Effects Of Different Mating Systems On The Propagative Characteristics Of Medicago Sativa L. Cv. XinMu No.4

Medicago sativa L.cv. XinMu No.4 were used as materials in this experiment. Floral morphology, characteristics of pollination, flowering habits and seed setting characteristics were characterized, using the different isolation conditions and different pollination methods in or out of the net room, and the inbreeding(same pollination in one plant, cross pollination in one plant), and inter specific hybrid(Medicago falcate cross Medicago sativa, Medicago sativa cross Medicago falcata) were as research content. The effects of different pollination methods on the flowering habits and seed setting characteristics in Medicago sativa were explored, and the correlation between pollen dispersal period and floral morphology were researched as the same time, and also the pollen germination and pollen tube growth in two species of Medicago sativa under different mating systems were studied. The experimental results were as follows:1. In this experiment, floret development process of Medicago sativa was divided into six periods. Compared with the previous studies, the division is more detail, which is helpful for the study of pollination and fertilization of Medicago sativa L. The six periods were: I,upper petal slightly above the calyx. II, upper petal exposed out of the calyx. III, upper petal exposed out of the calyx entirely. IV, upper petal exposed out of the calyx entirely but wing flap was not expanded. V, upper petal exposed out of the calyx entirely and wing flap was expanded. VI upper petal flipped. In Medicago sativa, the pollen dispersd in period VI, and the pistils cracked in period V. When stamen pollens began to disperse, the flower bud length of Medicago sativa L was 7.09 ±0.09 mm, and when pistils began to crack, the flower bud length was 7.01 ±0.07 mm.2. There were significant differences in flowering habits of Medicago sativa between in the net room and out of net room. In the net room, development of Medicago sativa from budding to wilting lasted 52.5-88.5 hours and the flower bud lasted 36-72 hours after opening,whereas out of the net room, the development from budding to wilting lasted 18-22 hours and the flower bud lasted 2-6 hours after opening. The development of Medicago sativa from budding to stamen pollens dispersing needed 14.5-15 hours, and it needed just 0.5 hours from budding to pistils cracking.3. The rate of pod bearing under same pollination in one plant in Medicago sativa showed 4.96%, and the cross pollination in one plant showed 26.61%. The rate of pod bearing under intravarietal crossing in Medicago sativa showed 23.97%, and the rate of pod bearing under interspecific hybridization of Medicago falcata cross Medicago sativa and Medicago sativa cross Medicago falcata showed 27.95% and 20.47%, respectively.4. Cross pollination pollen germination and pollen tube growth rate is faster than self pollination, different mating patterns had significant difference in pollen germination and pollen tube development. The time from pollen germination to pollen tube into the embryo sac needed 25 hours in self- pollination, whereas the time from pollen germination to pollen tube into the embryo sac needed 20 hours in hybrid pollination.