Abstract

CARDONA-AYALA, Carlos et al. Physiological and biochemical responses of the cowpea bean (Vigna unguiculata L. Walp.) under a water deficit. rev.colomb.cienc.hortic. [online]. 2014, vol.8, n.2, pp.250-261. ISSN 2011-2173.

The cowpea bean contributes to human and animal feed in many regions of the world, especially in places where droughts restrict agricultural production. The aim of this study was to identify some physiological and biochemical responses of this species under drought stress conditions in the reproductive phase. We used a completely randomized design with a 2x6 factorial arrangement (2 soil moisture levels and 6 genotypes) and three replicates. The grain yield/plant, number of pods/plant, number of seeds/pod and pod length were analyzed, and the relative yield reduction and drought susceptibility index were estimated. The gas exchange and activity of the catalase and ascorbate peroxidase enzymes, as well as the contents of chlorophyll, carotenoids, free protein, and proline, were analyzed. The drought stress caused a decrease in the grain yield/ plant of 57.72%, the number of pods/plant of 49.40% and the number of seeds/pod of 32.07%. At 17 days of drought, the photosynthesis began showing values near zero when the soil moisture content was reduced by about 40% of the field capacity, which could have been caused by stomatal limitations and possibly by biochemical limitations. The ratio of chlorophyll a/chlorophyll b (Chla/Chlb) was significantly lower and the malonaldehyde content was significantly higher in the plants under water stress.

Keywords : crop physiology; water stress; gas exchange; antioxidant enzymes; proline.

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