Genetic relationships among cold, salt and drought tolerance during seed germination in an interspecific cross of tomato

Seed of BC1 progeny of an interspecific cross between a slow germinating Lycopersicon esculentum breeding line (NC84173; maternal and recurrent parent) and a fast germinating L. pimpinellifolium accession (LA722) were evaluated for germination under cold stress, salt stress and drought stress, and in each treatment the most rapidly germinating seeds (first 2%) were selected. Selected individuals were grown to maturity and self-pollinated to produce BC1S1 progeny families. The selected BC1S1 progeny from each experiment were evaluated for germination rate in each of a nonstress (control), cold-, salt- and drought-stress treatment, and their performances were compared with those of a nonselected BC1S1 population in the same treatments. Results indicated that selection for rapid seed germination in each of the three stress treatments was effective and significantly improved progeny germination rate under all three stress conditions. The results support the suggestion that same genes might control the rate of seed germination under cold, salt and drought stress. Furthermore, selection in each of the three stress treatments resulted in improved progeny seed germination rate under nonstress conditions, suggesting that genetic mechanisms that facilitate rapid seed germination under stress conditions might also contribute to rapid germination under nonstress conditions. In practice, therefore, selection for rapid seed 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 nonstress conditions, it might be more efficient to make selections under stress conditions.