Biodiv Sci ›› 2019, Vol. 27 ›› Issue (3): 327-338.DOI: 10.17520/biods.2018345

• Review • Previous Articles     Next Articles

Progress on the fertility of Rhododendron

Zhuang Ping()   

  1. West China Subalpine Botanical Garden, Institute of Botany, Chinese Academy of Sciences, Dujiangyan, Sichuan 611830
  • Received:2018-12-29 Accepted:2019-03-05 Online:2019-03-20 Published:2019-04-09
  • Contact: Zhuang Ping

Abstract:

To provide a reference for researchers, achievements and progress in recent years on the fertility of Rhododendron in China and abroad were summarized. (1) There are polyploidy in subgen. Rhododendron and subgen. Pentanthera, and even various ploidy in the same species. (2) Under natural pollination, in addition to the common intra-specific cross- and self-fertilization, inter-specific cross-fertilization was also widespread in subgen. Hymenanthes, subgen. Rhododendron and subgen. Tsutsusi. There were also some cases of inter-subsection cross. (3) Self compatibility (SC) and self incompatibility (SI) simultaneous exist in Rhododendron. Subsect. Fortunea shows all types from self sterile to high fertility. Self incompatibility often occurs in subgen. Tsutsusi and subgen. Azaleastrum and although self-fertilization is usually considered to be a passive adaptation, it could be an active response to the adverse environmental conditions for a few local species. (4) Through artificial crosses between different taxa (subgenera, sections and subsections), the inter-specific crossability was obviously relevant to the relationship of phylogenetic development and chromosomal ploidy of parents. This was reflected in the changes of indices of compatibility in different phases of development and was discovered that hybridization was easier between distant subgen. Hymenanthes and subgen. Rhododendron. There were also some cases of compatibility such as the reciprocal crosses between subgen. Hymenanthes and subgen. Tsutsusi, subgen. Tsutsusi and subgen. Rhododendron as well as the unidirectional compatibility between subgen. Tsutsusi and subgen. Pentanthera, subgen. Hymenanthes and subgen. Pentanthera, subgen. Azaleastrum and subgen. Rhododendron. (5) It leads to increases in the fertility and development from bidirectional fertility to unidirectional sterility and then bidirectional sterility in inter-specific cross as SI parents get involved.

Key words: Rhododendron, polyploid, pollination biology, self-fertilization, hybridization, compatibility, fertility