The Study Of Interspecific Relationship And The Characteristics Of Weed Community Of The Mixed Cropping Annual Artificial Grassland In The Up Stream Of Shiyang River

The study of interspecific relationship and the characteristics of weed community of the mixed cropping annual artificial grassland in the up stream of Shiyang River showed that:1. There were not only existed the competition which was negative interaction, but also subsisted the synergia which was positive interaction of the different species in the mixed cropping artificial grassland. Competition and synergia were the two sides of interspecific relationship. The different species in the same grassland had the competition, restriction and synergia, reciprocity in the same time. The competition made the different species survived and developed through attaining resource, and the synergia made the different species reach the sustainable development through saving recource.2. The study of interspecific synergia effect of the treatments about Oat+Vetch mixed artificial grassland in the up stream of shiyang river showed that the interspecific synergia effect on the resources, such as solar energy, nutrient, water, of oat with vetch in mixture raised utilization rate of resource, increased the height of the whole community and advanced the dry material yield per hectare. The most suitable treatment of mixture was Oat(76kg/hm~2)+ Vetch(42kg/hm~2). In this treatment, the dry material yield was 5900kg/hm~2, increased the yield 51% and 37% than the single culture of Oat and Vetch. The economic profit was pretty nice of this treatment, and the pure income was 3020 RMB per hectare. The mixed cropping was able to solve the question that the excess utilization of the winter-spring pasture and the imbalance of forage grass with the livestock. Moreover, it also had the ability to maintain the well-balanced production of stockbreeding and protected the ecological environment of the pasture.3. The investigation of the competitive ability of Oat in the community under the different sowing density of Vetch indicated that as the growing of the sowing density of Vetch, the fresh yield of individual plant of Oat descended from slow to fast, and more dense the Vetch was, more quick the fresh yield of individual plant of Oat fell. The fresh yield of individual plant of Oat in the community which the sowing density of the Vetch was 60 kg/hm~2 just accounted for 60.84% and 61.58% of single cropping of Oat and of the community containing 10 kg/hm~2 of the Vetch, As the growing of the sowing density of Vetch, the trill number of Oat presented the trend which First increases and then decreases. The trill number of individual plant of Oat was seven when the sowing density of Vetch was 10 kg/hm~2 and 20 kg/hm~2; the trill number of individual plant of Oat was four when the sowing density of Vetch was 60 kg/hm~2. The trill number of seven was the maximum, and the trill number of four was the minimum. The increasing of the sowing density of Vetch restrained the growth and advanced the reproductive growth.4. The research of the characteristics of weed community the mixed cropping of Oat with Vetch and common Vetch revealed that the intensity of weed occupied was in a very great extent changes in different communities. The harm of the weed was the most gently in the community of Oat(60%)+Vetch(10%)+Common Vetch(30%),the total coverage of weed accounted for 37% of the total coverage of forage; The harm of the weed was the most grave in the community of Oat(50%)+Vetch(25%)+Common Vetch(25%), the total aboveground phytomass of weed accounted for 31%of the total aboveground phytomass of forage; the fresh yield of forage was the community of Oat(33%)+Vetch(33%)+ Common Vetch(33%).By all trails, the ability of competition, synergia and restraining the weed had the distinguishing difference in different community even if the species were absolute same. Balancing the relationship of the competition, synergia and restraining the weed in community could improve the yield and stability.