partial diallel study of powdery mildew resistance in six apple cultivars under three growing conditions with different disease pressures

• Published in: Euphytica Vol. 148; no. 3; pp. 235 - 242
• Main Authors: Bus, V.G.M, Ranatunga, C, Alspach, P.A, Oraguzie, N.C, Whitworth, C
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer 01.04.2006; Springer Nature B.V
• Subjects: Agronomy. Soil science and plant productions; Airborne microorganisms; apples; Biological and medical sciences; Climatic conditions; crop quality; Cultivars; diallel analysis; disease resistance; Food quality; fruit quality; Fruits; Fundamental and applied biological sciences. Psychology; general combining ability; genetic correlation; Genetics; Genetics and breeding of economic plants; genotype-environment interaction; hybridization; Malus; Malus domestica; phenotypic correlation; Podosphaera leucotricha; powdery mildew; Seedlings; specific combining ability; Varietal selection. Specialized plant breeding, plant breeding aims; New Zealand; Production quality; Plant pathogen; Mycosis; Podosphaera leucotricha; powdery mildew resistance; Quantitative character; Rosaceae; Genetic parameter; Malus domestica; Genetic determinism; Fungi; Dicotyledones; Angiospermae; Ascomycetes; Fruit tree; fruit quality; Thallophyta; Fruit; Diallel analysis; Fungus resistance; Infection; Combining ability; Apple; general combining ability; specific combining ability; Genetic improvement; Spermatophyta; genetic correlations; Cultivar
• ISSN: 0014-2336; 1573-5060
• DOI: 10.1007/s10681-005-9014-2

The suitability of large-fruited apple cultivars as alternative donors of powdery mildew resistance to the crabapples carrying major gene resistances was assessed. Five accessions with varying levels of mildew resistance ('Dülmener Rosen', 'Liberty', 'Sciros', 'Prima' and 'Red Delicious') and one susceptible cultivar ('Cox's Orange Pippin') were mated in a partial diallel design, and sub-sets of each seedling family were evaluated for three years at three New Zealand sites (Havelock North, Riwaka and Clyde) with different climatic conditions. There was a high correlation among the powdery mildew susceptibility scores of the individual seedlings over the three years, but disease levels varied among sites, with those at Clyde being the highest. All accessions with some resistance were found to confer additive resistance to their progenies to varying degrees depending on the climatic conditions of the sites, but findings suggest that progeny selection at Clyde will be sufficient for breeding purposes. The performance of the cultivar itself was not necessarily a good predictor of the level of resistance conferred to its progenies. The mostly negative genetic correlations between powdery mildew scores and fruit quality attributes suggest that selecting for powdery mildew resistance and desirable fruit quality traits may not be difficult. However, a larger number of families may be needed for more precise estimates of the genetic correlations to strengthen confidence in this conclusion.[PUBLICATION ABSTRACT]