Identifying drought tolerant cotton (gossypium hirsutum l.) genotypes by physiological and molecular approaches
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Date
2013
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UAS Dharwad
Abstract
A field experiment was conducted during 2011-12 for the evaluation drought
tolerance using thirty Gossypium, hirsutum L. genotypes in RBD design at ARS Dharwad
and ARS Annigeri. Ten best (CPD-750, Sahana, ARB-9701, CNH-120MB, GIHV-218, BS-
279, RAH-101, GJHV-477, F-2228 and KH-155) and two least (L-761 and LH-2076)
performed genotypes were selected from these experiments based on drought tolerant
physiological traits viz. SLW, water potential, SPAD values, gas exchange parameters and
yield.
Simultaneously 600 cotton germplasms lines were also evaluated for drought
tolerance by physiological traits at ARS Dharwad. Based on the SPAD, SLW and gas
exchange parameters 24 germplasm lines were showed significantly on par for the most of
the physiological traits.
During 2012-13, the selected twelve genotypes were evaluated for performance under
different concentrations of PEG-6000 osmotic solutions at germination stage by slanting
glass plate technique. The germination %, shoot length, seedling vigour index and shoot
vigour index decreased as the PEG 6000 concentration increase from 0% to 27% in all
genotypes, while the root length and root: shoot ratio increased. These genotypes were further
evaluated at rain out shelter for drought tolerance by morphological, physiological,
biophysical, biochemical, root architecture (length, volume and lateral roots) yield, yield
components and fibre properties. The genotypes viz. CPD-750, Sahana, ARB-9701, CNH-
120MB, GIHV-218, and BS-279 were found relatively drought tolerant. Further these twelve
genotypes were studied for genetic diversity study using 79 cotton specific RAPD molecular
markers. There was 79.56 per cent genetic polymorphism/diversity. The primers OPI 4 and
OLIGO 652 amplified 800 bp and 400 bp respectively were specific to relatively drought
tolerant genotypes. The dendrogram revealed that the primers were able to group the
genotypes in to three major clusters. From the overall present investigation, the genotypes viz.
CPD-750, Sahana, ARB-9701, CNH-120MB, GIHV-218, BS-279 and RAH-101 were
identified as drought tolerant lines.