The Influence of Temperature on Seed Germination Rate in Grain Legumes

Ellis, R. H., Simon, G. and Covell, S. 1987. The influence of temperature on seed germination rate in grain legumes. III. A comparison of five faba bean genotypes at constant temperatures using a new screening method.—J. exp. Bot. 38: 1033–1043. A screening procedure which requires information on the progress of germination at only four temperatures was able to define the response of the rate of seed germination to sub- and supra-optimal temperatures for whole seed populations of each of five faba bean (Vicia faba L.) genotypes. In one population of the cultivar Sutton the models for sub- and supra-optimal temperatures derived from the screen satisfactorily explained observations from an earlier separate investigation at a wider range of temperatures. Two discrete groups of genotypes were identified. Within each group the base temperature Tb did not differ significantly: for the landraces Lebanese Local Large and Syrian Local Large the value was estimated to be −7·5°C and for the landrace Lebanese Local Small and the cultivars Sutton and Aquadulce it was −4·0°C. The optimum temperature for the 50th percentile [To(50), at which temperature the rate of germination is maximal] also varied between these two groups of genotypes, being 20·5–21·5°C for the first group and 24·5–26·0°C for the second. In several temperature regimes some of the viable seeds within a seed population failed to germinate. Nevertheless, even at temperatures where a substantial proportion of the seeds failed to germinate the models defined by the screening method predicted the germination times of those seeds which did germinate.