Interspecific Hybridization and Effects of Shading on Growth of Hydrangea chinensis Maxim. and H. macrophylla Thunb.
| Autor: | Tai-Yin Chen, 陳岱吟 |
|---|---|
| Rok vydání: | 2019 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 107 The genus Hydrangea is one of the major ornamental flowers. Among them, H. macrophylla Thunb. is the most popular species because of its large and bright- color sepal. Evergreen H. chinensis which grown vigorously in low attitude hillside, is tolerant to environmental stresses and having earlier flowering time. The pollen viability and interspecies crossing between H. chinensis, H. macrophylla ''Leuchtfeuer'' and. ''Freudenstein'' for selecting off springs with good flower shape of color that will be used as pot flowers or landscaping plants. The results showed that H. chinensis and H. macrophylla ‘Leuchtfeuer’ had better pollen germination with 5% sucrose-medium, the germination rate were 21.5% and 10.6%, respectively. H. macrophylla ''Freudenstein'' had higher pollen germination rate cultivated in 10% sucrose-medium valued 83.5%. The optimum temperature for H. chinensis and H. macrophylla ‘Leuchtfeuer’ pollen germination was at 30℃, and the germination rate was 86.9% and 17.0%, respectively. The optimum temperature for the pollen of H. ''Freudenstein germinate was at 25℃ valued 61.6%. In the selfing of three species, the fruit set of H. chinensis was 77.9%, H. macrophylla ''Leuchtfeuer'' and ''Freudenstein'' were without fruiting. Regarding to reciprocal crossing experiment, the H. chinensis as a female parent crossed with ''Leuchtfeuer'' and ''Freudenstein'' resulted in 40.9% and 73.2% fruiting rates, and each capsule contained 70.5 and 109 seeds. The germination rates of hybridized seed were 31.8. % and 58.9%. The H. macrophylla ''Leuchtfeuer'' and. ''Freudenstein'' crossed with H. chinensis had 37.0% and 53.0% fruiting rate with 4.1 and 47.5 seeds per capsule. Their hybrid seeds had 31.8% and 58.9% germination rates, respectively. Among interspecies hybridization there were better offsprings with plant morphology, sterile flower size r and total shoot number from H. chinensis as a hybrid parent. The flowering period of the hybrid offspring began flowering at the end of March, the excellent traits of early flowering was from H. chinensis. H. chinensis and H. macrophylla ''Leuchtfeuer'' were grown under four control treatmenst, the average light intensities were 505, 202, 60, and 14 μmol·m-2·s-1 at noon, respectively. H. chinensis still maintains normal growth at about 440 and 200 μmol·μmol·m-2·s-1 light intensities at noon, and is gradually domesticated under 50% shading. H. macrophylla ''Leuchtfeuer'' is moderately shady in summer (average noon The luminosity is about 200 μmol·m-2·s-1), which has better growth performance, large leaf area and plant height, and has the highest light saturation point and maximum photosynthesis rate. Over-shadowing (average luminosity below 60 μmol·m-2·s-1) has the lowest shoot length, plant height, leaf dry weight, and maximum photosynthesis rate, indicating excessive shading affecting growth. |
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