Genotypic Variability in Drought Performance and Recovery in Cowpea under Controlled Environment |
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| Authors: | A O Anyia H Herzog |
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| Institution: | Authors' address: Dr A. O. Anyia and Prof. H. Herzog (corresponding author;e-mail:;present address: Environmental Technologies, Alberta Research Council, PO Bag 4000, Vegreville, Alberta, Canada T9C 1T4), Faculty of Agriculture and Horticulture, Institute of Crop Sciences, Humboldt University Berlin, Albrecht-Thaer-Weg 5, 14195, Berlin, Germany |
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| Abstract: | Mid‐season drought is a factor frequently limiting crop production in the moist to dry savannah zones of the tropical and subtropical regions of the world. Ten cowpea genotypes were subjected to a cycle of drought at flowering followed by re‐watering to study variation in drought performance and recovery. Drought caused a reduction in leaf assimilation rate, transpiration rate and stomatal conductance with genotypic variances of 75.4, 57.9, and 83.3 %, respectively. Only genotypic variance in stomatal conductance increased appreciably under drought. Reductions in leaf water potential as a consequence of drought positively correlated with a decline in assimilation rate, which was associated with stomatal closure. One week after re‐watering, the three gas exchange parameters of stressed plants recovered fully and attained values 10–30 % higher than the well‐watered plants with increased genotypic variability. Reductions in the total dry matter during the drought interval varied from 11 to 50 % among genotypes, but were of minor importance for the total dry matter at maturity. After stress, the gain in dry matter varied considerably among the stressed genotypes, with stressed plants showing higher gain than the unstressed plants during this interval. This was associated with increased availability of assimilates due to enhanced green leaf area duration after stress release. Variability in drought recovery among genotypes was found, and appears to be more important for final yield than responses during drought. |
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| Keywords: | controlled environment cowpea drought recovery genotypic variance leaf water potential stomatal conductance |
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