库源比改变对油橄榄产量及源叶光合作用的调节

【目的】研究油橄榄库源关系改变后源叶气体交换、叶绿素荧光特性和光合产物积累的长期响应特征及各项参数间的相互关系，以深化对果树库源关系改变中源叶光合作用调控机制的认识。【方法】以‘鄂植8号’油橄榄(Olea europaea L.)为试材，在初花期通过减源(摘叶)和缩库(疏花)措施处理，研究库源比改变对其产量和源叶气体交换、叶绿素荧光特性及光合产物积累的长期影响。【结果】摘叶处理显著降低了油橄榄果实重量及坐果率；疏花处理明显提高了果实重量，但对坐果率的影响不大。库源比降低后，短期内(处理后7 d)叶片中可溶性糖、淀粉和非结构性糖含量（NSC）显著增加；源叶净光合速率（Pn）、气孔导度（Gs）、蒸腾速率（E）显著下降，胞间CO₂浓度（Ci）显著升高，光系统Ⅱ(PSⅡ)最大光化学效率（Fv/Fm）明显下降，PSⅡ实际光化学量子效率（ΦPSⅡ）、光化学猝灭系数（qP）显著下降，非光化学猝灭系数（NPQ）显著升高。处理后30 d，3个处理间叶片中可溶性糖、淀粉含量差异消失，源叶气体交换参数Pn、Gs、E及叶绿素荧光参数ΦPSⅡ、NPQ的差异依然存在；处理后65 d，摘叶处理与对照之间大部分气体交换和叶绿素荧光参数的差异消失，但疏花处理与对照间Pn、Gs、E、Ci、ΦPSⅡ等参数的差异依然存在；处理后125 d，摘叶处理叶片中可溶性糖、淀粉和非结构性糖含量及大部分气体交换和叶绿素荧光参数均显著低于对照，而疏花处理ΦPSⅡ依然显著低于对照，Ci依然显著高于对照。库源比改变125 d后，Gs与Pn之间存在极显著正相关关系，E、Fm和ΦPSII与Pn之间存在显著正相关关系，而Ci、NSC与Pn之间无显著相关关系。【结论】库源比降低后源叶Pn的下降不能只归结于光合产物的直接反馈抑制，PSⅡ实际光化学量子效率下降可能是长期响应过程中Pn下降的主要原因。减源处理能在短期内提高油橄榄叶片光合能力，但会加速叶片的衰老。

Response of Yield and Leaf Photosynthesis to Sink-Source Ratio Altering Demand in Olive

【Objective】In order to more clearly understand the mechanism of source leaf photosynthesis response to sink-source ratio alteration, the gas exchange rates, chlorophyll a fluorescence kinetics and leaf carbohydrate content in a long-term (125 days after treatment) response to sink-source ratio alteration and their relationships in olive were investigated.【Method】Long-term response of gas exchange, chlorophyll a fluorescence and leaf carbohydrate was measured by using flowers removal and partial defoliation techniques at pre-flowering stages on two years old shoots of ‘Ezhi 8’ olive (Olea europaea L.) trees.【Result】The results showed that defoliation significantly reduced fruit weight and fruit setting, and flowers removal only significantly increased fruit fresh weight. In a short term (7 days after treatment) after source sink ratio decreased, soluble sugar, starch and non-structural carbohydrate content in leaves increased significantly, the source leaves net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (E) decreased significantly, the intercellular CO₂ concentration increased significantly, PSII maximum photochemistry efficiency (F_v/F_m) decreased dramatically, PSII photochemistry efficiency(ΦPSⅡ), photochemical quenching coefficient (qP) decreased significantly, non photochemical quenching coefficient (NPQ) increased significantly. Thirty days after treatment, there was no significant difference in the contents of soluble sugar, starch and non-structural carbohydrate among three treatments, while it was still exist difference of Pn, Gs, E, ΦPSⅡand NPQ among those. Sixty days after treatment, difference in most parameters of gas exchange and chlorophyll fluorescence between control and defoliation treatment was eliminated, but Pn, Gs, E, Ciand ΦPSⅡ in flowers removal treatment were also significantly different from the controls ones. One hundred and twenty-five days after treatment, soluble sugar and starch content and most parameters of gas exchange and chlorophyll fluorescence in defoliation treatment significantly decreased, however, ΦPSⅡin flowers removal treatment was also significantly lower than the control, Ciwas also significantly higher than the control. In a 125-day period after treatment, there was a significant positive correlation between Gs and Pn (P＜0.01), between E, F_m, ΦPSII and Pn (P＜0.05), and there was no significant correlation between Ci, NSC and Pn.【Conclusion】In the long-term response of gas exchange, chlorophyll a fluorescence and leaf carbohydrate to sink-source ratio alteration,PSII photochemistry efficiency (ΦPSⅡ) may be the main reason for the decrease of Pn, rather than the result of feedback inhibition of leaf carbohydrate accumulation. Defoliation can improve olive leaf photosynthetic capacity in a short term, but it will accelerate leaf senescence.