Fundamental Study On Cross Breeding Of Ginkgo Biloba L.

As far as the diversity of forestry ecology system was concerned, the aim of study was to cultivate good leaf-utilization and wood-utilization Ginkgo cultivars. In two years, pollens of excellent father trees from various areas were gathered and cross with excellent mother trees of same cultivars and different cultivars, therefore, amount of whole-sib families' seeds were obtained. In controlled pollination experiment, appearances and shapes of different male tree's pollens had been studied, and the characters of hybrid seeds were also investigated. Furthermore, Fl progeny trials of one-year seedlings and two-year seedlings were made. Based on the data of the experiments, this paper made a fundamental study on cross breeding of Ginkgo Biloba L. At last, multiple-traits related to leaf-utilization and wood-utilization were chosen to made comprehensive evaluations and seedling selections by method of R-mode factor analysis and system cluster analysis. The main conclusions can be drawn as follows:1. Pollens obtained from different male trees located in different areas showed slight differences in appearance. Length, width and length to width of pollens from various father trees were significantly different. Pollens of thousand-year old tree in Rugao city of Jiangsu Province was the biggest in all subjects.2. Impact on the characters of hybrid seeds of mother trees was greater than father trees'. Different father trees' hybrid seeds had no significant difference in seed length, seed width, seed thickness, seed length to width, seed thickness to width, produced rate of kernel, hundred seeds' weight, germinative rate and fruit handle length. The controlled pollinated seeds were bigger than freely pollinated seeds in seed length, seed width, seed thickness, produced rate of kernel, hundred seed weight and germinative rate.3. Fl hybrid seedlings of different parents had significant variances in seedling's height, diameter, biomass, leaf morph and leaf yields. Branch length, branch diameter and water content of seedlings were also varied in different hybrids of Taixing two-year seedlings. Variance analysis showed that the controlled pollinated hybrids were better than freely pollinated hybrids in seedling's height, diameter, biomass, leaf morph and leaf yields.4. Fl hybrid seedlings of different parents had significant variance in chlorophyll content, flavonoids cpntent, ginkgolides content, photosynthesis rate and transpiration rate. Totally, mother tree's impact on the physiology properties of hybrid seedlings is greater than father tree's. The controlled pollinated filial generation is better than freely pollinated filial generation in physiology properties.5. Wood density, fiber width, fiber length to width of Taixing two-year hybrid seedlings had no significant variances, while fiber length, microfibril angel and water content of wood showed significant variances.6. Investigations about fitness and phenophase of different hybrids showed that thecontrolled pollinated filial generations were not so good as freely pollinated filial generations. The former seedling survival rate was lower than the latter, diseased seedling rate was higher than the latter.7. Multiple-traits comprehensive evaluations of leaf-utilization cultivars by the method of R-mode factor analysis showed that Taixing hybrids JY2, JY1, NL3 and NL2 were better options in leaf-utilization breeding, while Pizhou hybrids GZxXiaoyuanzi, GZxMaling, NJxXiaoyuanzi and FJxXiaoyuanzi were also valuable in leaf-utilization breeding.8. Multiple-traits comprehensive evaluations of wood-utilization cultivars by the method of R-mode factor analysis showed that Taixing hybrid NL2 was optimistic options in wood-utilization breeding, while Pizhou hybrids GZxDafezhi, GZxMaling were also valuable in wood-utilization breeding.