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Genetic variation for combining ability in tropical cauliflower populations

W.R. Maluf^I; M. Toma-Braghini^I; R.D. Corte^I; L.S. Caldas^I; H. Ikuta^II

^IBioplanta Tecnologia de Plantas S.A., Caixa Postal 1141, 13100 Campinas, SP, Brasil. Send correspondence to W.R.M.
^IIDepartamento de Genética, ESALQ, Universidade de São Paulo, Mogi das Cruzes, SP, Brasil

ABSTRACT

Two different seed parent populations of tropical cauliflower Brassica oleracea var. botrytis were considered in this study: clones selected from the open pollinated cultivar Piracicaba Precoce (CFP), and heat tolerant male sterile (HTMS) clones selected from (male-sterile Terezópolis Gigante x CFP) F₂. Each population was testcrossed to two different testers: population GJ and clone NTCF-12 for the former seed parent, and populations CFPcom and GJ for the latter. There was considerable variation among the testcrosses for the traits considered. NTCF-12 had a greater frequency of recessive (unfavorable) alleles than GJ for curd diameter (DIAM), weight (WEIGHT), quality (HQI) and subjective disease rating (SDR), but not for EARLINESS; accordingly, NTCF-12 is superior to GJ as a tester of combining ability of CFP clones, but inferior to GJ as a pollinator in the direct development of new hybrids. CFP clones with superior hybrid performance in combination with NTCF-12 will also produce superior hybrids with GJ. Likewise, GJ is superior to CFPcom as a tester of combining ability of HTMS clones, but inferior to CFPcom for direct use in commercial hybrid combinations. HTMS clones that produce superior hybrids with GJ will also produce superior hybrids with CFPcom. The hybrid means and the genetic coefficients of variation for combining ability suggest that good commercial hybrids can be developed from both seed parent populations and both of their respective testers.

Keywords: genetic; variation; combining; ability; tropical; cauliflower; populations.

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