Preliminary Study On The Reproductive Biology Of Desmodium Styracifolium(Osbeck.) Merr.

Desmodium styracifolium is a perennial herb of Leguminosae, and their branches and leaves are widely used in China. And they are distribute in Guangdong, Guangxi, Hunan provinces of China. All of the Chinese drug of “Xiao shi yin”, “Xiao yan li dan tables”, “Xiao shi table” and “Herba Lysimachiae granules” were mainly make of D. styracifolium. Withthe increasing demand, the wildresources of D. styracifolium were in short supply, and the resources will be replace by cultivated. A large cultivation were found in Guangdong, Guangxi and Hainan provinces. D. styracifolium production with seeds, but seeds were in small size, and seed maturity did not uniform, so its quality have a direct impact on plant growth and affect the quality of medicinal materials. Therefore, this paper carry out experiments to study flower bud differentiation,blossom and fruiting features,pollenactivity and storage conditions,pollination mechanismand pollinating insects, breeding system of D. styracifolium for further study of reproductive biology, increasing quality and yield of herbs and seeds, and the new varieties cultivation. The main results are presented as follows: 1. Flower bud differentiation: the whole flower bud differentiation period can divided into five periods: 1. Flower bud differentiation; 2. Inflorescence differentiation; 3. Floret primordium differentiation; 4. Floral organ differentiation; 5. Inflorescence formation stage; according to the morphology of the flower bud differentiation. Floret primordium differentiation were sequentially from down to up. Differentiation of the adjacent flower organs were usually in turn backward 1 or 2 differentiation periods. The differentiationofstems were 1 or 2 periods earlier than lateral branches. 2. Blossom and fruiting features:The flower bisexual. The blossom peak time of D. styracifolium was from 9:30 to 11:00, and flowering amount of plants accounted for 70.90%. There were about 200 to 699 inflorescences in each plant. The numbers of daily blossom showed normal distribution patterns. Flowering time was about 45 days, and single one was one day. The buds number of terminal inflorescence were 27 % more than axillary inflorescences and the pods number were 20.3 %, and the seeds number were 36.20 % more thanaxillary inflorescences, those three indexes were reached theextremely significant difference(P<0.01). The seed set ratio of terminal and axillary inflorescence were 91.95 %, 93.87 % respectively, were not reached significant difference(P<0.05). There were four kinds of color variations(red, pink, green and light green) in D. styracifolium. 3. Pollen Viability and Storage Methods: Vitro culture methods were applied to the determination of different storage conditions on pollen viability. The optimal medium of pollen germination and pollen tube growth was the buffer containing 15 % sucrose + 0.01 % H3BO3 + 0.09 % Ca(NO3)2·4H2O + 0.01 % MgSO4·7H2O, the germination rate was 93.57±1.85 % and pollen tube length was 541.7 μm after cultured 2 hours. Under suitable culture conditions, cultured for 2 hours was the optimal culture time for pollen germination. The pollengerminationrate in four degrees Celsiusconditions was higher than othersstorage conditions,so four degrees Celsiuswas the beststorage conditions for D. styracifolium, and the pollen germination rate was 53.38±4.49 % for 168 hours, which wassignificantlyhighest than therate of germinationof othersstorageconditions. Thepollen gerrminationbeforeone hour for blossom was 30.20 + 1.57 %, 74.30 +1.57 % before 0.5 h, and93.57 +1.85 % when flowers were about to open. Therefore the optimalacquisition time for pollen was when theflowers were about to open. 4. Pollination mechanism and pollinating insects: D. styracifolium were characterized by an explosive pollination mechanism. This mechanism cannot spontaneously active, must rely on pollinators visitingflowers and given exerting pressure on the flower. The floral parts cannot return to their original positions after activated. Almost all of the pollen were deposition when the pollinators first visiting the flower. The pollinators are the bees of Apidae and Megachilidae from Dipter, Amegilla( Zonamegilla)parhypate Lieftinck, Megachile(Callomegachile) umbripennis Smith, Megachile(Eutricharaea) conjunctiformis Yasumatsu, Megachile(Eutricharaea) abluta Cockerell and Megachile sp. were most common, the Ischiodon cutellaris Fabricius and Paragus crenulatus Thomson of Syrphidae from Hymenoptera were sew Occasionally. 5. Reproductive biology system: Stigmas had receptivity 1 hour before blossom and after blossom in 8 hours. The P/O was 8000±1225, the OCI was 4, and results of bagging experiment showed that the breeding system of D. styracifolium was mainly self-pollination, cross-pollination. The above results showed that the breeding system of D. styracifolium was mainly self-pollination, cross-pollination and pollinator were needed.