了植株的耐光氧化和耐阴特性,并在成熟期考察其产量构成因子。结果表明,与宁7414相比,在HN、MN和LN下,南粳44单株产量分别提高了18.33%、9.37%和16.67%;在不同生育期以及不同的施氮量,均具有较高的光合能力,尤其在开花后14 d,南粳44的最大光合速率（Pmax）在LN、MN和HN下分别比对照的高3.86%、10.78%和6.13%;而在人工光氧化处理后,南粳44的最大光化学效率（Fv/Fm）与对照无显著差异;在遮阴条件下,Pmax、结实率较高,属于耐光氧化和耐阴品种类型。南粳44的高光合能力和广幅光强适应性,可能是其在不同氮素水平下获得高产的重要生理基础。

英文摘要：

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 kg·hm-2,MN at 300.0 kg·hm-2 and HN at 450.0 kg·hm-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.