Research On The Effect And Mechanism Of Relieve Banana Continuous Cropping Obstacles By Crop Rotation

The continuous cropping obstacles extensively existed in banana production in Hainan province,and rotation was one of the most effective measures to overcome it.In this study,a four-year continuous banana plantation was selected as the research object.In this plantation,pepper(Capsicum spp.),sugarcane(Saccharum spp.),wax gourd(Benincasa hispida)and pumpkin(Cucurbita spp.)were selected for rotation with banana(Musa spp.).The principal component analysis method was used to study the effectiveness of different crop rotations on soil improvement and the mechanism of rotation was analyzed by combing with root exudates,residuals and soil microflora.The results were as follows:(1)Field experiments results showed that crop rotation treatment reduced the amount of Fusarium oxysporum in the soil and improved soil quality.Among them,the soil with banana-pepper rotation and banana-sugar rotation can produce the least amount of Fusarium oxysporum,followed by the banana-wax gourd rotation and the banana-pumpkin rotation,respectively.Compared with that in the control group,the amount of Fusarium oxysporum in the soil decreased by 49.38%,23.18%,1.61%,and-47.59%after the crop rotation,respectively while incidence rate of newly-planted bananas decreased by 41.49%,34.00%,22.08%,and-47.82%after the rotation.In the principal component analysis of soil,the soil composite index had a significant positive correlation with the incidence rate and had a significant negative correlation with the yield.After crop rotation,banana-pepper treatment and banana-sugar treatment have a lowest level in soil composite index and the soil quality are the best,followed by banana-wax gourd treatment and banana-pumpkin treatment.The same results also found in the newly-planted bananas.(2)Indoor validation experiments showed that root exudate and residues of pepper and sugarcane have best inhibition effect on Fusarium oxysporum,followed by that of wax gourd and pumpkin.The inhibitory rates on FOC4 after pepper,sugarcane,wax gourd and pumpkin treatment were 13.56%,12.04%,8.77%and 10.65%,respectively;Compared with continuous cropping bananas,the number of soil-cultured Fusarium oxysporum decreased by 43.14%,38.65%,17.69%,and 5.41%,respectively,when 2%of residue was added.After 96 hours of inoculation with pepper and wax gourd residues,the inhibition rate on FOC4 was raised,followed by pumpkin and sugarcane,which were 20.65%,17.8,13.43%and 12.04%,respectively.(3)The results of high-throughput sequencing showed that compared with continuous cropping bananas,the rotation improved the relative abundance of Acidobacteria,Actinobacteria,Microsporidia,Gp4,Gp6,Gaiella,Sphaerobacter,Anaerotr uncus,Calderihabitans,Desulfocarbo,Formivibrio and Lasiodiplodia,and decreased the relative abundance of Chloroflexi,Cyanobacteria/Chloroplast,Parcubacteria,Proteobacteria,Gp2,Kedonobacter,Phenylobacterium,Ramlibacter,Sideroxydans,Opitutus,Entyloma,Penicillium,Pulchromyces and Talaromyces.Among them,the former has a significant negative correlation with the relative abundance of Fusarium oxysporum while the latter has a significant positive correlation with that.In high-abundance phyla and genera with a significant negative correlation with Fusarium oxysporum,the highest relative abundance of Acidobacteria,Actinobacteria,Gp4,Gp6,Gaiella,Sphaerobacter,Anaerotr uncus,Desulfocarbo and Lasiodiplodia was the banana-sugarcane rotation;the highest relative abundance of Formivibrio was the banana-wax gourd rotation;while the highest relative abundance of Calderihabitans was the banana-pumpkin rotation.Among the high-abundance phyla and genera that showed a significant positive correlation with Fusarium oxysporum,the lowest relative abundance of Cyanobacteria/Chloroplast and Ramlibacter was the banana-pepper rotation;the lowest abundance of Parcubacteria,Proteobacteria,Ktedonobacter,Phenylobacterium,Sideroxydans,Opitutus and Penicillium was banana-sugarcane rotation;the lowest relative abundance of Chloroflexi,Gp2 and Pulchromyces was banana-wax gourd rotation;the lowest relative abundances of Talaromyces were banana-wax gourd rotation and banana-pumpkin rotation;the lowest relative abundances of Entyloma were banana-pepper rotation and banana-wax gourd rotation.At the same time,the lowest abundance of Fusarium oxysporum was banana-sugar cane rotation,followed by banana-pumpkin rotation,banana-pepper rotation and banana-wax gourd rotation,which were 78.06%?51.60%?29.45%and 29.22%lower than those in the control group.(4)The results of field trials showed that crop rotation can reduce the incidence of banana wilt disease and increase its yield.After planting the new generation of bananas,banana-pepper rotation and banana-sugar rotation had the lowest incidence,followed by banana-wax gourd rotation and banana-pumpkin rotation,the incidence rates of which were 68.72%,44.48%,33.38%,and 27.86%lower than those in control group.Banana-pepper rotation and banana-wax gourd rotation produced the highest yield,followed by banana-sugar cane rotation,and pumpkin rotation,which compared with the control group,increased by 32.00%,25.82%,24.77%,and 10.94%,respectively.The second generation of bananas-sugarcane rotation and banana-pepper rotation had the lowest incidence and highest yield,followed by wax gourd and pumpkin.In summary,banana-pepper,banana-sugarcane,and banana-wax gourd rotation treatments can reduce the number of culturable Fusarium oxysporum,improve soil microbial flora and soil quality,reduce the incidence of the disease,and increase the yield of bananas,and provide theoretical and technical support for the study of banana continuous cropping barriers.