Relationships between cold- and salt-tolerance during seed germination in tomato: Analysis of response and correlated response to selection

Seeds of Fl progeny of a cross between a slow-germinating (UCT5) and a fast -germinating tomato line (PI120256) were evaluated for ger mination under n on-stress (control), cold-stress and salt-stress conditions, and in each tr eatment the most rapidly (first 5%) germinating seeds were selected, grown to maturity and self-pollinated to produce F-3 progeny. The selected F-3 pr ogeny from each experiment were evaluated for germination in each of the th ree treatments, and compared with germination rate of unselected F-3 progen y. Selection for rapid seed germination was effective under cold stress and salt stress, but not effective under non-stress conditions: Furthermore, s election in either cold-stress or salt-stress treatment significantly impro ved progeny germination rate under both cold-stress and salt-stress treatme nts, as well as the non-stress treatment. The results support the suggestio n that the same genes contribute to rapid seed germination under cold-, sal t- and non-stress conditions. In practice therefore, selection for rapid se ed germination under a single-stress environment may result in progeny with improved seed germination under a wide range of environmental conditions. Furthermore, to improve germination rate under non-stress conditions, it ma y be more effective to make selections under a stress treatment.