芒果对氟的吸收与果实生理病害的关系

Fluorine Uptake by Fruit and Leaf in Relation to Fruit Disorders in Mango

研究了芒果果实及叶片对大气氟的吸收与分布，监测了黑顶病及小果病发病果园雨水中氟的浓度变化。结果表明，氟由果皮气孔进入果实，随果皮蜡质增厚吸收量减少。叶片吸收的氟可部分转运到果实。果皮中氟浓度高于果肉和种子。果实内氟积累到一定程度可抑制细胞膨大生长，表现为“小果病”。溶解于雨水中的氟是黑顶病发生的直接原因，含氟雨水积聚果顶，氟渗入组织，引起坏死变黑。在田间将果实倒挂则症状出现在果肩。叶片比果实，老叶比新叶对氟伤害的抗性较强。整个生长过程叶片都吸收氟，叶尖叶缘含氟最高，伤害症状为叶尖叶缘干枯。

The uptake and distribution of atmospheric fluorine by/in mango ( Mangifera indica L. ) fruit and leaf were studied. The F content of the precipitation in one affected orchard where black tip and stunted fruit disorders appeared was monitored continuously. The results showed that F was absorbed by fruit through stomata on the fruit skin throughout the growth season. As the wax on the skin got thick,the absorption decreased. A small portion of F absorbed by leaf could be translocated to the fruit. Fluorine allocated mainly in the fruit skin rather than in the flesh and seed. F taken up by fruit at the early stage inhibited cell expansion causing stunted growth in the fruit as so called “stunted fruit disorder”. F containing raindrop gathering a the stylar end was the reason why an injurious symptom appeared exclusively at this part of the fruit as so called“black tip disorder”. F in the raindrops invaded into the tissue and caused necrosis. A field experiment with fruits deliberately hung upside down succeeded in moving the symptom to fruit shoulders. Mango fruit was much less resistant to F pollution than the leaf,whereas young leaves were susceptible to F toxicity than older ones. Leaves absorbed F throughout the whole growth stage. Leaf edges contained the highest F content. The symptom of F injury on the leaf began with necrosis at the leaf edge.