野生杜鹃杂交亲和性及适宜的评价指标

Cross-compatibility of wild Rhododendron and the effective evaluation indicators

关键词:  杜鹃, 杂交亲和性, 结实性, 评价指标

Key words:  Rhododendron, cross-compatibility, fruitfulness, evaluating indicator

摘要:

以映山红和马银花为母本,映山红亚属、羊踯躅亚属、杜鹃亚属、常绿杜鹃亚属以及马银花亚属的5个亚属16个中国野生杜鹃种为父本进行杂交授粉,统计子房膨大率、坐果率和种子萌发率,分析杜鹃属植物远缘杂交的亲和性,探讨其杂交亲和性适宜的评价指标。结果表明:映山红作为母本,与同亚属的杜鹃杂交亲和性较好,与其它亚属的杜鹃种的杂交亲和性存在显著的亚属间和种间差异; 而马银花作为母本,与同亚属的西施花进行杂交,未获得杂交果实和种子,但与杜鹃其它亚属种的杂交,部分杂交组合显示出较好的杂交亲和性。这一结果表明,映山红作为母本,与马银花相比,有着较好的杂交亲和性,并且杜鹃属植物的杂交亲和性与目前杜鹃分类体系中的亲缘关系并没有直接关系。进一步的数据分析表明,子房膨大率与坐果率、坐果率与蒴果平均种子数之间呈显著正相关,但子房膨大率与果实内种子数无直接相关性; 花粉活力(大于15%)、父母本花柱长度比(在0.50～2.12范围内)与子房膨大率等亲和性指标无显著相关性。

Abstract:

Wild Rhododendron species are mostly distributed in high mountains, they favor cold environmental conditions, and high temperature has been the primary obstacle to cultivate them in most cities of China. In this study, R. simsii and R. ovatum with higher tolerance to heat stress were used as female parents, and crossed with sixteen wild Rhododendron species from subgen. Tsutsusi, subgen. Pentanthera, subgen. Rhododendron, subgen. Hymenanthes and subgen. Azaleastrum in order to breed new varieties with stronger heat resistance and higher ornamental value. The ovary-swelling rate, fruit-bearing rate and germination rate of hybrid seeds were investigated, the cross-compatibility among wild Rhododendron species and the effective evaluation indicators of cross-compatibility were discussed according to ovary-swelling rate, fruit-bearing rate and germination rate of hybrid seeds. The results showed that R. simsii as female parent had higher cross-compatibility than R. ovatum. When R. simsii was crossed with other species from the same subgenus, the cross-compatibility was higher. However, when R. simsii was crossed with the male parents from different subgenus, the cross-compatibility of these different cross combinations was obviously different. On the other hand, when R. ovatum was used as female parent, the hybridization affinity was not affected heavily by phylogenetic relationship. R. ovatum was crossed with R. ellipticum from the same subgenus, ovary-swelling rate was 43.4%, but fruit-bearing was not found, but when it was crossed with other species from different subgenra, some cross combinations had better cross-compatibility. Further data analysis indicated that there were positive correlations between ovary-swelling rate and fruit-bearing rate, between fruit-bearing rate and the number of seeds per capsule, but there was not significant correlation between ovary-swelling rate and the number of seeds per capsule. No direct connections were found between pollen viability(above 15%), SLR(male/female style length ratio)(0.50-2.12)and cross affinity.