The Competitiveness Of Cocksfoot(dactylis Glomerata L.) With Companion And Volunteer Species Under Various Mixture Ratios

Cocksfoot(Dactylis glomerata L.) is a widely grown temperate perennial grass for livestock production worldwide. Recent studies have observed that cocksfoot plants inhibit the growth and development of companion species and there are less weeds or volunteer species in cocksf oot stands. Three experiments were conducted to quantify the allelopathic effects of cocksfoot to companion grasses and legumes, and to the seed germination and development of these species. Experiment 1 used 4 monoculture treatments [1. cocksfoot; 2. brome(Bromus inermis Leyss.); 3. white clover(Trifolium repens L.); 4. lucerne(Medicago sativa L.)] and 9 mixtures between cocksfoot and brome/white clover / lucerne in 3 mixtures ratios. Experiment 2 used different concentrations(0, 25%, 50%, 75%, 100%) of cocksfoot rhizosphere extracts to test the germination characteristics and seedling growth of annual ryegrass(Lolium multiflorum L.), Siberian wildrye(Elymus sibiricus L.), Elymus nutans Griseb., lucerne, and white clover. Experiment 3 used 4 monoculture treatments [1. cocksfoot; 2. brome; 3. white clover; 4. lucerne], 15 mixtures between cocksfoot and brome/white clover/lucerne in 5 mixtures ratios and a blank control(no pasture sown). The experiments were designed using a randomised complete block with 3(Experiment 1), 4(Experiment 2) and 4(Experiment 3) replicates. The main research results are as follows:1. Experiment 1 showed cocksfoot cv. Chuandong displayed stronger growth and tiller ing capacity than all companion grasses or legumes regardless of the sown proportions of the species. As a result, herbage accumulation of cocksfoot gradually increased with increasing mixture proportion of cocksfoot. The cocksfoot percentage was increased by 26%- 65% for herbage accumulation, and by 61%- 82% for tiller/growing point per m2 than all companion grasses or legumes. In contrast, the percentage variation of cocksfoot on herbage accumulation and tiller density in the mixtures based on its designed proportions gradually decreased with increasing sown proportion of cocksfoot.2. Experiment 2 showed that there were significant interactions(P < 0.01) between cocksfoot rhizosphere extracts and the tested species. The extract reduced the germination rate, energy and vigour of all tested grass and legume species at higher concentrations. It also inhibited at the root and shoot length of tested grasses and some legumes. The root and shoot length of lucerne were relative high regardless of the extract concentration.3. Experiment 3 showed that the total herbage accumulation of pasture was higher under different mixture ratios between cocksfoot and lucerne than monoculture. The herbage accumulation of weed was lower under mixture treatments. The tillers of cocksfoot gradually increased with time regardless of the proportion of companion species. The tiller/growth points/branches of brome, white clover and lucerne gradually decreased with decreasing sown proportion of cocksfoot, there was no grass weed under cocksfoot monoculture at the end of 2015.4. In comparison to companion species, the tiller density of cocksfoot increas ed with time and the designed proporyion in mixture. In comparison to the content of CP, NDF and ADF on monoculture cocksfoot, the percentage of CP, NDF and ADF were higher on cocksfoot under various mixture ratios. The figure for brome and lucerne were higher on CP under different mixture rations than monoculture. In contrast, the percentage of ash was higher on cocksfoot under various mixture ratios than monoculture cocksfoot.5. Soil microorganism and enzyme activity gradually decreased with increasing soil depths. The quality of soil microorganism was highest under various mixtures, followed by the mixtures between cocksfoot and brome, with mixtures between cocksfoot and white clover being the lowest.The inhibition of Cocksfoot plants on tiller density and herbage accumulation of companiaon and volunteer species and the strong allelopathic effects of cocksfoot on the plant growth and seed germination of other species have great potential to develop weed management strategies for grazing and mixed farming systems using this species.