| Gentiana straminea Maxim. is one of the most important varieties of local Chinese herbal medicinesin Gansu Province. Based on field trials, the floral characteristics of G. straminea, sexual breeding system,seed filling characteristics and the seed developing dynamic have been systematically studied in order toprovide the theoretical and technical basis for its breeding and the standardization seed harvest of the plant.The main conclusions are as follows:1. In the florescence maintaining30to40d, the blooming maintained5to8d for the single flowerand8to11d for the anthotaxy with3000grains of the average pollen. The pollen vitality was weak onthe first day of blossom and reached the maximum of86.76%after2d, and then showed a reduction trendgradually. Stigmas didn’t pollinate until they had peroxidase activity after2d, but the activity in thesecond days following blossom is weak. The stigma completely cracked after3days following blossomand had the strongest pollination ability. After that day the receptivity weakened gradually after4d untilthe crown closure. The flower has obviously combined ectopic flower with pistil dichogamycharacteristics.2. In terms of pollination, the stamen ripens earlier than protogynous when the flower diameter wasup to1.4to2.6cm. When the hybrid index is5, the stamens and pistils separated in time and space in theflowering process. Combined with the artificial bagged pollination test result, we can concluded that thebreeding system of G. straminea. could be attributed to partially self-incompatible, outcrossing andpollinators needed, in which phenomenon of apomixis didn’t exist and we could also get the results thatbumblebee is the most effective pollinators.3. In terms of the characters of grain filling, the seed fresh weight has reached its maximum on the34st day after flowering, and then it rapidly decreased to the level of its dry weight. The variation of itsdry weight has fitted to Logistic equation. In addition, grain dewatering rate continued accelerating withincreasing of grouting process, the water content showed a steady trend of first increased and thendecreased, which had been resulted from twice rainfall. The grain dry weight has showed a significantpositive correlation with fresh weight, dehydration rate and grain filling duration, while it has a significantnegative correlation with the water content.4. In terms of seed germination, maturity and weather condition of late filling stage had distinctlyeffect on the plant seeds. The seedling quality showed a significant positive correlation with fresh weightand grain filling duration, while it had a significant negative correlation with water content in seeds. Theseed did not have the ability to germinate within21d following blossom; after21d, both germination rateand germination potential increased significantly, reaching a higher levels on the43th day after blossom,and then had a decreasing trend because of rain, and it reached the maximum on the52th day.To sum up, the breeding system of G. straminea can be attributed to partially self-incompatible,outcrossing and pollinators needed. It showed a longer flowering duration and abundant pollens. Thetrend of capsule’s splitting (52to58d after flowering) showed that the seed matured when the seed colorbecame dark brown and luster at the end of the grain filling, indicating the optimal harvest time(September8to September14), in which water content in the seeds contained11.30%-17.29%. The seedsshould be harvested in batches with cotton or nylon bags according to the maturity. |
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