The Breeding for Development of Rhododendrons and Azaleas with Heat Resistance and New Flower Colors

有些鳞片杜鹃花（lepidote rhododendron， LR）的形态特征与常绿杜鹃花（Evergreen Azaleas， EA）相似，其花色呈极好的蓝色。然而，它们的根本缺陷是缺乏耐热性。此外，交叉不相容和/或杂交不育是经常遇到的。对26个品种进行了不完全双等位基因杂交。从杂交能力、耐热性和观赏性等方面筛选出2个品种和7个栽培品种作为选育材料。利用这些材料进行了进一步的杂交，一些LR与托卡拉群岛的耐热EA R. Eriocarpum进行了初步杂交，取得了成功。采用高效液相色谱法对蓝色、紫色、粉色、玫瑰和红色杜鹃花色素成分进行了比较。花青素的羟基化和甲基化、黄酮醇总量及其甲基化、花青素与黄酮醇的共色素化是青色发育的重要因素，但花青素的羟基化作用似乎更为突出。在分析过程中，还发现在一些玫瑰和红杜鹃花中存在一种未知的黄色色素，从而提出了另一种强化黄色花色的育种方法的可能性。采用EA/落叶杜鹃花（DA）和LR/ eleepidote Rhododendrons （ER）亚属间杂交，培育出具有强黄色和其他观赏性状的杂交品种。ER × DA和ER × LR杂交种子萌发，而LR × DA、EA × DA和LR × ER正常大小杂交种子不萌发。此外，在黄色LR内的杂交中发现了相当严重的种间屏障。提出了多倍体育种的必要性。在塑料房内筛选了44,665株ER幼苗的耐热性。通过选择合适的亲本材料、重复杂交和严格的后代选择，可以提高耐热性。少

Some lepidote rhododendrons (LR) which have morphological characteristics similar to Evergreen Azaleas (EA) have excellent blue flower colors. Their fundamental defect is, however, their lack of heat resistance. Moreover, cross-incompatibility and/or hybrid sterility are frequently encountered. Incomplete diallele crosses using 26 species and cultivars were conducted. Two species and 7 cultivars were selected as promising breeding materials from their cross-ability, heat resistance, and ornamental characteristics. Further crosses using these materials were conducted, in which initial crosses between some LR and R. Eriocarpum, a heat resistant EA from Tokara Archipelago, were successful.Pigment components of blue, purple, pink, rose and red rhododendrons were compared using HPLC. Hydroxylation and methylation of anthocyanin, total amount of flavonol and its methylation, and copigmentation between anthocyanin and flavonol were important factors towards development of bluer hues, although … More action of hydroxylation of anthocyanin seemed to be most prominent. In the course of this analysis, an unknown yellow pigment was also revealed to be present in some rose and red rhododendrons, The possibility for another breeding approach to intensify yellow flower color was thus suggested.Intersubgeneric crosses among EA/Deciduous Azaleas (DA) and LR/Elepidote Rhododendrons (ER) were implemented to develop hybrids with intense yellow color and other ornamental characteristics. Hybrid seeds from ER x DA and ER x LR germinated, but normal sized hybrid seeds from LR x DA, EA x DA and LR x ER did not germinate. In addition, a fairly severe interspecific barrier was found in crosses within yellow LR. The necessity for polyploid breeding is suggested.About 44,665 ER seedlings were screened for heat resistance in a plastic house. It was suggested that improvement of heat resistance is possible through selection of appropriate parental materials, repetition of crosses, and strict progeny selection. Less