Drought Tolerance Studies in hirsutum Cotton Genotypes

Abstract

Experiment with 20 cotton (Gossypium hirsutum) genotypes planned for newlinescreening for water stress tolerance. Initially, laboratory screening for seed germination newlineand seedling growth under different osmotic stress (using Polyethylene glycol-6000 newlinesolution) and seedling growth under different soil moisture levels (grown in polybags) newlinewere conducted during 2014-15 at ARS, Dharwad. The osmotic screening was done newlineusing PEG-6000 with different osmotic potentials viz., 0 MPa (control), -1.47 MPa (10 newline%) and -3.49 Mpa (20 %) and polybag growth study was conducted in rain out shelter newlinewith different field capacities moisture levels viz., 100, 50 and 25 per cent. Observations newlineon germination percentage, root length, shoot length, root to shoot ratio, leaf proline and newlinechlorophyll content were measured. From these studies, ten genotypes viz., BS-37, BS- newline39, ARBH-1352, GBHV-182, PH-1060, SCS-1062, TCH-1777, GSHV-169 and AKH- newline09-5 were identified as drought tolerant. These ten identified genotypes along with two newlinechecks (RAH-100 and LRA-5166) were subjected for field performance for two newlineseasons. newlineThe selected 12 cotton genotypes were further evaluated in field condition newlineduring kharif 2015-16 and 2016-17 under rainfed and need based irrigated (flowering newlineand boll development) conditions. Observations on morpho-physiological, newlinephenological, biochemical, yield and yield components were recorded. The pooled data newlineof two years was analyzed under split plot design. Significantly higher seed cotton yield newlinewas recorded under rainfed condition as compared to irrigated condition. Mainly newlinerelative water content (-10.55), cell membrane stability (15.61 %), specific leaf weight newline(-4.52 %), excised leaf water loss (16.48 %), stomatal frequency (16.72 %), trichome newlinedensity (-29.91 %), chlorophyll (7.41 %), proline (-75.00) and phenol (-9.61) content newlinewhich indicates the tolerance of these genotypes to water stress condition . newlineBased on the criteria of least per cent reduction in maximum number of newlineparameters, five cotton genotypes GSHV-169, BS-37, BS-39, AKH-0