Research On Soil Weed Seed Bank Of Corn Field In Northern Shaanxi

Food is the top priority for the people,and food is based on agriculture.Agriculture is the foundation of national economic and social development.The advancement of science and technology has greatly promoted the development of modern agriculture.However,weeds in farmland have always been an important factor that troubles agricultural production.For a long time,manual weeding has been the longest and most labor-intensive production process in agricultural production in northern Shaanxi.Based on this,this study takes weed seed bank of three main types of corn planting in northern Shaanxi as the research object by using the indoor seed germination method.It is studied in the four seasons of spring,summer,autumn and winter respectively.This research mainly focuses on some basic characteristics,such as species composition,storage,life form,vertical distribution and species diversity.In addition,it explores the occurrence of weed seed bank in different sites,seasons and vertical layers.The similarities and differences of various site weed seed banks were compared.Key findings are as follows:(1)Weeds germinating in the soil weed seed bank in northern Shaanxi are 14 families and 32 species in total,including 9 species in the Compositae family,7 species in the Gramineae family,3 species in the Chenopodiaceae and Leguminosae families,and other families and species in a single family.From the perspective of germination quantity,it is mainly composed of the Compositae,Chenopodiaceae,Portulacaceae,and Gramineae.From a lifestyle perspective,there are 18 annual(Th)weeds and 14 perennial(Ph)weeds.Among them,the single species with the highest germination rate of Th weeds is Chenopodium glaucum,and the single species with the highest germination rate of Ph weeds is Sonchus arvensis.The Th weed species accounts for 56.25%of the total number of species,and the density accounts for 71.33%of the total germination.It can be seen that the soil weed seed bank in the northern Shaanxi corn field is mainly composed of Th weeds.(2)The density range of the 0-20 cm soil layer for three types of sites in four seasons is from(1960±103)to(8720±469)grains/m~2,with the highest density being on the flat land in spring and the lowest density being on the terrace in summer.There is a significant difference in the density of weed seed banks among different sites,with the overall performance as follows:flat>slope>terrace.The density of weed seed banks varies significantly in different seasons,with a size relationship of spring>winter>autumn>summer.The main dominant weeds,in order of germination quantity,are Chenopodium glaucum、Sonchus arvensis、Portulaca oleracea、Setaria viridis、Artemisia annua、and Artemisia capillaris.These dominant weeds are the key objects that need to be controlled.Weeds have the largest number in spring and winter,and it is recommended to focus on weed prevention before spring sowing.(3)The number and density of weed seed banks show a decreasing trend as the vertical depth increases.From the distribution of dominant weeds,there is a large distribution of Chenopodium glaucum、Sonchus arvensis、and Portulaca oleracea in the 0-20 cm(four layer)soil layer.Setaria viridis is mainly distributed in the 5-15 cm soil layer,Artemisia annua and Artemisia capillaris are mainly distributed in the 0-5 cm layer.From different sites,the size relationship of the total density of each vertical layer in four seasons is as follows:flat land>slope land>platform land.From the overall perspective of the four seasons and three types of sites,the density relationship of the four vertical soil layers is:0-5 cm>5-10 cm>10-15 cm>15-20 cm,with over 70%of weed seeds distributed in the 0-10 cm layer.It is recommended to focus on controlling weeds within this depth range.(4)The Shannon-Wiener(H),Margalef(M),Pielou(E)and Simpson(D)of the plateau changed with seasons,showing a trend of first decreasing,then increasing and then decreasing;The species diversity indices H,M,E and D of the slope land showed a decreasing trend with seasonal changes,and the relationship between the magnitude was:spring>summer>autumn>winter;Except for the M index,the other three species diversity indexes of the platform showed a decreasing trend with seasonal changes,similar to the trend of the slope.(5)The species similarity index between different sites in the same season is relatively high,ranging from 0.62 to 0.90,and mainly concentrated between 0.70 to 0.78;The species similarity index between different seasons and the same site ranges from 0.22 to 0.67;The species similarity index range between different seasons and different sites is:0.33-0.67.Among them,the species similarity index between slope and platform in autumn is the highest,at 0.90;The similarity index between autumn and winter in the plateau is the lowest,at 0.22.In summary,this study clarified the basic characteristics of soil weed seed banks in cornfield soil in northern Shaanxi.Additionally,it explored the occurrence patterns of soil weed seed banks in different sites,seasons,and vertical layers.The results of this study can provide a theoretical basis for the precise management and comprehensive control of weeds in different seasons and locations in northern Shaanxi,and provide a basis for further research on other aspects,such as site selection,weed control time selection,and the use of controlled tillage depth to control weeds.