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作 者 ：孙谷畴 赵平 曾小平 彭少麟

期 刊 ：植物学通报 2000年 17卷 05期 页码：450-456

关键词：香蕉；UV-B辐射；光合速率；叶氮分配；

摘 要 ：补增UV－B辐射的香蕉叶片光下呼吸速率（Rd））和不包括光下呼吸的CO2补偿点（г*），分别为0.33μmol·m-2·s-1和46.5μl·L-1，较对照植株分别高5.6％和10.0％。在较高CO2浓度（>340μl·L-1）条件下的An/θp关系最初直线部分斜率，即表观量子产率(α-A)为0.023±0.007，而补增UV-B辐射处理的植株则降低13.0％，光能转换效率（δ）亦降低28.6％，表明UV-B辐射明显降低αA和δ。在高θp（1100μmol·m-2·s-1）和Ci<200μl·L-1条件下，对照植株的An/Ci关系为An=0.028Ci+1.44，补增UV-B辐射处理的植株则为An=0.021Ci+1.01，UV-B辐射降低羧化限制速率。最大羧化速率（Vcmax）和电子传导速率的光饱和值（Jmax）亦较低，补增UV-B辐射的叶片，叶氮在Rubisco的分配系数（PR）和叶氮在生物力能学组分的分配系数（PB）分别较对照低8.1％和3.0％，叶氮分配到类囊体膜捕光色素蛋白组分的则略见增高，UV-B辐射降低叶氮在光合循环组分的分配。

Abstract:Respiration rate in light (Rd) and the CO2 compensation point in absence of Rd (г*） were 0.33μmol·m-2·s-1 and 46.5μl·L-1 in leaves of Musa paradisiaca exposed to UVB radiation (4.8μW·cm-2) respectivty. They were higher than those in control plants by 5.6% and 10%, respectively. The initial slope of lightresponse curves, the apparent quantum yield (αA) in leaves of control plants was 0.023±0.007 while the relative value was decreased by 13.0% in plants exposed to UVB radiation. A parameter related to the efficiency of light energy conversion (δ) was also decreased by 28.6% for plants exposed to UVB radiation in comparison with that of control plant. The partial An/Ci curves measured under θp 1100μmol·m-2·s-1, was An=0.028Ci+1.41 for leaves of control plants and An=0.021Ci+1.01 for leaves exposed to UVB radiation. Maximum carboxylation rate (Vcmax) and electron transport rate in saturated θp in leaves exposed to UVB treatment were also lower than those of controls considerably. The partitioning coefficients for leaf nitrogen in Rubisco (PR) and in bioenergetic (PB) in leaves exposed to UVB radiation were lower than those of controls by 8.1% and 3.0%, respectively. And the fraction of leaf nitrogen in thylakoid lightharvesting component (PL) increased finely in plant exposed to UVB radiation as compared to that of controls. The results imply that supplementary UV-B radiation cause the decrease of nitrogen partition in the components of photosynthetic carbon cycle and decrease photosynthetic rate.

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