Genetic variability of mulberry (Morus spp.) germplasm against powdery mildew (Phyllactinia corylea) and identification of high resistance genotypes

The disease response and magnitude of genetic variability of 85 mulberry genotypes of different agroclimatic origin was studied against powdery mildew caused by Phyllactinia corylea. It was observed that there was a wide variation of disease severity among the test genotypes. Australian and France originating genotypes were found to be highly resistant to mildew followed by of Thai and Italian origin. Genotype wise, the lowest mildew disease severity was recorded in Thailand lobed]) followed by M. malticaulis, M. australis and Italian. Genetic analysis of disease severity revealed that the estimate of phenotypic coefficient of variation (PCV) and genotypic coefficient of variation (GCV) were high and that PCV was greater than GCV. High estimate of heritability coupled with high genetic advance showed that the mildew disease resistant trait is governed by an additive gene action. Hence the highly resistant mulberry genotypes identified may be exploited through hybridisation followed by selection under epiphytotic conditions for the improvement of disease resistant traits in mulberry.