Researching The Effects Of Different Soil Disinfection Methods On The Continuous Cropping Obstacle Of Watermelon In Plastic Shed

Watermelon is one of the important economic crops in our country,but the continuous cropping obstacle seriously affects the sustainable development of watermelon production.Therefore,solving continuous cropping obstacle has great practical significance,undoubtedly.This experiment,of which take continuous land of watermelons for 6 to 7 years as research object,‘nongkeda 5'as experimental material,studied effects of different soil disinfection treatments on watermelon growth and fusarium wilt,and explored the inhibition effects of different soil disinfection treatments on watermelon continuous cropping obstacle by analyzing soil biological characters,physical and chemical properties,and the growth of fusarium oxysporum.The main results are as follows.1.High temperature and stuffy shed combined with soil disinfection significantly increased the air temperature and earth temperature of 10 cm.The maximum air temperatures in 2016 and 2017 were reached 57.82oC and 61.02oC,respectively,which were 19.28oC and14.38oC higher than control respectively.Moreover,the maximum earth temperatures in2016 and 2017 were reached 48.3oC and 50.12oC,respectively,which were 11.2oC and 7.95oC higher than control respectively.High temperature and stuffy shed combined with soil disinfection increased the number of actinomycetes,reduced the number of fungi,meanwhile,increase the ratio of bacterial and fungal community.Compared with control,lime+ammonium hydrogen carbonate made the number of fungi reduced by 43.80%-55.29%,flooding made it reduced by 53.59%,metham made it reduced by 35.27%-51.86%,and ammonium hydrogen carbonate made it reduced by 22.66%-44.04%.With respect to the ratio of bacteria,fungi and actinomycetes accounted for the total microbial biomass,the bacteria was the highest proportion in soil,followed by actinomycetes;while fungi was the smallest proportion in soil,only accounting for 2.17%~10.75%of total microbial biomass.2.High temperature and stuffy shed combined with soil disinfection reduced the blight disease incidence.Compared with control,the combination treatment of lime and ammonium hydrogen carbonate,ammonium hydrogen carbonate treatment and metham treatment made the blight disease incidence reduced by 42.24%-47.92%,4.89%-50.53%and 1.51%-16.27%,respectively;while the incidences of metham 12.5 kg/667 m~2and the combination of lime 10kg/667 m~2and ammonium hydrogen carbonate 100 kg/667 m~2were 69.03%and 45.27%higher than control respectively.3.High temperature and stuffy shed combined with soil disinfection affected the fruit quality of watermelon.Total soluble sugar was significantly higher than control,and metham was 8.55%-184.94%,flooding treatment 112.12%,lime+ammonium hydrogen carbonate240.57%-274.87%,ammonium hydrogen carbonate 96.23%-420.11%.The reducing sugar of four treatments were also increased,that of metham,flooding treatment,lime+ammonium hydrogen carbonate,ammonium hydrogen carbonate were 110.61%-331.58%,171.75%,32.29%-100.80%,5.88%-238.01%,respectively.The soluble protein contents of metham and flooding treatment were higher than control,and were 31.67%-56.67%and 63.19%,respectively.Comprehensive analysis,the improvement of four treatments to fruit quality of watermelon were,from high to low,lime+ammonium hydrogen carbonate,ammonium hydrogen carbonate,metham and flooding.4.High temperature and stuffy shed combined with soil disinfection affected the fruit quality of watermelon soil physical and chemical properties.Compared with control,soil available nitrogen,phosphorus and kalium contents of ammonium hydrogen carbonate were increased by 37.51%-79.22%,13.13%-30.67%and 10.03%-31.44%,respectively,and the available N and K of lime+ammonium hydrogen carbonate increased by 26.78%-97.37%,9.77%-22.18%.These results indicated that ammonium hydrogen carbonate and lime+ammonium hydrogen carbonate effectively promoted the release of soil nutrients and improved the fertility of continuous cropping soil.5.The culture medium with different soil disinfectant affected the growth of fusarium oxysporum.For R0,the inhibition effects of metham,lime+ammonium hydrogen carbonate,ammonium hydrogen carbonate and chlorine dioxide were 50.20-100%,1.96-61.96%,2.35-21.56%and 0-23.14%,respectively.For R1,the inhibition effects of metham,lime+ammonium hydrogen carbonate,ammonium hydrogen carbonate and chlorine dioxide were 81.56-100%,15.68-41.96%,1.96-4.71%and 0.79-7.06%,respectively.For R2,the inhibition effects of metham,lime+ammonium hydrogen carbonate,ammonium hydrogen carbonate and chlorine dioxide were 71.38-100%,1.96-16.86%,0-12.15%and 0-0.79%,respectively.Comprehensive analysis,the inhibition effect of four treatments to the growth of fusarium oxysporum were,from strong to weak,metham,lime+ammonium hydrogen carbonate,ammonium hydrogen carbonate and chlorine dioxide.