Q.P. van der Meer
Cytoplasmically (S-) determined male sterility in onions, found in California in 1925, was used for breeding hybrid varieties which have been appearing in the USA since the early 1940s. American hybrids excel in yield and/or quality. Hybrids also dominate the onion seed market at present in The Netherlands, U.K., and Germany, but they surpass open-pollinated varieties (OP) only by small percentages in yield and/or quality. Hybrid onions are lacking in countries such as Czechoslovakia, Egypt, and India because of the absence of the maintainer genotypes for male sterility. Views are presented on the relevance of hybrid breeding of tropical onion improvement, and options for onion improvement are included in this paper.

In the author's view, low priority should be given to breeding onion hybrids for the tropics while high priority should be given to the following:

  • collection, multiplication, and evaluation of a wide spectrum of tropical onion strains;
  • selection for improved characters in promising strains;
  • combining complementary promising strains and subsequent selection in resulting composites;
  • addition of individual superior characters from nonadapted varieties and closely related species;
  • improvement of multiplication methods for the central tropics (from 10° N - 10° S).

In the meantime, well-equipped institutions in or close to the subtropics (e.g., AVRDC and/or Rahuri) could pave the way for local hybrid breeding in the near future by:

  • analyzing tropical strains for frequencies of S, N, ms, and Ms genes; and
  • testing the male sterility in question for its thermostability in tropical conditions.
van der Meer, Q.P. (1994). ONION HYBRIDS: EVALUATION, PROSPECTS, LIMITATIONS, AND METHODS. Acta Hortic. 358, 243-250
DOI: 10.17660/ActaHortic.1994.358.40

Acta Horticulturae