Germination and tolerance of cowpea (Vigna unguiculata) cultivars to water stress

The objective of this study was to evaluate the tolerance of cowpea cultivars to water stress, during seed germination and seedling establishment. For this, a completely randomized experimental design was used in a factorial scheme consisting of nine cultivars of cowpea (BRS Guariba, BRS Potengi, BRS Itaim, BRS 17 Gurgueia, BRS Arace, Paulistinha, Maratank Costela-de-Vaca and Canapu-Branco) and two levels of osmotic potential induced by PEG 6000 (0.0 MPa (control) and -0.4 MPa) in four replicates of 50 seeds. The variables analysed were germination, germination first count, root and shoot lengths, and dry matter accumulation of shoots and roots. The dissimilarity between the genotypes was also determined by Euclidean distance. Germination and initial development of cowpea cultivars are impaired by the reduction in the potential to -0.4 MPa. The cultivars BRS Guariba, BRS Arace, Paulistinha and Canapu-Branco are the most tolerant to water stress, while BRS Potengi, BRS Itaim, BRS 17 Gurgueia, BRS Maratand and Costela-de-Vaca are the most sensitive in the early development stage.