Effects Of Cover Crops In Orchard On Weeds And Soil Microorganisms

Orchard grass is one of the hot topics in recently years,which could improve soil fertility,regulating soil microbial diversity,affecting fruit quality and inhibiting the growth of weeds and it become the new management model in orchard,but this model has not been widespread in china.At present,the research focused on the selection of local grass species and the impact on orchard soil fertility and fruit quality,but there is no clear study on the effects of weeds and soil microbes after cutting and covering.In this experiment,we use the common plant decomposing to determine its allelopathy effect on weeds and compact of two common weeding control methods between plant cover and other weed control methods.The purpose is to clarify whether the grass rot has any allelopathy on the common weed seeds and seedlings in Hainan.Compare the effects of several treatment methods on weed diversity and soil microorganisms,so as to explore which weeding method is more beneficial to the soil and inhibiting the growth of weeds.In this experiment,we chose five green manure(Axonopus compressus,Lolium perenne,Stylosanthes,Stylosanthes,Medicago sativa,Desmodium heterocarpum)and black plastic film to cover the soil,Glyphosate to control the weeds.Explore the effects of several treatments on weeds and soil microorganisms.The research results are as follows:1.Axonopus compressus,Lolium perenne,Stylosanthes,Clitoria ternatea,Medicago sativa,Desmodium heterocarpum decomposing fluids have a significant inhibitory effect on the germination of four kinds of weed seeds at high and low concentrations.At high concentration,the inhibition rates of Medicago sativa,Axonopus compressus,Lolium perenne,Desmodium heterocarpum on germination of Digitaria sanguinalis seeds were 100.00%,89.67%,86.78% and 79.35%,respectively.Stylosanthes,Medicago sativa,Desmodium heterocarpum With low concentration of decomposing liquid can promote the germination of Digitaria sanguinalis,but it can inhibit the germination of other weeds.Several green manure decomposing solutions have certain inhibitory effects on root length and stem length of weed seedlings,but have little effect on dry weight and fresh weight.The comprehensive allelopathic effect index showed that different concentrations of Axonopus compressus,Clitoria ternatea,Medicago sativa,have inhibitory allelopathy on several weeds.2.Several treatment methods just like grass mulching,Herbicide and Black film mulching can effectively reduce the types of weeds,suppress the total density of weeds,change the abundance of weeds,and change the diversity of weed communities.The most common weeds in the survey are the Bacteroidetes,Compositae and Cyperaceae.theweeds species is the least in black film cover.The order of decreasing the total number of weeds relative to the control is:black film cover > Clitoria ternatea > Medicago sativa >Axonopus compressus > Lolium perenne > Desmodium heterocarpum > Herbicide > Stylosanthes.With the increase of mulching time,the total density of weeds decreased,which were control(165.50%)> Desmodium heterocarpum(91.09%)> Herbicide(61.40%)> Clitoria ternatea(60.40%)> Medicago sativa(59.80%)> Axonopus compressus(55.00%)> Lolium perenne(40.40%)> Stylosanthes(34.00%)> Black film(1.00%).Through research and investigation,we found that the community structure covered by Lolium perenne,Stylosanthes,Herbicide,black film,Lolium perenne,and Clitoria ternatea was the most stable and the least likely to be affected by the environment.3.We selected Axonopus compressus,Clitoria ternatea,herbicide treatment,and black film mulching for high-throughput microbial determination.Different mulching methods have different effects on soil fungi and bacteria.Plant cover increases soil fungal diversity and reduces soil bacterial diversity;herbicides and black film cover reduce soil fungal and bacterial diversity.The fungal fugues Chao1 index is: Axonopus compressus> Black film > control > Clitoria ternatea > Herbicide.Bacterial Chao1 index size is: control > Clitoria ternatea > Herbicide > Black film > control > Axonopus compressus Different coverage has no effect on the top 10 species in the soil microbial community species abundance(> 0.1%),but the relative abundance has a greater impact.Fungus Bate Diversity Analysis: The species with the largest difference in the abundance of Axonopus compressus species is Russulaceae,Clitoria ternatea mulching different species is Microascaceae,Black film covering is Trichosphaeriaceae,Chaetomellaceae,Trichocomaceae.Herbicide treatment is Agaricostilbaceae,Agaricaceae,Ophiocordycipitaceae.The different species of control is Pleosporaceae,Chaetimiaceae,Cystofilobasidiaceae.Bacterial Bate Diversity Analysis: The species with the largest difference in species abundance between Clitoria ternatea and other treatments at the phylum level are Deferribacteres;The largest difference in species abundance of Axonopus compressus is Deinococcus Thermus,Bacteroidetes,Tenericutes;The black film cover is Nitrospirae,Protebacteria;The herbicide treatment is patescibacteria,Armatimonadetes,Acidobacteria,Actinobacteria,Chloroflexi,Rokubacteria and Euryarchaeota.The largest difference of control in species is Latescibacteria,Dadabacteria and Nitrospinae.