Effects of soil application with calcium oxide on control of Fusarium wilt of watermelon and its preliminary mechanism research

In this study,five concentrations of soil calcium disinfection were used to evaluate the effects of calcium oxide on watermelon Fusarium wilt by the dynamic change of soil pH,the amount of Fusarium oxysporum f.sp.niveurn in soil,the incidence of Fusarium wilt and plant growth.The results showed that,when the soil was applied with calcium oxide,the incidence of plant disease was significantly decreased,and the relative control rates of each treatment were 14％,57.8％,96.3％,94.7％,and 94.7％,respectively.All treatments had the effect of promoting plant growth and development after 10 days of colonization,among which 1.34 g/kg treatment was the most significant.With the increase of calcium oxide application rate,the soil pH also increased and tended to be stable in 30 days.The research of F.oxysporum f.sp.niveum number showed that the number of pathogens in treated soils showed a significant decrease.PDA flat test results showed that,when calcium ion concentration was higher than 80 mmol/L,the growth of the pathogen and quantity of spore production began to be suppressed,and with the increase of concentration,thc inhibition strengthened.Therefore,the application of calcium oxide in the soil could not only improve the soil acidification,but also effectively control watermelon wilt disease;the mechanism might be that the increase in soil pH changed the soil microenvironment,and the increase in free calcium concentration inhibited the growth of pathogens and spore germination,leading to its apoptosis.The results of the study have a reference value for revealing the mechanism of prevention and control of the fusarium wilt of watermelon by calcium oxide.