Investigation and selection index for drought stress in durum wheat (Triticum durum Desf.) under Mediterranean condition
Keywords: Durum wheat, drought, tolerance index, stress tolerance index, stress intensity.
AbstractDrought is a wide-spread problem seriously influencing durum wheat (Triticum durum Desf.) production and quality, 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 varying environmental conditions. Ten
durum wheat cultivars were evaluated under both moisture stress and non-stress field environments using a randomized complete
block design for each of the environment. Six drought tolerance indices including stress susceptibility index (SSI), stress tolerance
index (STI), yield stability index (YSI), mean productivity (MP), harmonic mean (HMP) and geometric mean productivity (GMP)
were used. The indices were adjusted based on grain yield under drought and normal conditions. Yields in the normal condition
were not correlated with yields in the stress condition, better stress susceptibility index (SSI) was associated with low yield under
normal conditions, and therefore this index could not identify cultivars with good performance in both stress and non-stress
condition. The significant and positive correlation of GYp and MP, GMP and STI showed that these indices were more effective
in identifying high yielding cultivars under different moisture conditions. Stress tolerance index (STI) gave identical cultivar
classification with the geometric mean (GMP), both being better than SSI in identifying top yielders in contrasting water
availability conditions. The results of calculated gain from indirect selection from moisture stress environment would improve
yield in moisture stress environment than selection from non moisture stress environment. Wheat breeders should, therefore, take
into account the stress severity of the environment in choosing an index.
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