Effects Of Winter Wheat Varieties Intercropping On Population Growth Characterisitic And Yield

Variety mixture in crop production not noly has advantage of disease resistance,keeping stable production and increasing yield,but it also can make full use of resources(light,water and nutrients)in environment,so variety mixture is a kind of potential cultivation technology that can increase the output of crop group.But so far,this technology has not been wildly applied to wheat production.In order to solve the theories and technical problem of winter wheat mixtures,three experiments were set up at Doukou experimental station of Northwest A&F University to research wheat mixture technology systematically and deeply during two winter wheat growth season in 2014-2016,with current major varieties whose growth period was close as materials.Firstly,relationship between variety diversity and biomass,grain yield,water use efficiency of group were analyzed,and explored the theoretical basis and application prospect of variety diversity in wheat production.Secondly,the competition ability of different height varieties and the relationship between competition and yield were analyzed from the point of view of the interaction between two varieties.Finally,according to the difference of combining varieties and characteristic of increase combinations,analyzed yield-increasing mechanism and chose over yield group which was suit for popularization in agricultural production.The main results are as follows:1.The diversity theory could also promote the increase of yield and biomass in winter wheat production.Grain yield increased firstly and then decreased with the increase of variety diversity.The yield increased by 3.85%(2L),2.59%(4L),3.02%(8L)and 3.60%(16L)respectively in 2014,the increase reached significant level(P<0.05)in 2015,was 18.99%(2L),19.80%(4L),24.54%(8L)and 19.79%(16L)respectively.Above-ground biomass increased gradually with the increase of variety diversity.It increased by 0.08%(2L),0.08%(4L),1.40%(8L)and 4.11%(16L)respectively in 2014,the increase reached significant level(P<0.05)in 2015,was 16.02%(2L),22.52%(4L),22.67%(8L)and 23.08%(16L)respectively.2.Increasing variety diversity could improve root biomass and root-shoot ratio of winter wheat population,and it could add up the group shallow layer soil moisture content and root distribution in deep soil layers,and rise the group water use efficiency(WUE)significantly(P<0.05).Water use efficiency improved with the increase of variety diversity.In 2014 and 2015,the WUE of grain increased by 4.32%-6.84% and 19.42%-26.25% severally,and the WUE of above-ground biomass increased by 4.32%-6.84% and 19.42%-26.25% respectively.3.The competition ability of high variety was stronger than low variety within combined group which was composed by different height winter wheat.The relative biomass of high variety was more than 1,however,the relative biomass of low variety was less than 1.The height difference of two varieties was bigger,the competition ability of high variety was stronger,and the competition ability of low variety was worse.In combined group,spike kernel number,thousand-kernel weight,grain yield and biomass of high variety increased with its competition ability enhanced.In addition,two winter wheat varieties intercropping which plant height was complementary,their spike number all showed an increasing trend whatever plant height was high or low.4.Different height varieties intercropping could increase high variety’s root biomass and promote relative root biomass over more 1,and decrease root-shoot ratio,and improve root distribution in shallow soil layer.These all leaded to high plant grow up more vigorously.In addition,competition didn’t change low variety’s root biomass,and relative root biomass was close to 1,and improve root-shoot ratio and root distribution in deep soil layer.These made up for competition weakness in shallow soil layers,and ensured that low variety could grow normally in combination group.5.Over yield group’s characters included two types.First,the intercropping combination was composed by different height varieties,and the high one must be loose.Second,the combination could be composed by two no height difference varieties,but it must be collocated by loose one and compact one.The two field experiments all showed that population grain yield of PM9-AK58 was the largest and the most stable,its yield increased by 7.08% to 27.92% respectively in 2014 and 2015.So PM9-AK58 was the most suitable combination in production.PM9-AK58 was composed by high and low varieties,whose height difference was around 15 cm,and two varieties were loose and large leaf type.6.Mechanism of increasing yield of combined population.Over yield group’s root and shoot all had complementary effect,and it had more root biomass,larger shoot ratio and higher water use efficiency.In addition,over yield combination’s canopy could intercept more light radiation,and had larger leaf area,SPAD value and higher net photosynthetic rate of flag leaf.These all were conducive to the full grouting and promote to accumulate more dry matter,thus increased the population spike harvest index and yield.The above research results showed that increasing varieties diversity could increase winter wheat yield and improve the water use efficiency.When different height winter wheats intercropping,the tall variety could effectively use above-ground space superiority and surface soil moisture,and give full play to promote its competitive advantage.The dwarf variety could effectively use deep soil water and nutrients that can make up in the shallow soil in the competitive disadvantage.The intercropping population could realize more yield when it was composed by high pole loose variety and dwarf variety,or no height difference varieties which included loose one and compact one.So we can conclude that the multi varieties intercropping is a feasible technique for increasing yield and saving water in the dry winter wheat production area.