Studies on Intersubgeneric Hybridization ability between Evergreen Rhododendron varieties and native Rhododendron decorum Franch.

Abstract

The horticultural varieties of the evergreen Rhododendron 'Sima,' 'Yin Taohong' and 'Little Taohong' were used as the maternal lines, and the wild Rhododendron decorum Franch. was used as the paternal line for intergeneric crosses. Moreover, the horticultural varieties within the evergreen Rhododendron were also used as controls to study the effect of different pollination methods on hybrid compatibility. After the pollination, the rates of ovary swelling and fruit bearing, numbers of capsule seed, 1,000 seed weight of hybrid seeds, and the rates of germination and green seedlings were examined to comprehensively evaluate the degree of hybrid ability. Simultaneously, the pollen tube growth, fertilization, and hybrid embryo growth and development through the pollen tube were observed by fluorescence microscopy and paraffin sectioning to study the compatibility and histological mechanism of intersubgeneric hybridization between horticultural varieties of the evergreen Rhododendron and Rhododendron decorum Franch. This study provided a scientific basis for intergeneric hybridization breeding between the evergreen Rhododendron and the Rhododendron decorum Franch..