Mango (mangifera Indica L.) Fruit Physiological Disease And Its Causes

The present studies were concentrated on the causes of three main physiological disorders of mango fruits, i.e., black tip, stunted fruit and internal flesh breakdown, in Guangdong. The results obtained were as follows.1. The visible symptom of black tip disorder was the darkening at the fruit stylar end. Vascular bundles of the cut pedicels secreted no milky sap when the fruit was picked before harvest. Fluoride was the direct cause of black tip disorder. Dipping fruits in fluoride solution showed that the range of fluorine concentrations which caused the disorder was about 150-600 mg kg-1. Fluorides were from the brick kilns and other factories in the vicinities of the mango orchards. Fluorine-containing rain drops gathered at the stylar end of the hanging fruit and the fluorine penetrated into the tissues caused damage to fruit. This was why the disorder symptom appeared only at the stylar end.2. The typical symptom of stunted fruit disorder was the fruit which remained small in size even at harvest. A HF fumigation cabinet experiment confirmed that the gaseous fluorine in the atmosphere was the direct cause of the stunted fruit disorder. Fluoride penetrated into tissues through stomata on the surface of peel at a considerably early stage of ontogeny and inhibited fruit growth. Although results from microscopic observations on flesh tissues showed completion of cell division in the...