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Selection for Postflowering Drought Resistance in Short- and Medium- duration Cowpeas Using Stress Tolerance Indices

Nouhoun Belko, Ndiaga Cisse,* Ndeye N. Diop, Gerard Zombre,
Samba Thiaw, Satoru Muranaka, and Jeffrey. D. Ehlers

Abstract Available drought-tolerant cowpeas [Vigna
unguiculata (L.) Walp.] are few, and identification
of additional genotypes with even greater
tolerance to drought would enable breeders to
develop cultivars with higher and more stable
yields across the semiarid ecologies where this
crop is grown. The objectives of this work were
to evaluate the effects of drought on the growth
and reproduction of a diverse set of cowpea
germplasm and select drought-tolerant and
high-yielding genotypes using stress tolerance
indices. Thirty short- and 30 medium-duration
genotypes were separately assessed in adjacent
drought-stressed (DS) and nonstressed
(NS) environments in a randomized complete
block design with three replications. Selection
indices, including stress tolerance index (STI)
and geometric mean productivity (GMP), were
estimated considering grain yield under NS and
DS environments and the stress intensity. Overall,
the medium-duration genotypes had higher
yields than the short-duration ones under both
DS and NS conditions. On average, fodder and
grain yields were 40 and 65% less under DS conditions
and maturity occurred 4 d earlier. IT85F-
3139, IT93K-693-2, IT97K-499-39, IT93K-503-1,
IT96D-610, IT97K-207-15, KVx-61-1, KVx-403,
KVx-421-25, and Mouride had the highest grain
yields under both DS and NS environments and
were identified as the most drought-tolerant and
high-yielding genotypes based on their rank in
terms of STI and GMP values. Therefore, these
cultivars may be valuable parents for breeding
programs whose objectives include developing
drought-tolerant cowpea cultivars.

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