| With the rapid development of China’s facility vegetable industry,the area of facility vegetables has been the first place in the world.However,due to the continuous cropping of facility crops or the extension of planting years,Progressive deterioration of the soil environment,such as the decrease of pH value,the reduction of organic matter content,and the accumulation of autotoxic substances secreted by roots in the soil,which seriously threatens the sustainable development of facility vegetables.In this study,biochar and nano-carbon were added to unsubstituted continuous cropping soil,biochar and nano-carbon were added to in-situ earthworm replacement continuous cropping soil,and biochar and nano-carbon were added to in-situ earthworm replacement to change soil nutrient status and improve nutrient absorption by plants.The effects of biochar and nano-carbon on soil physical and chemical properties of facilities vegetables,crop growth and yield quality were studied,and the following conclusions were drawn.1.Effects of earthworm-different carbon sources on soil physicochemical properties and tomato growth and development(1)Earthworm in situ substitution of continuous soil significantly increased soil nutrient content and enzyme activity compared to continuous soil treatment.The highest soil fast-acting nitrogen and total phosphorus content were found in earthworm in situ with biochar addition treatment,which significantly increased 542.23%and 232.52%,respectively,compared to continuous sandy soil.The highest soil fast-acting phosphorus,total nitrogen,organic matter content and soil urease and sucrase activities were found in the earthworm in situ with nanocarbon addition treatment,which significantly increased 893.21%,871.23%,674.32%,121.25%and 438.87%,respectively,compared to the continuous sandy soil.It showed that the addition of biochar and nanocarbon treatment to earthworm manure increased the soil nutrient content and enzyme activity to some extent.A total of 911 metabolites were detected by UPLC-MS/MS analysis,and a total of 11 differential metabolite classes were screened,namely alkaloids,amino acids and their derivatives,flavonoids,lignans and coumarins,lipids,nucleotides and their derivatives,organic acids,Sugar,phenolic acids,terpenoids,and quinones.Among them,earthworm in situ substitution+nanocarbon and earthworm in situ substitution+biochar treatments showed significant up-regulation of cottonseed and D-glucose,while earthworm in situ substitution+biochar and nanocarbon treatments showed significant down-regulation of benzoic acid and its derivatives compared to the control.It showed that the autotoxic substances affecting the growth and development of tomato plants were mainly benzoic acid and its derivatives in phenolic acid metabolites.(2)Earthworm in situ substitution of continuous soil significantly increased tomato plant biomass and plant nutrients compared to the continuous soil treatment,and the highest above ground part dry weight,fresh weight,above ground total phosphorus and total potassium contents were found in the earthworm in situ with the addition of biochar treatment,which significantly increased 27.45%,56.65%,55.12%and 90.93%,respectively,compared to the continuous sandy soil.(3)Earthworm in situ substitution of continuous soil significantly increased tomato fruit quality and yield compared to continuous soil treatment.Tomato fruit VC content significantly increased by 62.23%,soluble sugar content significantly increased by 34.24%,soluble solids content significantly increased by 3.89%,and yield significantly increased by 40.11%.earthworm in situ with biochar treatment had the highest VC and yield,and earthworm in situ with The highest soluble sugars and soluble solids content were found in the fruits treated with nano carbon.(4)Based on the principal component analysis of soil nutrients,soil enzyme activities,tomato growth indexes,photosynthetic characteristics,biomass,tomato quality and yield indexes,it is concluded that earthworm in situ replacement of continuous cropping soil+biochar treatment is the optimal treatment in this study.2.Effects of soil extracts on seed germination and seedling survival under earthworm-different carbon sources interaction(1)Compared with the control CK,the continuous root soil leach treatment had more significant effects on tomato seed germination and seedling growth than the earthworm in situ alternative root soil leach treatment.The germination potential,germination rate,germination index,vigor index,root length and shoot length were higher in earthworm in situ soil leach than in continuous root soil leach treatment,while earthworm in situ alternative+biochar leach treatment had the least reduction in seed germination potential,germination rate,germination index,vigor index,root length and shoot length,17.23%,15.05%,18.35%,28.32%,14.32%,and 15.93%lower,respectively.Compared to the control CK,the plant height,stem thickness,leaf area,POD and CAT contents of earthworm in situ soil leach were higher than those of continuous soil leach treatment,while earthworm in situ replacement+biochar leach treatment had the least reduction in seedling plant height,stem thickness,leaf area,SPAD,POD and CAT values,with 12.15%,19.32%,13.21%,8.32%,2.32%，and 8.65%,respectively.(2)Based on the principal component analysis of seed germination,seed growth,tomato seedling growth index,leaf enzyme activity and other indexes,it was concluded that earthworm in situ replacement of continuous cropping soil+biochar extract treatment had the lowest inhibitory effect on tomato seed germination and seedling growth.In general,the "earthworm-different carbon source" soil system had a better overall effect on tomato plants than the sand cultivation system.Among them,earthworm in situ substitution for continuous cropping soil+biochar treatment was the optimal treatment to alleviate the soil deterioration problem caused by continuous cropping of vegetables in facilities. |
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