| Summary: | 碩士 === 國立屏東科技大學 === 熱帶農業暨國際合作系 === 102 === Melastomataceae is a large family of tropical and subtropical plants of about 166 genera worldwide and 11 genera native to Taiwan. However, only four cultivars have been trading commercially in the past few years. This study was conducted to determine the crossing feasibility within this family, which aims at increase genetic variation and breeding for ornamental novel varieties and propagation via seeds for establishment. Five plant resources (Dissotis rotundifolia (Sm.) Triana, Medinilla hayataina Keng. Tibouchina granulosa ‘Kathleen, Tibouchina semidecandra (Mart. &; Schrank ex DC.) Cogn. and T. urvilleana (DC.) Cogn.) in Taiwan were used as plant materials. Pollen viability and germination tests were carried out to evaluate the best time to harvest fresh pollen grain. Self-pollination was conducted to investigate self-compatibility. The species which were unable to set its fruits were discarded from hybridization scheme. Seed germination tests were conducted to determine seed fertility from selfs and F1 hybrids. Results from pollen viability test illustrated the best time of collected fresh grain for the highest potential pollen viability were at 7:30-8:00 a.m. for T. granulasa (90%), D. rotundifolia (99%) and T. urvilleana (16%) were at 9:30-10:00 a.m., and M. hayataina (40%) and T. semidecandra (90%) at 11:30-12:00 a.m. The best potential pollen germination rate of interaction between time and sucrose was at 9:30-10:00 a.m. used 0% sucrose concentration for T. granulosa (70%) and T. urvilleana (9.3%). At 11:30-12:00 a.m. the pollen germination rate of 0% sucrose treatment was D. rotundifolia (99%) and 5% sucrose for M. hayataina (28%) and T. semidecandra (67%). Fruit setting from selfing of D. rotundifolia, M. hayatina, T. granulosa and T. semidecandra were 48%, 52%, 52%, and 88% respectively. The seed germination rates were 8% (T. granulosa), 24% (T. semidecandra), 69% (D. rotundifolia), and 97% (M. hayataina). However, T. urvilleana was unable to set any fruit; therefore, this species was excluded from male parental of interspecific hybridization. Sixteen potential cross-pollinations were conducted. Four hybridizations included T. granulosa X T. semidecandra, T. semidecandra X T. granulosa, T. urvilleana X T. granulosa and M. hayataina X T. granulosa were capable to form seed pod of 8%, 12%, 12% and 16% respectively. The average seed germination rates of these four hybrids were 6%, 87% 35%, and 57% respectively. Additionally, the F1 hybrid plantlets of T. semidecandra X T. granulosa had six different leaf morphologies as compared to its parents. T. granulosa X T. semidecandra had five new leaf characteristics. M. hayataina X T. granulosa and T. urvilleana X T. granulosa two leaf character variations were recorded. Ultimately, reciprocal crossed between T. semidecandra X T. granulosa were able to create more variation of totally different leaf morphologies with two (T. granulosa X T. semidecandra) and three (T. semidecandra X T. granulosa) traits from their parents. Additionally, increasing genetic variation was successful from interspecific hybridization between T. granulosa and T. semidecandra and propagated by seed.
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