限根条件下供氮对玉米光合作用有关生理特性的影响  

Effect of nitrogen on some physiological characteristics in relation with photosynthesis of maize under restricted roots

作　　者：宋海星[1] 李生秀[1] 

机构地区：[1]西北农林科技大学资源环境学院

出　　处：《干旱地区农业研究》2004年第4期28-32,共5页Agricultural Research in the Arid Areas

基　　金：国家重点基础研究专项(G1999011707);国家自然科学基金重点项目(30230230);面上项目(30070429;40201028)资助。

摘　　要：以玉米为供试作物,在遮雨棚内进行了微区田间试验,在不同水分与供氮条件下,分期测定了玉米自由水与束缚水比值和细胞汁液浓度、气孔导度和细胞间隙CO2浓度、核酮糖-1,5二磷酸羧化酶(RuBPCase)活性和叶绿素含量、以及叶片的光合速率和作物产量,研究供氮对玉米光合作用有关生理特性的影响。结果表明,氮素对光合生理特性的影响受水分供应状况的制约:水分供应较好时,供氮提高了叶片自由水与束缚水比值,降低了叶肉细胞汁液和细胞间隙CO2浓度;增加了气孔导度,提高了RuBPCase活性和叶绿素含量,既有利于改善气孔因素,也有利于改善非气孔因素,显著提高光合速率和作物产量。水分胁迫较轻时,供氮降低了气孔导度,增加了CO2进入气孔的阻力,不利于光合作用,但却提高了叶片自由水与束缚水比值,降低了叶肉细胞汁液和细胞间隙CO2浓度,增加了RuBPCase活性和叶绿素含量。在这种情况下,光合作用的气孔因素受到影响,非气孔因素不但没有减弱,反而有所增强,因而光合速率和产量都有所提高。水分胁迫严重时,供氮不但抑制了光合作用的气孔因素,还更严重地抑制了非气孔因素,导致光合速率和作物产量严重下降。供氮对光合作用影响的水分依赖性为调控氮素营养提供了有力依据。A field experiment with micro-plots was conducted under rain-preventing condition for studying the effects of N supply on some physiological characteristics related with photosynthesis of maize. With application of different rates of N and water, determinations were made for the ratio of free water to bound water in leaves, cell sap concentrations, stomatal conductance, intercellular CO_2 concentrations, RuBPCase activity, chlorophyll contents, leaf photosynthesis rate at different time, and finally the biomass yields. The results showed that the effect of N on photosynthesis was determined by water supply. When water supply was relatively sufficient, input of N raised the ratio of free water to bound water in leaves, decreased sap in diachyma cells and intercellular CO_2 concentrations, raised stomatal conductance, RuBPCase activity and chlorophyll contents. This was not only beneficial to improvement of the stomatal factors but also to the non-stomatal factors, and consequently resulted in significant increase in photosynthesis rate and biomass production. When water was slightly stressed, input of N decreased stomatal conductance, and increased the resistant force for CO_2 entering stomata, being detrimental to photosynthesis, but it raised the ratio of free water bound water, decreased in diachyma cells sap concentration and intercellular CO_2 concentration as well as RuBPCase activity and chlorophyll contents. In this case, N input mainly affected the stomatal factors of photosynthesis, but the non-stomatal factors were not decreased, but increased, and therefore photosynthesis rate and biomass were raised. In contrast, when water was seriously stressed, input of N did not only inhibit the stomatal factors but also seriously inhibited the non-stomatal factors as major causes, resulting in photosynthesis rate and biomass decline. The effect of N input on photosynthesis being dependant on water supply provides a basis for regulation of N nutrition.

关 键 词：玉米 光合作用 光合速率 作物产量 叶绿素含量 生理特性 气孔导度 CO2浓度 自由水 叶肉细胞 

分 类 号：S513[农业科学—作物学] Q945[生物学—植物学]