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Water stress and water use efficiency in cowpea [Vigna unguiculata (L.) Walp.] under controlled environment Abdou Razakou I.B.Y1*, Addam Kiari S1, Mensah B2 and Akromah R2 1
Institut National de la Recherche Agronomique du Niger (INRAN), Niamey/Niger. Department of Crop and Soil Sciences/Faculty of Agriculture/KNUST/Kumasi/Ghana.
2
Accepted 1 May, 2013
Water use efficiency is one of the most important challenges for crop improvement programmes in the arid and semi-arid regions. An experiment was conducted from August to October 2011, in a plant house at Soil Research Institute, Kwadaso/Kumasi, in order to determine the effect of water stress on the vegetative stage of six cowpea varieties and assess agronomical mean for selecting water use efficient cowpea genotypes. A three replicated completely randomized design with two water treatments and six cowpea genotypes was used and data were collected on biomass (BM), water use (WU), water use efficiency (WUE), leaf senescence (LS) and root/shoot ratio (RSR). Highly significant effects of cowpea genotypes, water treatments and their interaction were observed on BM, WU, WUE and RSR. Water stress significantly decreased BM and WUE of water-stressed cowpea varieties compared to the control, and the largest reduction was observed in TN5-78 for BM (89%) and Nhyira for WUE (94%). The results also revealed that under water-stressed condition, varieties TN88-63 and Dan illa with relatively low WU, significantly recorded highest values of BM and WUE with 2.20 g and 4 g/kg, 1.78 g and 3g/kg respectively, while the largest percentage of 41.58% for RSR was recorded by variety TN5-78. BM showed a significant strong positive correlation (r = 0.96, p
