Biological Effects Of Pulsed Magnetic Field On Bursaphelenchus Xylophilus And Botryosphaeria Dothidea

The characteristics of pine wilt disease and tree's canker were such as incidence of short, easy to spread, with a hidden, difficult to control, which cause a serious threat of environment, forest resources and afforestation. At present, the failure to screen out environmentally and efficient control methods. Therefore, this study based on Pulsed magnetic field(PMF),Pine wood nematode(PWN) and Botryosphaeria dothidea(BD)as research subjects. Studying on PMF that how to have an effect on the behavior physiology, biochemistry, ultrastructure of PWN, as well as the growth and infection of BD.The results were as follows:(1)The wider pulse rise time, the longer treatment time and the shorter pulse period were greater affect the PWN; with the treatment time longer, the inhibitory activity of PWN was more significant, and the recovery time required was longer during 5ms and 10ms of pulse rise time; after PMF treatment, 3, 4-instar larvae and female had a stronger resistance, they still had a good ability of migration, but 2-instar larvae and male were significant inhibited, and only a few move out; in the 1ms of pulse rise and treatment less than 20 min, there is little impact on the reproduction of PWN.(2) 4th instar and females had a strong resistance of the PMF; with Pulse rise time 10ms and the treatment of 60min, PWN corrected mortality was 100%. After the PMF treatment, the cellulase activity of PWN increased within a short time, and with the longer treatment time, the lower cellulase activity was. Wider pulse and longer treatment time were can strengthen the inhibion of the survival, cellulase activity and reproduction of PWN. The observations with scanning electron micrograph (SEM) revealed that there is no significant change in morphology of PWN, but qualitative showed that the quantity of rod-shaped bacteria reduced that carried by PWN.(3) Based on PMF, the effect of different treating time on the growth and infestation of BD was researched under the condition of fixed pulse rise time 10ms. The results showed that short PMF treatment can effectively inhibit growth and infestation BD and the longer time treatment , the stronger the inhibition. With pulse for 45min treatment, colony inhibition was 54.11% after 48h, and the browning index of populus callus inoculation after 72h was only 26.89%; With pulse for 60min treatment, the inhibitory effect was best, and the colony all was dead. The observations with SEM revealed that the colony has the characteristics of uneven thickness, the adhesions mycelium, the surface wrinkled, branch of parts of, even dryness of hyphal. Based on TEM, after PMF treatment, the cell wall was thinner significantly and the inner parts disordered and degraded, moreover the cell structure was destroyed seriously and intracellular vacuoles increased. Because of BD callus cells structure was influenced on different degrees of damage with deformation and disintegration of cell wall, decomposition of the layer, fracture of Plasma membrane, plasmolysis; Cell organelles decomposed and deposited near cell walls, degradation of intracellular hyphae and cavum. The PMF has a strong inhibitory effect on the growth and infestation of BD and can change the mycelium ultrastructure.