Relationships between cold- and salt-tolerance during seed germination in tomato: Germplasm evaluation

Thirty tomato accessions representing six Lycopersicon species were evaluat ed for the rate of seed germination under no stress, cold-stress and salt-s tress conditions. Most accessions responded similarly to both cold-stress a nd salt-stress conditions (i.e. they were equally sensitive or tolerant to both stresses), however, a few accessions exhibited more sensitivity (or to lerance) to one stress than the other. In addition, some accessions that ge rminated relatively rapidly under non-stress conditions exhibited great sen sitivity to both cold stress and salt stress. Across accessions, significan t (P < 0.01) positive phenotypic correlations were observed between germina tion rate under control and cold stress (r(p) = 0.89), control and salt str ess (r(p) = 0.63) and cold stress and salt stress (r(p) = 0.77). The result s indicate that the rate of tomato seed germination under non-stress, cold- and salt-stress conditions may be controlled by the same genes (or physiol ogical mechanisms), but additional components may be involved which affect germination rare under specific stress conditions.