Studies On The Effects Of High-voltage Pulse Current On The Important Biological Factors Of Pine Wilt Disease

The effects and the important factors of high-voltage pulse current on pine woodnematode, Monochamus alternatus and Pinus massoniana, and the possibility and effect ofhigh-voltage pulse current on prevnting pine wood nematode invasing and curing Pinusmassoniana inoculated with pine wood nematode were investigated. The main conclusionswere summarized as following:(1) The result of the effect of high-voltage pulse current on the survival, vitality andreproduction of pine wood nematode with aseptic water as medium showed that high-voltagepulse current could kill pine wood nematode and the main impact factors were the pulse widthand electric treatment time. The wider the pulse width and the shorter electric treatmentinterval and the more numbers pulse and the longer treating time, the better killing effect ofhigh-voltage pulse current on pine wood nematode. The influence of pulse interval on theresults was relatively small and it could be set at a constant point 28ms. Pine wood nematodewas killed and inhibiting efficiently by the treatment of pulse width 2ms (electric current0.025±0.001A), pulse interval 28ms, electric treatment interval 1min and pulse number 32treating more than 690min. The treatment of pulse width 1ms (electric current 0. 017±0.001A)and 0.5ms (electric current 0.013±0.001 A) had llittle effect on killing Pine wood nematode.High-voltage pulse current could inhibit the reproduction capacity of pine wood nematode. Thewider the pulse width and the longer treating time, the better inhibiting effect of high-voltagepulse current on pine wood nematode.The research of the effect of high-voltage pulse currenton the migration of pine wood nematode with black pine branch as medium showed thathigh-voltage pulse current could inhibit the migration and diffusion capacity of pine woodnematode and the main impact factor was electric treatment interval. The reaction of differentinstars of pine wood nematode to high-voltage pulse current were different, the adult was moreresistant to high-voltage pulse current than the larvae, especially the female and the larvae wasmore sensitive, specially the 2nd instar.(2) The result of the effect of high-voltage pulse current on the 4th instar larvae ofMonochamus alternatus showed that the body weight decreased rapidly and the larvae wouldbe death later; the larvae developed into the malformed pupae and died; causing a prolonged larval period, and delayed pupation, even permanently staying in larval stage and could notpupate. The wider the pulse width and the longer treating time, the better killing and inhibitingthe growth development effects of high-voltage pulse current on Monochamus alternatus.(3) The result of the effect of high-voltage pulse current on callus of Pinus massonianaestimated by the relative electrolyte leakage showed that callus of Pinus massoniana hadresistance to high-voltage pulse current. The change of the relative electrolyte leakage of callusof Pinus massoniana treated by pulse width 3ms (electric current 0.032±0.0015A) and pulsewidth 1ms (electric current 0.017±0.001A) in 400min were accord with that of withouthigh-voltage pulse current treatment and the cell membrane could keep stability. The influenceof high-voltage pulse current on cambium and xylem of the host pine estimated by the tissuebrowning method was studied. The result of the black pine branch showed that the morenumbers of pulse and the wider the pulse width and the shorter electric treatment interval, themore and the severer the damage. The experiment showed that high-voltage pulse current hadno effect on the color of cambium and xylem, stem capacitance and impedance, exudation andmoisture physiology of Pinus massoniana, even could increase the relative water content ofneedle and branch and stimulate breast-height diameter continual growth in some extent.(4) The effect of high-voltage pulse current on Pinus massoniana inoculated with pinewood nematode was investigated. The result showed that the appearing time of the symptomwas postponed; the development of the disease was delayed. The tend of the reaction of therelative water content of branch to the pathogenesis was similar to that of needle, but theinfluence degree of relative water content of branch is serious than that of needle. The relativewater content of branch and needle and the transpiration of Pinus massoniana could maintainto a certain level for longer time with electric treatment. The breast-height diameter increasedin some extent during the period of electric treatment. As the disease was serious, the stemcapacitance and impedance rose and decreased. According to the results the good electrictreatment is pulse width 3ms (electric current 0.03-0.004A), the electric treatment interval5min, pulse interval 28ms, and pulse number 32.