Effects of site of origin, time of seed maturation, and seed age on germination behavior of Portulaca oleracea from the Old and New Worlds

The effects of site of origin, time of seed maturation, and seed age on germination behavior, in terms of final percentage of germination and time for 50% of final germination were investigated in the widespread weed Portulaca oleracea L. Seeds were collected in August from one population at each of three geographical regions of the Old and New Worlds representing temperate (Southern Ontario, Canada), Mediterranean (Tanta, Egypt), and subtropical (Al-Ain, United Arab Emirates (U.A.E.)) climates. The freshly harvested seeds were incubated in both light and dark at 15, 25, and 40°C. Seeds of the U.A.E. site showed little dormancy and germinated faster under a wider range of incubation conditions than did seeds from the Canadian site. To assess the effect of time of seed maturation on germination behavior, seeds were collected during the different seasons (November, February, May, and August) of the U.A.E. population. The percentage of germination was significantly higher for seeds collected in May and Novem...