EFFECTS OF CALCIUM AND BORON ELEMENTS ON TOP ROT OF FRUIT PHYSIOLOGICAL DISEASES IN PERSIMMON (DIOSPYROS KAKI THUNB.)

Top rot is a newly discovered fruit disease in persimmon in recent years and is identified and confirmed to the physiological diseases of fruit. However, the cause of the disease is unclear. Some studies suggest that it is caused by the lack of calcium, but also others that it is caused by boron deficiency. ‘Gongcheng’ persimmon is used as the material in the test, which was designed for the treatments of different calcium fertilizers and different concentrations of peptide, to find the relationship between the occurrence of disease and calcium and boron. The results showed that the top rot of fruit in ‘Gongcheng’ persimmon begins in early September. The symptoms first appear as a small amount of the dark spots, and the flesh cork around the top and the waist of the fruit, followed by dark spots expanding gradually, and connected together so that the entire top of the fruit turns black, and the fruit completely loses its value. The effects of top rot of fruit on the different treatments, lime + peptide treatment is better, secondly, with the high activity of calcium fertilizer, compared with the control, the incidence rate of top rot was reduced by 18.87 and 15.67% respectively. In the two treatments, the calcium contents of diseased parts in the fruit were increased by 4.55 and 4.55% respectively, and the boron contents of that were increased by 9.90 and 28.86% respectively. The occurrence of top rot in persimmon fruit has a certain correlation with the content level of calcium and boron in the diseased parts, but the effect of calcium is greater that of boron element. Their deficiency may be one of the main factors that induce the occurrence of disease.