【作者】 张自坤；

【导师】 曹辰兴；

【作者基本信息】 山东农业大学 ， 蔬菜学， 2005， 硕士

【摘要】 本试验研究了黄瓜留种过程中叶片的光合特性、光化学效率及1,5–二磷酸核酮糖羧化酶活性的变化、种子发育后期单个叶片衰老相关生理生化变化,并对种子发育后期光合电子传递途径的改变、叶绿素降解及光系统II 中心失活的积极意义进行了探讨。主要结果如下:1.黄瓜种株在种子发育前功能叶片光合速率日变化呈双峰曲线,光合速率最高峰分别出现在10:00 和14:00;在黄瓜种子发育后期,功能叶片光合速率Pn 在中午时没有下降,而是随着光强的增加而增加,午后随光照强度的降低而下降,光合速率日变化为单峰曲线型,光合速率最高值出现在12:00。2.在种子发育后期,随着黄瓜种株叶片的衰老,叶片捕获的光能用于光合碳同化的能量比例愈来愈少,而被热耗散和其它途径消耗的电子逐渐增多,AQY 随衰老程度的加重而降低。Fv/Fm 与ΦPSII在一天中随光照强度的增加而下降,在中午时达到最低值,在下午光照强度减弱时,得到完全恢复。在叶片衰老过程中,ΦPSII 逐渐降低,而Fv/Fm 基本保持稳定。随着生育期的进行,qP 逐渐降低,而qN 逐渐升高。前期PSII 电子传递活性最大,而以热的形式耗散掉的光能比例很小。3.叶绿素含量的下降与光合速率的下降不一致。光合速率达到高峰后立即下降,而叶绿素达到高峰后会持续一段时间才开始下降,说明在种子发育过程中,叶绿素下降不是光合速率下降的原因,而是与光合机构其它组分一起降解的伴随过程。叶绿体色素的降解和PSII 反应中心失活是一种适应机制。更多还原

【Abstract】 Characteristics of photosynthesis, changes of photochemical efficiencyand RuBPCase activity, changes of physiology and biochemistry of thedifferent leaves in cucumber plant during seed development were studied.Meanwhile the change of electron transpiration, the positive function ofchlorophyll decomposition and inactive of PSII reaction center during seeddevelopment were discussed. The results were as follows:1. The diurnal changes of net photosynthetic rate were different indifferent stages. The curve of diurnal change of net photosynthetic rate has twopeaks, one peak is at 10:00, and the other at 14:00, having an obvious middydepression in prophase of seed development, whereas only has a peak at 12:00in anaphase seed development.2. With the development of seed, the amount of photons that were usedfor carbon assimilation was decreasing, while the amount of photons used forheat dissipation and other dissipative ways was increasing. So the apparentquantum yield (AQY) was decreasing, the photochemical fluorescencequenching was also decreasing, but the nonphotochemical fluorescencequenching was increasing with the development of seed.Maximal PSIIefficiency (Fv/Fm) and actual photochemical efficiency ofPSII(ΦPSII) were decreasing with the illumination intensity enhanced, havingits lowest value at noon, but the Fv/Fm and ΦPSⅡcan recover with theillumination intensity weakened, so we can conclude that the photosyntheticreaction center was not destroyed at noon. 3. The change of chlorophyll content and net photosynthetic rate wasdifferent. When Pn came to its peak, it decreased immediately, but chlorophyllcan keep about a week after its peak. So the decrease of chlorophyll content isnot the cause of the decrease of Pn, it was concomitance of the other elementsof photosynthetic organ decomposed. The decomposition of chlorophyll andinactive of PSII were a protective and adaptive mechanism during seeddevelopment. 4. The change of Ribulose bisphosphate carboxylic enzyme (RuBPCase)activiey is similar to the change of Pn, it increased first, and then declined. TheRuBPCase activity of 10th leaf come to its peak 7 days after blossoms, andthen decreased obviously. The decrease of Pn started 14 days after blossom.The decrease of RuBPCase activity was earlier than the decrease of Pn andchlorophyll content. Meanwhile the decrease of RuBPCase caused thecarboxylation efficiency (CE) declined. So the main reason of decrease of Pnwas the decrease of RuBPCase activity. 5. In different leaves of the cucumber plant, the chlorophyll content, Hillreaction activities, soluble protein contents and SOD、POD、CAT activitiesincreased first and then declined, while insoluble protein contents kept steady,and the MDA contents increased continually with lowering of leaf position. The decomposition of soluble protein was earlier than the decrease of Hillactivities, Pn, and chlorophyll content during seed development. With thedevelopment of seed development, the SOD, POD, CAT, activities increasedfirst and then declined. The decline of SOD activities was earlier than PODand CAT, the decrease of SOD cause the MDA content increasingcontinuously.更多还原