EVALUATION OF DROUGHT TOLERANCE IN NEW COTTON CULTIVARS USING STRESS TOLERANCE INDICES

Abstract

Drought is a wide-spread problem seriously influencing production and quality of
cotton (Gossypium hirsutum L.), but development of resistant cultivars is hampered
by the lack of effective selection criteria. The objective of this study was to
evaluate the ability of several selection indices to identify drought tolerant cultivars
under different environmental conditions. Thirteen cotton cultivars were evaluated
under both moisture stress (2016) and non-stress (2013) field environments using a
randomized complete block design for each environment. Six drought tolerance
indices including stress susceptibility index (SSI), stress tolerance index (STI),
tolerance index (TOL), mean productivity (MP), geometric mean productivity
(GMP) and mean harmonic productivity (HMP) were used. The significant and
positive correlation of yield of genotype under non-stress condition (Yp) and MP,
GMP and STI showed that these indices were more effective in identifying high
yielding cultivars under different moisture conditions. The results of calculated
gain from indirect selection in moisture stress environment would improve yield
better than selection from non moisture stress environment. Coton breeders should,
therefore, take into account the stress severity of the environment in choosing an
index. The varieties Viki and Avangard-264 had the highest yields under non-stress
conditions. Vega and Chirpan-539 varieties had a low yield potential and showed a
high stress tolerance to drought.