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【答案】应助回帖
125254927(金币+200, 翻译EPI+1): 非常感谢，希望有机会和你学习！ 2011-11-04 13:51:51
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Under natural conditions on a sunny day ，using flatten young leaves of cotton(young leaves) and fully grown leaves (mature leaves) for the study. By measuring leaf gas exchange parameters and fluorescence parameters of chlorophyll a in different developmental stages , and Conducting rapid light response curve fitting on leaves of different developmental stages by using Dual-PAM100 , compared the difference of photosynthetic and chlorophyll fluorescence characteristics of young leaves and mature leaves ,revealing the coordinate mechanism between photoinhibition and light protection mechanism of young leaf under High light intensity .The results showed that there are significant difference of photosynthesis and fluorescence characteristics between young leaves and mature leaves.Compared with mature leaves, young leaves have lower photosynthetic capacity, lower chlorophyll (Chl) content ,stomatal conductance (Gs) is the cause of lower Pn (carbon assimilation rate) ,therefore, the intercellular CO2 (Ci) is higher , optical system Ⅱ (PS Ⅱ) , actual photochemical efficiency (ΦPS Ⅱ) and photochemical quenching (qP) were lower. Below 1800 (μmol.m-2.s-1) , the higher CEF is one of the reasons of higher photosynthetic capacity of mature leaves . In the same light intensity, low light saturation point (LSP) of the young leaves are more susceptible to photoinhibition, But the magnitude of diurnal variation of its primary photochemical efficiency of PS Ⅱ (Fv / Fm) is significantly less than that of mature leaves. The results show that leaves effectively dissipate the excess energy through the carotenoid (Car), photorespiration (Pr), non-photochemical quenching (NPQ) .Above 1800 (μmol.m-2.s-1) ,young leaves of the PSI-CEF rapidly rise in the moment, which indicates that at high light intensity CEF may play a protective role of light . |
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