环割对柑橘叶片衰老的影响

以3年生红黎檬砧‘暗柳橙’（Anliucheng）为试材，研究了环割与环剥对柑橘叶片光合性能及活性氧代谢的影响。结果表明，环割和环剥30 d后均不同程度降低了叶片叶绿素相对含量（SPAD）、净光合速率（Pn）、蒸腾速率（Tr）、气孔导度（Gs）和细胞间CO2浓度（Ci），其中环剥处理对叶片SPAD和Pn产生了持续性的影响；环割和环剥在处理的前期均显著增加了叶片超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）等抗氧化酶活性；处理30 d后叶片抗氧化物质抗坏血酸（AsA）和还原型谷胱甘肽（GSH）含量显著低于对照，随后呈上升趋势，达到一个峰值后缓慢恢复到正常状态；各处理叶片膜脂过氧化产物丙二醛（MDA）含量均呈上升趋势，环割2次和环剥处理叶片初期MDA含量显著高于对照，引发柑橘叶片中一系列抗氧化反应，造成其膜脂氧化程度加剧。

Effects of Girdling on Senescence of Citrus Leaf

The 3-year-old‘Anliu’orange（Citrus sinensis Osbeck）grafted on Honglimeng（Citrus limonia Osbeck）was used as experimental material to study the effect of girdling on photosynthetic property and reactive oxygen metabolism of Citrus leaves. The results showed that ringing and sprial girdling decreased the chlorophyll relative content（SPAD），net photosynthetic rate（Pn），transpiration rate（Tr），stomatal conductance（Gs）and intercellular CO2 concentration（Ci）of leaves with different degrees after 30-day treatment. Girdling treatment had a long-term impact on leaf SPAD and Pn. The activities of antioxidant enzymes（SOD，POD and CAT）in leaves were improved after ringing and girdling. The antioxidant compounds（GSH and AsA）contents in leaves were significantly decreased at 30 d after treatment，then began rising to a peak and returned to a normal state slowly at last. The malondialdehyde （MDA）content was increased in all treatments，which was significantly increased compared with the control by ringing twice and girdling. These data showed that ringing and girdling in early stage affected photosynthetic metabolism of citrus leaves，and caused a series of antioxidation reaction and accumulation of reactive oxygen species in citrus leaves.