Development in Cowpea (Vigna unguiculata). I. The Influence of Temperature on Seed Germination and Seedling Emergence

Abstract

SUMMARYThe base (Tb), optimum (To) and ceiling (Tce) temperature for 50% seed germination and seedling emergence, and the thermal time at sub-optimal temperatures (θ1), were examined in experiments with a range of cowpea genotypes from different habitats and latitudes. There was substantial genotypic variation in seed germination for Tband To, but not for Tce. There was no evidence that genotypes from semi-arid habitats had higher values of Toor Tce, but estimates of Tbfor seed germination were related to latitude and were highest in genotypes originating from close to the equator. The significance of these responses as a component of developmental plasticity in relation to the adaptation of cowpeas is discussed.