Study On The Forming Mechanism Of Legume Hard Seeds

Hard seeds are very common in many species of legumes. This thesis firstly analyzed the hard-seed forming process during the seeds development of Medicago falcata L. and Lespedeza davurica Schindler; then a feeding experiment with sheep, chicken and quail was conducted to investigate germination percentage change of 6 legume species seeds after ingestion. The results showed: (1)During the seeds development of M.falcata L. and L. davurica Schindler, seed size has varied from small to large, then from great to small; the moisture content of seeds dropped gradually, 45d after peak anthesis dropped to 6.9% and 10.3% respectively; fresh weight of seeds reached maximum prior to dry weight, 45d after peak anthesis dry weight and thousand-grain weight of seeds increased to the heaviest and tended towards stability; The electric conductivity of seeds decreased with days after peak anthesis, seeds attained physiological maturity at 45 days after peak blooming. The seed coats of M.falcata L. and L. davurica Schindler had a layer of palisade cells, there was a fissure on the hilum surface and the hilum consisted of two layers of palisade cells. With the maturity of seeds, the palisade cells became longer, from loosely arranged turned into neatly and tightly, formed water impermeable layer; and the two layers of palisade cells of hilum differentiated completely, linked so closely that the fissure was closed. At 30 days after peak anthesis, the germination percentage of M.falcata L. and L. davurica Schindler seeds reached 70.5% and 80% respectively, seed vitality index and seed germination index was higher than other periods; then with the maturity of seeds, hard-seed percentage increased and exceeded the increase of germination percentage, at 45 days after peak blooming reached 81% and 94% respectively. (2)The standard germination percentage of seeds recovered from the animal feces was significantly higher than the control (P<0.05), the animals with big size had relative strong digestion effect on seeds. Various digestion effect received by seeds in the body of animals could soften the hard seeds and improved the germination percentage of recovered seeds. The ingestion of seeds by wild animals had positive function to the forming of hard seeds: Hard seed characteristic in legumes might be a kind of beneficial biological adaptation which developed during the long-term coevolution with wild animals; it is a kind of special defense mechanism and had important ecological significance.