Abstract

An experiment was conducted during 2017-18 at ICAR-National Research Centre for Grapes, Pune (Maharashtra) to study leaf micro-morphological traits such as leaf trichome density, leaf thickness, stomatal density, stomatal length, stomtal breadth, guard cell area, stomata opening and association of these traits with various scale of downy mildew resistance in twenty grape genotypes. Among the traits studied, the presence of leaf trichomes have justified downy mildew resistance partially only. But all the susceptible genotypes had lower trichomes density. The lower leaf trichomes are reported to be control by locus located on LG5. Traits like leaf thickness, stomatal density and time of stomatal opening have not shown significant relation with resistance. The moderate positive correlation was recorded for stomatal length (R = 0.708), stomatal breadth (R = 0.544) and guard cell area (R = 0.661) with resistance. Enlarge stomatal size provides larger area for zoospores to encyst and favours rapid spread of infection. The identification of such physical indicators responsible for resistance will be benefial in resistance breeding programmes for parental selection and progeny selection.