The chromosome numbers and karyotypes of Hemarthria compressa cv.Guangyi and wild accession T003 were researched by common root tip squash method.The results showed that:(1) the base chromosome number of Hemarthria compressa was x=9;(2)'Guangyi'was hexaploid and the karyotype formula was 2n=6x=54=34m+10sm(2SAT)+6st+2t+2T,index of asymmetry was 61.43%,belonged to 2B type;(3) T003 was tetraploid and the karyotype formula was 2n=4x=36=14m+10sm(2SAT)+8st+4T,index of asymmetry was 65.67%,belonged to 2C type.

The daily changes of pollen density and the dispersal patterns of Hemarthria compressa were measured by air pollen trapping method.The results showed that there were two peaks of flowering time during 6:00-8:00 and 15:30-19:00,and the highest amounts of pollen grains collected was during 16:00-18:00.We found that wind speed affected the distances of the pollen grains distributions.The pollen grains distributed within the circle of 5 m from the pollen grain originate place,when the wind speed was lower thatn 1 km/h(0 grade) or between 1-5 km/h(1 grade),and within the circle 21 m when the wind speed was between 12-19 km/h(3 grade).The plant stands comes from the same mother plant in the areas of pollen distributed,so the cross-pollination in the same plant stand was common.The dilemma between pollen distribution pattern and cross pollination reproduction system was one of the reason of low seed set.

The quality of whipgrass silages were evaluated in different moisture content treatments （75.3%, 64.2% ,54.6%） with the previously fermented juice （PFJ） （5 ml/kg）. After 45 d ensilaged, the quality of silages were analyzed from the visual and nutrition values. The results showed that in moisture 64.2% and 54.6%, the stems and leaves of the silage were kept well, which got higher scores in the sensory value estimate, the pH and amount of ammonia-N were lower, and the quantity of lactobacillus and the amount of crude protein were higher than that of in moisture 75.3%. But the quantity of other bacteria in moisture 54.6% was significantly higher than that of in moisture 64.2%. So it was the best choice to ensilage whipgrass in moisture 64.2% with 5 ml/kg previously fermented juice.

The object of this experiment was to discuss the effect of the three annual legumes(Vicia villosa L.,Vicia sativa L.and Pisum sativum L.) on the yield and quality of whipgrass when they were overseeded into whipgrass sward in autumn by observing the growth states of these oversown annual legumes and measuring the yield and chemical components of forage.The results showed that the oversown legumes all germinated in 6-7 days and their autumn were in the middle of May.During the period of experiment,all these treatments of overseeding legumes had a higher yield of forage than that of the control and Vicia villosa L.had a good better ability to improve the yield.But with the increasing of harvest time,the crude protein concentration decreased and neutral detergent fiber(NDF) and acid detergent fiber(ADF) concentration increased,and Vicia villosa L.and Vicia sativa L.were both good at improving the quality of forage.To sum up,compared with the control,the treatment of overseeding annual legumes in autumn increased by 36.1%、54.4%、43.4% respectively and it was obviously to improve the forage quality in spring(P<0.05).

This experiment was to evaluate the producing characteristics of mixed cut-grassland with different ratio of whipgrass(Hemarthria compressa cv.Guangyi) and alfalfa(Medicago sativa cv.Shengshi) by measuring the height of plant,canopy and yield before each cut,and then supply a theoretical basis for the building and management of mixed cut-grassland.The results showed that the treatments of LC2(50% Guangyi +50% Shengshi) and LC1(75% Guangyi +25% Shengshi) were both the optional mixture combinations.In mixed grassland,the height of Shengshi was increased and that of Guangyi was decreased.And in all treatments,the average of leaf area index(LAI) of mixed grassland was lower than that of monocultured Guangyi grassland.Furthermore,the yield of mixed cut-grassland was more than that of monoculture.