高光效水稻品种的叶片和冠层生理生态特征及其氮素调控机制研究进展

Advances in Leaf and Canopy Eco-physiological Characteristics of High Photosynthetic Efficiency Rice Varieties and Their Regulation Mechanisms by Nitrogen

提高水稻的光合效率被认为是进一步提高水稻产量的有效途径之一。然而,关于高光效水稻品种的生理生态特征还不清楚,无论是在单叶水平还是群体冠层水平上。本文综述了叶片Rubisco酶含量和活性、叶片含氮量、叶片形态解剖结构包括气孔性状、叶脉性状和叶肉解剖结构以及结构性物质与功能性物质之间的平衡对单叶光合作用的影响,冠层结构和冠层光氮匹配对群体冠层光合作用的影响及其受氮素调控的状况,总结了高光效水稻品种的叶片和冠层生理生态特征及其氮素调控效应。高光效水稻品种叶片Rubisco酶含量和氮含量高,气孔密度和孔径大,细胞间隙比例大,叶绿体覆盖率大,叶肉细胞和叶绿体面向细胞间隙的比表面积大,细胞壁薄,叶脉密度大,叶脉维管直径大,根系表面积大,根直径大,叶片挺、叶色深,冠层下部叶片多,冠层光氮匹配程度高等;增施氮肥可以增加叶片Rubisco酶含量和活性,提高叶肉层厚度,增加叶绿体覆盖率、叶肉细胞和叶绿体面向细胞间隙的比表面积,降低细胞壁厚度,提高叶绿素含量,减少细胞壁含量等,从而增强叶片光合作用,但是,过量施氮会降低氮肥利用效率,造成氨挥发、水体富营养化、N_(2)O排放增加等一系列环境问题。

Increasing the photosynthetic efficiency of rice is regarded as one of the most promising approaches to further improving rice yield.However,the eco-physiological characteristics of rice varieties with high photosynthetic efficiency are not well understood,both at the single leaf level and the group canopy level.This work reviews the influences of Rubisco enzyme content and activity,leaf nitrogen content,and various leaf morphological and anatomical traits,including stomatal traits,leaf vein traits,and leaf mesophyll anatomical traits on single leaf photosynthesis.It also examines the effects of canopy architecture and canopy light-nitrogen matching on group canopy photosynthesis,as well as their regulation by nitrogen.We summarize the leaf and canopy eco-physiological characteristics of high photosynthetic efficiency rice varieties and their regulation by nitrogen.We conclude that high photosynthetic efficiency rice varieties exhibit high leaf Rubisco and nitrogen contents,high stomatal density,and large stomatal pore size.They also have a large proportion of intercellular airspace,a significant coverage of chloroplasts,a large surface area of mesophyll cells and chloroplasts facing intercellular airspace per leaf area,thin cell walls,high vein density,large vascular diameters of veins,large root surface area,large root diameters,straight leaves,deep leaf color,and more leaves in the lower part of the canopy,along with a high degree of canopy light-nitrogen balance.Increasing nitrogen fertilizer can enhance the content and activity of leaf Rubisco,increase the thickness of the leaf mesophyll layer,improve chloroplast coverage,enlarge the surface area of mesophyll cells and chloroplasts facing intercellular airspace per leaf area,reduce cell wall thickness,increase chlorophyll content,and decrease cell wall content,thereby improving leaf photosynthesis.However,excessive nitrogen application can reduce nitrogen use efficiency,leading to a series of environmental issues such as ammonia volatilization,water eutrophication,and increased N_(2)O emissions.