UV-B对设施桃叶片光合功能及叶绿体超微结构的影响

对温室栽培的油桃中油5号(Prunus persica var. nectarina cv. ‘Zhongyou5’)适量补充UV-B, 分析其对桃叶片光合功能及叶绿体超微结构的影响。结果表明, UV-B处理下各色素含量均有不同程度的增加, 其中叶绿素b的含量和净光合速率(P_n)提升幅度较大。相较于未补充UV-B的桃树(对照), UV-B处理的F_v/F_m无显著变化, F_v'/F_m'比值、光化学猝灭系数(qP)、非光化学猝灭系数(qN)以及PSII实际光化学量子效率(Φ_PSII)均有显著或极显著升高。透射电镜结果显示, UV-B处理下叶绿体基质片层空隙小, 堆叠紧密, 叶绿体外膜边缘清晰。可见, 温室内适量补充UV-B可快速改善叶片叶绿体的超微结构, 提升叶绿素分子捕获光能及向PSII传递的能力, 增大PSII反应中心的开放程度, 提高实际光能转化效率和PSII电子传递量子效率, 提高叶片的光合功能。该研究为设施果树光合性能改善和UV-B合理利用提供了理论依据。

Effects of UV-B on Photosynthetic Function and Chloroplast Ultrastructure of Peach Leaves Grown in Greenhouse

After supplementing appropriate amount of UV-B to the nectarine (Prunus persica var. nectarine cv. ‘Zhong- you5’) cultivated in the greenhouse, we analyzed the effects of UV-B on photosynthesis and chloroplast ultrastructure of the Zhongyou5 leaves. We found that the content of leaf pigments was increased under UV-B treatment, particularly the content of chlorophyll b and the net photosynthetic rate (P_n) being greatly increased. Compared with the peach trees without UV-B supplementation (control), UV-B treatment did not affect the F_v/F_m ratio significantly. However, the F_v'/F_m' ratio, the photochemical quenching coefficient (qP), the non-photochemical quenching coefficient (qN), and PSII actual photochemical quantum efficiency (Φ_PSII) were all significantly improved. Transmission electron microscopy analysis also showed that under UV-B treatment, the chloroplast stroma lamellae had small voids and were tightly stacked, and the chloroplast outer membrane edge was clearer than those in control. These data suggest that appropriate UV-B supplement in the greenhouse can optimize the ultrastructure of leaf chloroplasts, thereby improving photosynthesis. Our study provides a theoretical basis for the improvement of photosynthetic performance of fruit trees by using proper UV-B irradiation in greenhouse.