遮荫和全光下生长的棉花光合作用和叶绿素荧光特征  

PHOTOSYNTHETIC CHARACTERISTICS AND CHLOROPHYLL FLUORESCENCE IN LEAVES OF COTTON PLANTS GROWN IN FULL LIGHT AND 40% SUNLIGHT

作　　者：杨兴洪[1] 邹琦[1] 赵世杰[1] 

机构地区：[1]山东农业大学生命科学学院

出　　处：《植物生态学报》2005年第1期8-15,共8页Chinese Journal of Plant Ecology

基　　金：国家重点基础研究规划项目(G1998010100)

摘　　要：遮荫条件下(遮荫下光强相当于自然光强的40％左右)棉花(Gossypium hirsutum)叶片光合速率明显降低, 仅为自然光强下生长叶片的30％-40％,叶片中RuBP羧化酶活性降低,而表观量子效率(AQY)较高。不同光照条 件下生长的棉花叶片对短时间持续光强的光合诱导过程有明显的差异,由弱光转到强光下,自然光强下生长的叶 片的Pn、Gs、φPsⅡ及非光化学猝灭系数(NPQ)都能在较短的时间内达到最大值,而遮荫叶片需要的时间较长;遮 荫下生长的棉花叶片的实际光化学效率,随光强的增加下降幅度较大,而自然光照下生长的叶片下降幅度较小;自 然光照下生长的叶片的NPQ随光强的升高达到较高水平,而遮荫叶片在较低的光强下即达到最大值,此时NPQ 较低,遮荫叶片依赖于叶黄素循环的能量耗散水平较低。遮荫叶片较低的光合速率以及过剩光能耗散能力是其转 入自然强光后光抑制严重的主要原因。Depending on the amount of light available during growth, plants possess the ability to react to the amount of available light during growth using two distinct growth-responses: the strong-light growth-response as found at high light quanta and the weak-light growth-response, which is seen in shade leaves and plants growing under low-light. This ability of plants and chloroplasts to adapt to light is a fundamental growth-response, which is associated with specific changes in the morphology, physiology, biochemistry and structure of leaves and chloroplants. In wheat-cotton intercropping systems, cotton seedlings are shaded by wheat plants for about 40-45 days and then exposed to direct sunlight and high ambient temperatures and low humidity immediately after wheat plants are harvested. The growth of cotton plants declines for about 20 days following this high light exposure and then gradually acclimate, but the squaring and inflorescence period are delayed. In this study, the effects of shading (40% of natural light intensity) on photosynthesis and chlorofluorescence characteristics of cotton leaves were examined using chlorophyll fluorescence and gas exchange techniques. Compared with cotton seedlings grown in full sunlight, a lower photosynthetic rate, lower PSⅡactivity and lower efficiency of primary energy conversion as well as lower electron transport rate were found in plants grown under shaded conditions (40% sunlight). Light saturation point (LSP), light compensation point (LCP), CO2 saturation point (CSP) and CO2 compensation point (г) also were higher in leaves grown in full sunlight than under 40% sunlight. Upon sudden exposure from low to high photon flux density (PFD), the net photosynthetic rate (Pn), stomatal conductance (Gs) , actual PSII efficiency (φPSⅡ) and non-photochemical quenching (NPQ) of full light leaves increased to maximal levels in a short period, whereas it took a much longer time for those of shaded leaves to reach maximal levels. The shaded cotton leaves were more susceptible

关 键 词：遮荫条件 自然光照 棉花 光合作用 叶绿素荧光 光抑制 

分 类 号：S562[农业科学—作物学]