| Orchard grasses cultivation is one of hot issues in recents years,because of its multifunctional effect,such as controlling weeds,improving soil fertility,regulating soil microbial diversity and improving fruit quality,orchard grasses cultivation has become a new safe,effective and sustainable soil management mode in orchard.At present,the domestic research on orchard grasses cultivation mainly focused on the effects on soil fertility and fruit quality.However,there are few studies on the control of weeds in orchards and the effects of green manure on soil physical and chemical properties and bacterial diversity,especially in organic orchards.The planting area and yield of kiwifruit in Shaanxi ranks first in China.At present,most of the kiwifruit orchards in Shaanxi Province are dominated by cleaning tillage,resulted in a series of soil quality problems such as soil structure destruction and biodiversity reduction.The study was divided into two stages of autumn sown in 2020 and spring sown in 2021,the natural orchard grasses cultivation was used as the control(CK),Lolium perenne L.+Vicia villosa R.(Mode 1),L.perenne+Melilotus officinalis L.(Mode 2),L.perenne+Trifolium repens L.(Mode 3)and Vulpia myuros(Mode 4)in autumn sown,Lolium multiflorum+V.villosa R.(Mode 5),L.multiflorum+Astragalus sinicus L.(Mode 6)and L.multiflorum+Glycine max L.(Mode 7)in spring sown,by studying the plant growth of different orchard grasses cultivation species and combinations,the effects of orchard grasses cultivation and green manure on soil physical and chemical properties and bacterial communities in 0 ~ 20 cm,preliminary exploration on a set of orchard grasses cultivation and green manure mode of organic kiwifruit orchard in Guanzhong area,so as to provide theoretical basis and technical support for the development of kiwifruit industry in China.The main research results are as :(1)Orchard grasses cultivation can effectively control orchard weeds.The overwintering rate of orchard grasses cultivation species and the aboveground biomass of artificial orchard grasses cultivation treatment were compared.The results showed that V.myuros had strong adaptability and cold tolerance,and its overwintering rate was higher than that of other orchard grasses cultivation species(P<0.05),reached 93.45 %,and the strongest ability to control weeds.Mode 1 has the highest aboveground fresh yield in artificial orchard grasses cultivation group in autumn sown,reached 1107.41 g·m-2;Mode 7 has the highest aboveground fresh yield in spring sown artificial orchard grasses cultivation group,reached3316.67 g·m-2,followed by Mode 5.(2)In the 0~20 cm soil layer,the soil water content of autumn sowning artificial orchard grasses cultivation treatment group was higher than CK,but there was no significant difference(P> 0.05).In 0~5 cm,5~10 cm,10~15 cm and 15~20 cm soil layers,the soil water content of Mode 1 by 22.44%,7.57 %,6.60% and 12.87%,respectively,compared with natural orchard grasses cultivation.The average soil water content in 0~20 cm soil layer of Mode 2 was lower than that of other artificial orchard grasses cultivation treatments.The changes of soil water content varied among different orchard grasses cultivation treatments in spring sown,the soil water content of the three artificial orchard grasses cultivation treatments in the 15~20 cm soil layer was higher than that of natural orchard grasses cultivation,but there was no significant difference(P>0.05).(3)In the autumn sowing artificial orchard grasses cultivation treatment group,Mode 4reduced the soil p H in the orchard,and the spring sowning artificial orchard grasses cultivation treatments increased the soil p H.After returning green manure to field,the p H of autumn sowing artificial orchard grasses cultivation treatment was higher than natural orchard grasses cultivation,and the p H of Mode 7 was lower in spring sown.In autumn sown and spring sown,the content of soil organic matter increased in all treatments.The organic matter content of Mode 1 increased by 38.63 % compared with natural orchard grasses cultivation in autumn sown.After returning to the field,the effect of Mode 4 was the most obvious,followed by Mode 1.Compared with the natural orchard grasses cultivation,the organic matter of Mode 6 was significant in spring sown(P<0.05),followed by Mode 5.After returning to the field,the effect of Mode 5 was the most obvious,followed by Mode 7.(4)The activities of soil urease,sucrase,alkaline phosphatase and catalase activities in autumn sowing artificial orchard grasses cultivation treatment group were higher than natural orchard grasses cultivation,Mode 1 increased urease,sucrase and alkaline phosphatase activities most significantly(P<0.05),increased by 39.83 %,60.79% and20.56%,respectively.After returning green manure,Mode 3 increased soil urease,alkaline phosphatase and catalase activities most significantly(P<0.05),increased by 9.94%,20.31%and 3.86%,respectively.The activities of soil urease,alkaline phosphatase and catalase in spring sowing artificial orchard grasses cultivation were higher than natural orchard grasses cultivation,and the activity of soil sucrase was decreased by Mode 6.The activities of soil urease,sucrase,alkaline phosphatase and catalase in the artificial orchard grasses cultivation treatment group were higher than natural orchard grasses cultivation after green manure,and Mode 5 was significant(P<0.05).(5)The soil bacterial species richness of Mode 3 in autumn sowing artificial orchard grasses cultivation treatment group was the highest,after green manure,the richness and diversityof Mode 2was the highest,but there was no significant difference compared with natural orchard grasses cultivation.The distribution of soil bacterial communities in autumn sown was relatively concentrated,and there was no obvious separation among orchard grasses cultivation and green manure treatments.Proteobacteria,Acidobacteria and Planctomycetes were the dominant groups in orchard grasses cultivation treatments;after returning green manure,Proteobacteria,Acidobacteria and Actinobacteria were the dominant groups.The effect of Mode 6 on bacterial community in spring sowing artificial orchard grasses cultivation treatment group was the largest,followed by Mode 5.After returning to field,the species richness and diversity of Mode 5 was the highest,Chao1 index was 2946.49,Shannon index was 10.63,but there was no significant difference compared with natural orchard grasses cultivation.The soil bacterial community structure of the artificial orchard grasses cultivation treatment group was similar,and there was no significant difference among treatments.However,the bacterial community structure of the artificial orchard grasses cultivation treatment group was significantly different from that of the natural orchard grasses cultivation.After returning to the field,the soil bacterial community structure of each treatment was significantly different.Proteobacteria,Acidobacteria and Actinobacteria were the dominant groups in orchard grasses cultivation treatments;after returning green manure,Proteobacteria,Acidobacteria and Planctomycetes were the dominant groups.The soil p H decreased after mulching with V.myuros in autumn sown,which was beneficial to the survival of Acidobacteria.Orchard grasses cultivation and returning to field of L.multiflorum+V.villosa can significantly increase the abundance of Gemmatimonadetes in spring sown.In the cultivation of green manure and returning production measures in kiwifruit orchards in Guanzhong Plain,it is recommended to adopt the planting mode of L.perenne+V.villosa R.to increase soil organic matter and soil enzyme activity.The burying and returning of ryegrass can increase the richness and diversity of soil bacterial species. |
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