Drought Tolerance Studies in hirsutum Cotton Genotypes
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Date
2017-10
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University of Agricultural Science, Dharwad
Abstract
Experiment with 20 cotton (Gossypium hirsutum) genotypes planned for screening for water stress tolerance. Initially, laboratory screening for seed germination and seedling growth under different osmotic stress (using Polyethylene glycol-6000 solution) and seedling growth under different soil moisture levels (grown in polybags) were conducted during 2014-15 at ARS, Dharwad. The osmotic screening was done using PEG-6000 with different osmotic potentials viz., 0 MPa (control), -1.47 MPa (10 %) and -3.49 Mpa (20 %) and polybag growth study was conducted in rain out shelter with different field capacities moisture levels viz., 100, 50 and 25 per cent. Observations on germination percentage, root length, shoot length, root to shoot ratio, leaf proline and chlorophyll content were measured. From these studies, ten genotypes viz., BS-37, BS-39, ARBH-1352, GBHV-182, PH-1060, SCS-1062, TCH-1777, GSHV-169 and AKH-09-5 were identified as drought tolerant. These ten identified genotypes along with two checks (RAH-100 and LRA-5166) were subjected for field performance for two seasons.
The selected 12 cotton genotypes were further evaluated in field condition during kharif 2015-16 and 2016-17 under rainfed and need based irrigated (flowering and boll development) conditions. Observations on morpho-physiological, phenological, biochemical, yield and yield components were recorded. The pooled data of two years was analyzed under split plot design. Significantly higher seed cotton yield was recorded under rainfed condition as compared to irrigated condition. Mainly relative water content (-10.55), cell membrane stability (15.61 %), specific leaf weight (-4.52 %), excised leaf water loss (16.48 %), stomatal frequency (16.72 %), trichome density (-29.91 %), chlorophyll (7.41 %), proline (-75.00) and phenol (-9.61) content which indicates the tolerance of these genotypes to water stress condition .
Based on the criteria of least per cent reduction in maximum number of parameters, five cotton genotypes GSHV-169, BS-37, BS-39, AKH-09-5, ARBH-1352 were identified as more tolerant to water stress.