Temperature response in wild oat (Avena fatua L.) generations segregating for seed dormancy

Crosses between parents with high and low levels of seed dormancy ill wild oat were used to produce F-1, F-2 and backcross populations. Germination phenotypes were determined by imbibing all populations at 15 and 20 degrees C. Rapid germination of genetically more dormant generations was favoured at the lower temperature, i.e. a generation by germination temperature interaction was observed. Evidence that dominance shifted from early germination at 15 degrees C to late germination at 20 degrees C is presented. Epistatic gene action may have been detected at 20 degrees C but not at 15 degrees C. Cumulative germination percentages of F-1 caryopses imbibed at 10, 15, 20 and 25 degrees C revealed an inverse relationship between germination rate and temperature. The narrow-sense family heritability of the seed dormancy phenotype of F-7 recombinant inbred lines pcr se was h(f,F=1)(2) = 0.75 with exact confidence limits of 0.64 and 0.83, Six factors were estimated to be segregating between the dormant and nondormant parents. Genotype by germination temperature interactions may play an adaptive role that allows wild oat to persist in diverse ecosystems.