Effect Of Mixed-seeding For Forage Quality And Weeds Diversity In Winter Fallow Fields

Perennial ryegrass, white clover and milk vetch are cold-season forage common and easy to be cultivated and promoted in large area in Hunan Province. This experimental research on the mixed-seeding effect of annual ryegrass-annual legume forage mixture has been conducted at Rice Research Institute of Hunan Agricultural University in Changsha City of Hunan Province from October of2012to October of2013, with the aim of studying the mixed-seeding technology of annual forage suitable for double cropping rice winter fallow fields. Field experiment and indoor experiment have been combined to obtain the biomass and quality of mixed-seeding grass, as well as its influence on the diversity of weeds. Study on the most suitable mixed-seeding ratio of perennial ryegrass, white clover and milk vetch has also been conducted to provide a scientific basis for the intensive study and application of mixed-seeding pattern of winter fallow field forage in Hunan Province.The main results are as follows:1. The plant height of mixed-seeding grass decreases with increasing of the mixed-seeding proportion of perennial ryegrass, while increases with increasing of the mixed-seeding proportion of leguminous forage. Under the mixed-seeding of perennial ryegrass and white clover, plant height range of perennial ryegrass are0.54m-0.72m on April8,0.69m-0.86m on May8, and0.90m-1.10m on June8. Perennial ryegrass in single-seeding pattern is higher than that in mixed-seeding pattern before April8. The main reason for the above results is the inhibition on perennial ryegrass during the competition between white clover and perennial ryegrass in the early period of mixed-seeding. Under the mixed-seeding of perennial ryegrass and milk vetch, perennial ryegrass is even higher in mixed-seeding pattern with the proportion of30%perennial ryegrass and70%milk vetch than perennial ryegrass in single-seeding pattern. The plant height range of perennial ryegrass are0.58m-0.72m on April8,0.77m-0.86m on May8,0.97m-1.12m on June8.2. More suitable mixed-seeding proportion can promote the increase of grass yield and nutrient. Under different grass varieties and different mixed-seeding proportion, grass yield and quality are different. Under the mixed-seeding of perennial ryegrass and white clover, the effect of30%perennial ryegrass and70%white clover is better, with the corresponding grass yield range of24130.56kg/hm2-25914.70kg/hm2, crude protein (CP) range of14.24%-18.33%, ether extract(EE) range of8.23%-9.34%, and crude fiber(CF) range of 15.65%-17.32%. Under the mixed-seeding of perennial ryegrass and milk vetch, the effect of30%perennial ryegrass and70%milk vetch is better, with the corresponding grass yield range of24813.60kg/hm2-27213.60kg/hm2, crude protein (CP) range of14.24%-20.23%, ether extract(EE) range of7.35%-9.41%, and crude fiber(CF) range of14.90%-17.59%.3. Mixed-seeding grass can cause the change of the weed community composition. The inhibition effect on winter fallow field grass is the best under the mixed-seeding of30%perennial ryegrass and70%milk vetch, including Alopecurus aequalis Sobol, Leptochloa chinensis(L.)Nees, Ranunculus sceleratus L, and Beckmannia syzigachne (Steud.) Fern. Under such Mixed-seeding proportion, these four kind of grass dominance is minimal.4. Compared with mixed-seeding of perennial ryegrass with other grass or single-seeding of perennial ryegrass, mixed-seeding of perennial ryegrass and leguminous forage, the best mixed-seeding effect is30%perennial ryegrass and70%milk vetch. Under such mixed-seeding proportion, the increase of grass yield and quality is the best, and especially the Inhibition effect on weeds in winter fallow fields is the best.