绿斑病藻寄生对夏橙光合日变化的影响

Effect of Green Spot Disease (Apatococcus lobatus) Parasitization on Diurnal Variation of Photosynthesis of Valencia Orange Trees

以盆栽的2年生‘奥灵达’夏橙为试材,用LI-6400型便携式光合测定系统研究了绿斑病藻寄生的夏橙叶片光合日变化规律。结果表明:轻度病叶(严重度为5%)净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)和胞间CO2浓度(Ci)的日变化与健康叶片相似,Pn和Gs日变化呈双峰型曲线,Tr日变化呈单峰型曲线,Ci在午前直线下降,午后维持一段时间的较低水平,而后逐渐回升,光合作用有明显的“午休”现象,主要受气孔因素控制;中度病叶(严重度为40%)和重度病叶(严重度为80%)的光合日变化与健康叶片明显不同,Pn、Gs和Tr的日变化曲线整体大幅度下降,变幅和峰值均小,而Ci在午前下降缓慢,午后一直保持较高水平,光合作用主要受非气孔因素控制。

The effect of green spot disease （Apatococcus lobatus） parasitization on diurnal variation of photosynthesis of valencia orange trees （ Citrus ‘Olinda＇ ） was studied by portable photosynthesis system LI-6400 with 2-year pot-grown grafting seedlings. The results showed that diurnal course in net photosynthetic rate （Pn） and stomatal conductance （Gs） of leaves with low severity （5 % ） presented two peaks, transpiration rate （Tr） appeared single peak, intercellular CO2 concentration （Ci） before noon greatly declined and lower Ci was kept afternoon. Leaves with slight severity were similar to healthy leaves in diurnal variation of photosynthesis, their photosynthesis appeared ‘Wuxiu＇ phenomenon, and mainly controlled by stomatal factors. Diurnal changes in photosynthesis of leaves with medium severity （40%） and high severity （80%） were different greatly from the healthy leaves, their diurnal curve of Pn, Gs, and Tr declined sharply, Ci decreased slowly before noon and higher Ci was maintained in the whole afternoon, their photosynthesis was mainly controlled by non-stomatal factors.