Effects Of Biochar And Intercropping With Potato Onion On Growth And Development Of Continuously Monocropped Tomato And Soil Microbial Communities

Continuous monocropping of vegetables has negatively affected soil quality.The soil amendment with biochar with distinguish characteristics such as high pH,large surface area and cation exchange capacity that enables it to improve soil quality has gained significant attention is recent time.At present,there is mounting literature describing benefits of biochar for improving.Soil health,however,most of the studies explored effects of biochar on monocropping systems.Here,we investigated effects of biochar amendment on intercropped tomato with potato onion in 2 years long greenhouse experiment.The treatments include monocropped tomato,tomato intercropped with potato onion with no and 0.3%,0.6%and 1.2%of biochar amendments.The soil physicochemical properties,enzyme activity,tomato growth and development and nutrient uptake were evaluated,and the abundance of total bacteria,total fungi,pseudomonas spp.and bacillus spp.in tomato soil was estimated using quantitative PCR,while changes in microbial community composition was studied by Illumina Miseq.The purpose of this study was to evaluate the improvement effect of biochar on continuous soil associated culture and the interaction effect between biochar and intercropping and provides theoretical basis and technical support for biochar application in alleviating continuous cropping barrier in different cultivation modes.The main findings of this study are as follows:1?Compared with mono-cropping,Intercropping increased the plant height,dry weight of tomato,soluble sugar and sugar-acid ratio and lowered the organic acids of tomato fruit quality with no and 1.2%biochar,and increased the tomato yield in treatments of 0.6%and 1.2%biochar of 2018.Compared with no biochar,1.2%biochar treatment increased the plant height,dry weight,yield,Vc,soluble sugar and sugar-acid ratio and lowered the organic acids by 8.67%,53.06%,59.74,25.27%,21.48%,50.65%,20.35%in mono-cropping and 4.39%,20.48%,67.78,19.65%,15.66%,37.25%,17.07%in intercropping,respectively.2?As compared to monocropped tomato,intercropping increased the uptake of N,P,K,Ca and Si with no biochar.1.2%Biochar also increased the uptake of N,P,K,Ca and Si by 8.91%,8.43%,5.83%,8.51%and 9.57%in intercropped than monocropped tomato.Compared with no biochar,1.2%biochar treatment increased the uptake of N,P,K,Ca and Si by 71.11%,66.00%,62.20%,84.31%,57.14%in monocropping and 23.32%,24.14%,26.52%,21.16%,29.01%in intercropping,respectively.3?Compared with monocropping,intercropping increased the pH and lowered NO3"-N with no biochar,and lowered the bulk density with 1.2%biochar.Compared with no biochar,1.2%biochar treatment increased the soil pH and lowered the bulk density by 2.05%and 3.96%in monocropping and 2.01%and 6.00%in intercropping,respectively.4?Compared with mono-cropping,1.2%biochar treatment increased the invertase activity with biochar and dehydrogenase activity in intercropping.Compared with no biochar,1.2%biochar treatment increased the Catalase activity in inter-and monocropping,Dehydrogenase activity in intercropping and Invertase activity in monocropping.5?Q-PCR results showed that,compared with monocropping,intercropping increased the abundance of fungi with no biochar and the abundance of bacteria,fungi and bacillus spp.with biochar of 1.2%.Compared with no biochar,1.2%biochar treatment increased he abundance of bacteria,fungi,pseudomonas spp.and bacillus spp.in intercropping as well as in monocropping.6?Miseq results showed that biochar had no significant effect on bacterial diversity,but lowered the fungal diversity in 1.2%biochar treatment.Compared with monocropping,intercropping increased the relative abundance of potentially beneficial bacteria of Solirubrobacter,and lowered the potential pathogenic bacteria of Kribbella when 0.6%and 1.2%of biochar was used,while increased the potentially beneficial fungi of Pseudeurotium with no and 1.2%biochar,and lowered the potential pathogenic fungi of Iyonectria when no biochar was introduced.7.NMDS and RDA analysis showed that amendment of biochar at all concentrations affected the community structure of bacterial and fungal communities.Moreover the changes in soil bacterial community were strongly correlated with soil characteristics such as pH,NO3--N and EC,while the composition of fungal community was closely related to soil NO3--N and water content.In conclusion,compared with monocropping,the non and 1.2%biochar had more significant advantages in improving soil physical and chemical properties(pH,NO3--N and bulk density),increasing soil enzyme activity,and promoting tomato plant growth and yield.