Effects Of Glomus Mosseae And Sterilization Treatment On Soil Fertility And Cucumber Seedling Growth In Greenhous

Firstly,to clarify the effects of two sterilization methods on soil fertility in the study,the cucumber continuous cropping soil was selected as experimental material,and it was sterilized by high temperature and reductive soil disinfestation,respectively.High temperature was designed by 50℃and 55℃.Citrus peel（C/N=28.8）was used as organic material in reductive soil disinfestation,three citrus peels addition levels（0,0.25%,0.5%）were designed.Secondly,the sterilized soil was used in pot experiment,and cucumber（variety:“Mini”fruit cucumber）were cultivated in the soil individually,and Glomus mosseae was inoculated during seedling cultivation.The effects of G.mosseae and sterilization on the growth and physiological metabolism of cucumber seedlings were investigated,which will be helpful to find a scientific and effective method to alleviate continuous cropping obstacles in cucumber production.The main results of the study are as follows:（1）The soil fertility was significantly improved by 55℃sterilization and adding0.25%citrus peels reductive soil disinfestation.Compared with the non-sterilized treatment,the contents of alkaline hydrolysable nitrogen,available phosphorus,organic matter and urease activity of the two treatments were increased,while the SO₄^2-content decreased.The content of alkaline hydrolysable nitrogen,available phosphorus,organic matter and urease activity of soil treated by 55℃were 1.09 times,1.63 times,1.05 times and 1.66 times of that pre-sterilization,respectively.In addition,adding 0.25%citrus peels was 1.1 times,1.89 times,1.04 times and 1.61 times those of pre-sterilization,respectively.Compared with the pre-sterilization treatment,the SO₄^2-contents of 55℃sterilization and adding 0.25%citrus peels reductive soil disinfestation decreased by26.86%and 15.24%.In addition,phosphatase activity of soil disinfested by adding 0.25%citrus peels was significantly positively correlated with the available phosphorus content.（2）The number of fungi in soil was significantly reduced by 55℃sterilization and adding 0.25%citrus peels reductive soil disinfestation,meanwhile,the ratio of bacteria and fungi increased.For the two treatments,the number of bacteria in soil were 1.26 times and 1.44 times those of pre-sterilization,respectively,while the number fungi in soil decreased by 45.65%and 28.26%compared to the number of fungi in soil pre-sterilized,respectively.（3）The growth of cucumber seedlings was promoted by inoculation with G.mosseae on continuous cropping soil or soil sterilization.Interestingly,in the 55℃sterilized soil G.mosseae promoted the cucumber seedlings growth,however,in the reductive disinfested soil the growth of seedlings was inhibited by G.mosseae.In the 55℃sterilized soil,the mycorrhizal infection rate reached 32.5%,and leaf area and the seedlings’qualities index of mycorrhizal seedlings increased by 49.69%and 97.4%,respectively,compared with the corresponding non-mycorrhizal seedlings.（4）Under the condition of 55℃sterilization,G.mosseae improved the nutrients level of cucumber seedlings to some extent.On the 55℃sterilized soil,nitrogen,phosphorus and potassium uptake in shoots of mycorrhizal seedlings was 1.03 times,1.33times and 1.29 times those of the corresponding nonmycorrhizal seedlings.At the same time,the contribution rates of G.mosseae to calcium,magnesium and iron absorption in shoots of seedlings were 34.1%,32.71%and 55.76%,respectively.（5）On the 55℃sterilization soil,the contents of chlorophyll,flavonoids and total phenols in the shoots of seedlings inoculated with G.mosseae increased,and the above indexes were 2.50 times,1.03 times and 1.02 times those of seedlings non-inoculated G.mosseae.Meanwhile,compared with non-mycorrhizal seedlings,the content of soluble sugar in mycorrhizal seedlings roots decreased.The number of bacteria increased,but the number of fungi decreased in rhizosphere of seedlings inoculated with G.mosseae regardless of soil sterilization.Moreover,the ratio of bacteria and fungi in rhizosphere of cucumber seedlings inoculated with G.mosseae was 1.05 times that of continuous cropping soil inoculated with G.mosseae alone.In conclusion,for continuous cropping soil,its fertility was enhanced both by high temperature sterilization and by RSD,at the same time environment of seedlings growth was improved,which provided the basis for healthy seedlings.Among them,55℃sterilization and adding 0.25%citrus peels reductive disinfestation are effective.In 55℃sterilized soil,after the seedlings were inoculated with G.mosseae,the nutrient level,physiological metabolism and rhizosphere environment of seedlings were improved,which promoted the seedlings growth and alleviated continuous cropping obstacles.