Effect Of Fungicide With Chitosan And Heat Treatment On Diseases Of Post-harvest Melon Fruits

In this paper, the test materials were melon ‘Xi Zhou Mi No.17'. The test's objective is to search the effectively fungicides on melon Alternaria and Fusarium, and reducing the dose of fungicide, regulating the metabolism of melon in cold storage, controling diseases and chilling injury, so the melon can achieve the purpose of long-term preservation. Using L9(34) orthogonal test to select chitosan concentration, heat treatment temperature and types of fungicide, the test select a best method to combine different treatment to preserve melon fruits, and explore the effect of physiological and biochemical on combine treatment melon. The results of the effective control of melon fruit diseases and extended shelf time, improve the storage quality, delay senescence, provide a theoretical basis for the melon preservation technology. The research contents are as follows:1. Research on the single factor test for different concentrations of chitosan, different temperatures of heat treatment and different types of fungicides. The results showed that chitosan and heat treatment melon fruit could delay the firmness, soluble solids content, vitamin C content and peel chlorophyll content decreased during storage; Inhibition of the fruits weight loss and disease exponent increased in 36 days. The better concentrations of chitosan is 10 g/L, 15 g/L, 20 g/L. And the better temperatures is 50?, 55?, 60?. By using the cell growth inhibition assay, found that three kinds of fungicide including tebuconazole, prochloraz, pyraclostrobin has a strong bactericidal effect on Alternaria and Fusarium.2. By the result of single factor test, and use L9(34) orthogonal test with the index of good melon fruit, weight loss and the average relative conductivity as the evaluation standards. Compared the different quality between treatment and control group, the test select a best one of combined treatment on preservation of melon. The result showed that compared with control group, the best treatment is that temperature of water is 55? with prochloraz and Chitosan is 20 g/L, which could increase the good fruit, hardness, chlorophyll, total phenols, flavonoids during refrigeration, and delayed respiratory peak obviously.3. To research the combined treatment incluing Chitosan Heat treatment with Prochloraz on biochemical metabolism of Hami melon during storage which can get the reasons for improve the storage quality and reduce disease. After a combined treatment of 55? water and Prochloraz with Chitosan of 20 g/L, the melon has a significantly enhanced result. Not a improment on POD, PAL, CAT, SOD, ?-1.3-Glucose enzyme, the content of lignin on the early stage(0~18)d. But treatment group can effectively inhibit pathogens, delay the time of infection, and as fruit the infection of pathogens which a improment on POD, PAL, CAT, SOD, ?-1.3- Glucose enzyme, the content of lignin which creating a effect on pathogenic bacteria. Determination of 20 g/L chitosan, 55? heat water combined with prochloraz(0.667 g/L) treatment prochloraz residues by using HPLC. The results showed that melon fruits epidermis, inwardly melon epidermis 1~8 mm, 9~17 mm prochloraz residues content were: 0.843 mg/kg, 0.062 mg/kg, 0.037 mg/kg, far less than prochloraz in the skin inedible tropical and subtropical fruits maximum level of 7 mg/kg.4. Reaearch on Alternaria lesions inoculated test, observe the resistance performance of each treatment group to achieve the aim of optimizing the concentration of fungicides and the effect of compound treatment.With 20 g/L chitosan, water at 55? combining three kinds of heat treatment prochloraz concentration(0.333 g/L, 0.5 g/L, 0.667 g/L) for the combined treatment group; respectively water at 55?, 20 g/L chitosan coating, 0.667 g/L prochloraz and with 20? normal temperature water as control group. The results showed that 55? heat treatment, 20 g/L chitosan could induce resistance enzymes.In the first 5 d after inoculated Alternata, they could significantly improve melon fruit POD, CHT, GLU and lignin content. Depending on the antibacterial degree of each treatment group, each indicatored trends are different. For three combined treatment group, it has direct antibacterial ability. When the first 5 d after inoculation, the three combined treatment group POD, CHT, GLU enzyme resistance increased significantly, and second peak emergence at the 25 d. Intuitive indicators such as lesion diameter, depth and incidence rates begined to growth at 15 d, 20 d, the three combined treatment significantly inhibited the growth of Alternaria lesion, but the difference was not significant, choosed the lowest concentration of prochloraz treatment groups was 20 g/L chitosan, 55? heated water combined with prochloraz(0.333 g/L) treatment.