Mohamed, H. A., Clark, J. A. and Ong, C. K. 1988. Genotypic differences in the temperature responses of tropical crops. I. Germination characteristics of groundnut (Arachis hypogaea L.) and pearl millet (Pennisetum typhoides S. & H.).—J. exp. Bot. 39: 1121–1128. The germination at constant temperature of several genotypes of groundnut and pearl millet was investigated between 0°C and 50°C on a thermal gradient plate. Large differences in both germination rate and percentage germination were observed in both species. Base temperatures vary from 8–11.5°C and 8–13.5°C in groundnut and millet, respectively and optimum temperatures from about 29–36.5°C in both. Maximum temperatures for germination ranged from 41–47°C. The results are discussed in terms of adaptation to high soil temperature and crop establishment in the semi-arid tropics.