Litchi downy blight (Peronophythora Litchi Chen ex Lo) is one of the most important preharvest and postharvest diseases of Litchi. The effect of temperature, pH, light, carbon source and moisture on the mycelia growth, sporulation and sporangia germination of litchi downy blight was primarily studied. For the mycelial growth of the pathogen of the litchi downy blight, the range of temperatures was 12-32℃, the optimum being 28-30℃, and the range of pH was 3-10, the optimum being 6-8. For the sporulation, the range of temperatures was 12-32℃, the optimum being 26-30℃, and the range of pH was 3-10, the optimum being 5-6. For the sporangium germination, the range of temperature was 10-34℃, the optimum being 20～26℃，and the range of pH value was 3-10, the optimum being 5-6. The treatment of darkness with fluorescent or alternative fluorescent light did not have significant effect on the mycelial growth, sporulation or sporangium germination. Only in free water, the sporangium was able to germinate. The starch, sucrose, glucose and maltose could promote the mycelial growth.

Lychees (cv. Huaizhi, Nuomici, Guiwei) were stored for over 30 days at temperature 4℃, then the superoxide dismutase (SOD) activity, membrane permeability, superoxide radical and Malon-dialdehyde (MDA) content in the pericarp were determined, and the browning index of the pericarp was also investigated. The results showed that the browning index and membrane permeability were greatly increased with the extension of storage; SOD appeared to decline at first, then raise, and at last descend with the extension of storage. In contrast, Malon-dialdehyde (MDA) content and superoxide radical producing rate changed regularly, that is to say, they raised first, then declined and at last raised again with the extension of storage and browning. MDA and superoxide radical had positive correlation with the browning; however SOD activities had a negative correlation with the browning of Lychee pericarp. Furthermore, SOD activity has a certain adverse trend with MDA content and superoxide radical producing rate. These indicated that SOD, MDA, superoxide radical and plasama membrane permeability could be considered as important indices in determining the browning of Lychee pericarp.

The effect of latent infection of anthracnose fungus on postharvest physiology of litchi fruits and the environmental conditions on growth of pathogenic fungus(Colletotrichum gloeosporioides Penz.) were studied. The results showed that respiration rate, ethylene production and malondialdehyde (MDA) content of the fruits latently infected by anthracnose fungus were evidently increased. the mycelial growth, sporulation and conidial germination of litchi anthracnose fungus was primarily studied. For the mycelial growth of Colletotrichum gloeosporioides the range of temperature was 8℃-38℃, the optimum being 28℃-32℃, and the range of pH was 3-10, the optimum being 5-6. For the sporulation, the range of temperature was 12-36℃, the optimum being 28℃-32℃, and the range of pH was 3-10, the optimum being 3-4. For the conidial germination, the range of temperature was 8-38℃, the optimum being 28-32℃, and the range of pH was 3-10, the optimum being 6-7. When relative humidity reached 100% or in water, the percentage of conidial germination was highest. The lethal temperature for the spores was 50℃ remaining 10 minutes, while the lethal temperature for the mycelium was 60℃ remaining 30 minutes.