Effective selection criteria for assessing drought tolerance and yield under transient cycle of drought to re watering in rice
2015
Marcelo, V.A.C. | Orbase, M.A.R. | Chico, M.V. | Niones, J.M. | Sigari, T.A. | Desamero, N.V.
Drought is an important abiotic problem that seriously limits rice (Oryza sativa L.) production. The development of tolerant genotypes is hampered by the lack of effective selection criteria. This study aimed to evaluate the effectiveness of drought tolerant indices in identifying drought tolerant genotypes adapted to stress conditions. A total of 359 lines and check varieties were evaluated for yield under two cycles of drought stress at reproductive stage (E sub s) and non-stress (E sub ns) field condition at PhilRice-CES using x-lattice design with 3 replications. Ten drought tolerance indices viz, stress tolerance (TOL), mean productivity (MP), harmonic mean (HM), stress susceptibility index (SSI), geometric mean productivity (GMP), stress tolerance index (STI), yield index (YI), yield stability index (YSI) and modified STI (K sub, STI and K sub 2 STI) were used. The indices were adjusted based on grain yield under stress and non-stress conditions. Significantly high positive correlation of HM (r=0.995**), GMP (r=0.956**), STI (r=0.987**), YI (r=1.000**) and YSI (0.983**) to grain yield during drought, showed that these indices were more effective in identifying high yielding genotypes under E sub s conditions. Cluster and biplot analysis categorized superior lines under E sub s, based on yield performance under stress and the five selected indices. The calculated gain results from indirect selection from E sub s environment would improve yield under drought stress environment better than selection from non-stress environment. Breeding programs for drought should, therefore, take into account the stress severity of the environment in choosing an index.
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