| Broccoli(Brassica oleracea L.var.Italic Planch)is one of the typical export vegetables with high income in the development of cold vegetable industry in Ningxia,because of the continuous expansion of planting area and the planting mode of two crops a year,the continuous cropping obstacles in actual production are highlighted year by year,resulting in the instability of broccoli product quality.It restricts the healthy and sustainable development of broccoli industry.In this study,different rotation patterns were constructed to alleviate continuous cropping obstacles and optimize broccoli planting system,which provided technical support for the sustainable production of open-field vegetables in cold areas of Ningxia.The experiment was carried out in the cold area of Ningxia(yuanzhou District,Guyuan City)in 2018-2019,and four crops(rotation)were allocated,including broccoli→potato(BMP),broccoli→scallion(BMG),broccoli→baby cabbage(BMC)and broccoli→onion(BMO).Model,broccoli as the control(BCB),through the study of different rotation patterns of crop rhizosphere soil physical and chemical properties,enzyme activity and microbial community distribution of the relationship,and ultimately determine the appropriate rotation mode.The main results are as follows:1 Rotation is more beneficial to soil nitrogen accumulation.The total nitrogen and ammonium nitrogen increased by 27.78%～31.58%and 9.09%～128.57%,respectively,and the total salt content decreased by 7.14%～50.00%.2.The soil enzyme activity was the lowest under continuous cropping,and rotation could improve the soil enzyme activity.The activity of catalase,urease,sucrase and alkaline phosphatase increased-1.92%-17.00%,48.72%-88.16%,56.00%-146.15%and 30.81%-17.00%,respectively under BMC treatment 89.83%。3.Compared with continuous cropping,soil bacterial richness index(Chao1 index,ACE index)and diversity index(Simpson index,Shannon index)were increased in rotation cropping,and Simpson index and Shannon index decreased by 0.10%～0.30%and 0.77%～1.20%respectively in BMP treatment.BMG,BMO and BMC increased by 0.30%,0.20%,0.10%～0.20%respectively.4.Proteobacteria,Actinobacteria,Campylobacter,and Acidobacterium were the dominant bacteria in all the 34 phyla of soil samples,and their relative abundances were 78.29%～82.79%.Ascomycetes were the dominant fungi in all the 8 phyla of soil samples,and their relative abundances were 73.9%～88.30%.5.The first and second principal components could explain the difference of the spatial distribution of bacteria and fungi under different treatments at the accumulative variable of 62.00%～88.70%;The results of redundancy analysis showed that the accumulative contribution rates of soil bacteria and fungi were 66.33%～78.53%,which could explain the relationship between soil bacterial and fungal community structure and soil physical and chemical properties and enzyme activity.6.The income of BMG treatment was the best,which was 2789.94～2861.29 yuan/666.7 m2,and the income of BMP treatment was the lowest,which was 1228.45～1560.64 yuan/666.7 m2.The main characters of soil nutrient,enzyme activity,microbial diversity and economic benefit under different rotation patterns of broccoli were compared and analyzed.The results showed that the comprehensive performance of broccoli→scallion and broccoli rotation with onion was better than other treatments,and the comprehensive score was in the top.Therefore,the two patterns were recommended as broccoli rotation patterns in the cold region of Ningxia. |
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