基于Δ^(13)C的不同水氮管理对水稻水分利用效率的影响

Effect of Different Water and Nitrogen Managements on Rice Leaf Water Use Efficiency Based on Δ^(13)C

为揭示不同水氮管理的水稻叶片水分高效利用机理,基于作物生长发育过程中发生的碳同位素分馏效应对作物的长期水分利用效率的指示特性,研究了不同水氮管理对水稻叶片气体交换参数、叶片瞬时水分利用效率(LWUEins)、内在水分利用效率(LWUEint)和碳同位素分辨率(Δ^(13)C)的影响,分析了不同水氮管理下水稻叶片Δ^(13)C与叶片水分利用效率关系。结果表明:稻作控制灌溉模式下配施适量氮肥可以提高水稻叶片气孔导度(Gs),促进叶片胞间与外界气体交换,提高叶片净光合速率(Pn),维持较高的LWUEins、LWUEint,过量施氮会增加水稻对水分亏缺的敏感性,使水稻Gs降低,不利于叶片尺度水分的高效利用;抽穗开花期控制灌溉模式下施氮量较高时叶片水分利用效率较大,同一施氮量处理控制灌溉水稻LWUEins、LWUEint和WUE均高于淹水灌溉,起到了节水高产的效果。通过统计分析可知,不同水氮管理下抽穗开花期水稻叶片Δ^(13)C与LWUEins、LWUEint和WUE均呈负相关,叶片Δ^(13)C对LWUEint的指示性优于LWUEins,且在控制灌溉下叶片Δ^(13)C与LWUEins、LWUEint的相关性较淹水灌溉更为显著;拔节孕穗期及抽穗开花期水稻叶片Δ^(13)C可以很好地表征水稻WUE。结果表明,通过测定水稻不同时期叶片Δ^(13)C能够为预测不同水氮调控下水稻水分利用效率提供参考。

In order to further investigate the high water use efficiency mechanism under different water and nitrogen managements,theoretical analysis was combined with field experiments,and water use efficiency research on leaf scales was integrated through carbon isotope ＇s instruction on water use efficiency based on carbon isotopic factor effect during crop growth and development. The effects of different water and nitrogen managements on gas exchange parameters,instantaneous water use efficiency（ WUEins）,intrinsic water use efficiency（ WUEint） and carbon isotope discrimination（ Δ^（13）C） were examined,and then the relationship between Δ^（13）C in rice leaf with WUEinsand WUEintat leaf scale was analyzed to further explain the water use process in crop leaf under different water and nitrogen managements. The result showed that the appropriate amount of nitrogen fertilizer could increase the stomatal conductance（ Gs） of leaves of rice,promote the exchange of leaf cells with outside world,increase the net photosynthetic rate（ Pn）,and maintain high WUEintand WUEinsunder controlled irrigation. Excessive application of nitrogen would increase the sensitivity of rice to water deficit,so that Gsof rice leaves was reduced,which was not conducive to the efficient use of water at leaf scale. The leaf water use efficiency and yield were the highest when the nitrogen application rate was high at the heading stage,and WUEint,WUEinsand WUEETof the same nitrogen treatment of controlled irrigation for rice were higher than those of flood irrigation,which played water saving and high yield effect. The statisticalanalysis result indicated that leaf Δ^（13）C showed a negative relationship with WUEint,WUEinsand WUEET respectively at heading stage under different water and nitrogen managements. Leaf Δ^（13）C showed a better indicating capacity on WUEintthan that on WUEins. Furthermore,the correlation between leaf Δ^（13）C and WUEins,WUEintunder controlled irrigation was more significant than that under flooding irrigation; the leaf Δ^（13）C values can well characterize rice WUEETduring the period of booting and heading. In conclusion,using rice leaf Δ^（13）C values to indicate water use efficiency at leaf levels had a certain feasibility under different water and nitrogen managements.