Effect Of Grafting On Soil Microbial Diversity And Biological Properites In Rhizosphere Of Watermelon

Grafting experiments were conducted on watermeleon by using the rootstocks which including pumpkin, gourd and wild watermeleom. Meanwhile, three kinds of scions were also used to compare their ability with the grafted seedling. The results are showed as follow:(1) Soil pH and the contents of total nitrogen, phosphours, potassium and organic matter in rhizospher of grafted seedling, especially with the pumpkin rootstock were significantly higher than those in rhizosphere of non-grafted seedling. In addition, the contents of available nitrogen, phosphours and potassium were also showed the same trend.(2) The numbers of culturable microorganisms in rhizosphere, which including bacteria, fungi and actinomycetes were showed different trends in grafted seedling and non-grated seedling. The numbersof culturable bacteria and fungi in rhizosphereof grafted seedling especially with the rootstock of pumpkin were significantly higher than those in non-grafted seedling. However,e the number of culturable actinomycetes in rhziospheres had no significantly different.between grafted and non-grafted seedling.(3) Soil microbial biomass carbon and nitrogen in rhizospheres of grafted seedling were all higher than those in non-grafted seedling. Meanwhile, the order in grafted seedling were showed as feiiow in turn.i.e. pumpkin rootstock>gourd rootstock> wild watermelon rootstock.(4) Beta glucosidase,which involving in the carbon cycle in soil, its activity in rhizhosphere of grafted seedling and non-grafted seedling in the order with pumpkinrootstock> gourds rootstock> wild watermelon rootstock>nom-grafted seedling. Similarly, phosphatase activity, was showed the order withpumpkin rootstock>non-grafted seedling>gourd and wild watermelon rootstocks, and there was.no significant difference between gourd and wild watermeleon rootstocks. Aminopeptidase activity, less commonly, it was irregular with the treatment of grafting or non-grafting.But in general, the soil enezyme activitities in rhizosphere of grafted seedling, especially with the pumpkin rootstock, were all higher than those in the other two rootstocks(5) Indices of bacterial diversity, evenness and richness were all the highest in rhizosphere with pumpkin rootstockamong all the treatments. Meanwhile,it was the order with gourd and wild watermeleon rootstocks. Based on the above results, higher microbial activities and diversity in rhizospheres of grafted seedlings, in paricularly in the pumpkin and gourd rootstocks, may be the important reasons for increasing their ability than those of non-grafted seedlings in resistant to soil-borne diseases or other stresses from the environment.