INHERITANCE OF RESISTANCE TO CLUBROOT (PLASMODIOPHORA-BRASSICAE WOR) IN KALE (BRASSICA-OLERACEA SSP ACEPHALA L)

For kale (Brassica oleracea ssp. acephala L.), the inheritance of resi stance and that of tolerance to clubroot (Plasmodiophora brassicae) we re studied. Six homozygous lines belonging to the half marrow-stem and green curly kale groups were intercrossed in a diallel F1 mating desi gn. Inheritance of resistance was assessed from a glasshouse test on y oung plants and from a field trial on adult plants. A Disease Index wa s used to estimate the behaviour of each progeny. Tolerance to clubroo t was defined as the ratio of yield produced by a progeny on a clubroo t-infected part of the field compared with its yield on an uninfected soil. Resistance to clubroot on young and adult kales is mainly contro lled by genetic effects. The broad sense heritability assessments are greater than 0.8 for the 2 trials. Resistance inheritance is character ized by a predominance of additive genetic effects with incomplete dom inance. Yet, the additive components have less relative importance com pared to dominance effects in the inheritance of resistance of adult k ales (h2ns = 0.55 compared to 0.78 for young kales). Many dominant all eles control resistance. The phenotypic and genetic values calculated for resistance are not correlated with those of tolerance. The dominan ce genetic effects control a great part of the genetic variation for t olerance (h2ns = 0.16). Breeding programmes are proposed to increase c lubroot resistance level in the kale group. A maternal individual recu rrent selection on progenies could be undertaken.