Research on mechanical properties and chemical compositions of bottom stems of medicago sativa in harvesting period

Two species of Medicago sativa lower cellulose and Gannong No.3 stems were chosen to perform the biomechanical nature of forage stems by the electronic testing machine CMT2502 and X.H.ΠoHuhoκ method. The mechanical properties were measured and the cellulose, lignin and protein contents of forage stems in different conditions were tested, the relevant changing trends were studied with statistical software. The results indicated that, Medicago sativa stems have enough strength and good flexibility, the average maximum shearing force with the slippery angle of 30° in the two species are 77.07N-, 84.21N, respectively, the tensile Stress-Strain curve of bottom stems obeyed Hooke´s law, The cellulose, lignin and protein contents increased with the reduction of moisture content. In the two species, both the tensile strength and percentage of cellulose were negatively correlated with stem diameter, while a positive correlation was found between percentage of cellulose and tensile strength. The research demonstrated that the influence of cellulose content was greater than that of lignin content on stem tensile strength. The new breeding fine variety of Medicago sativa lower cellulose which with higher protein(3.55% in stems) was easier to harvest with machine because of similar strength, flexibility and shearing energy with Gannong No.3.