Seed treatment with tryptophan improves germination and emergence of pepper under salinity stress

In this research, enhancing salinity stress tolerance in pepper (Capsicum annuum L.) during seed germination by tryptophan applications was investigated. In order to improve germination and emergence under salinity stress, pepper seeds were treated with tryptophan at various concentrations (0, 1, 10, 100 and 1000 mu M), after which they were subjected to seed germination and seedling emergence tests at optimum (0 mM NaCl) and saline (150 mM NaCl) conditions. The results indicated that pre-sowing seed treatment with tryptophan could enhance germination and emergence performance of pepper seeds under salinity stress conditions. Comparing the concentrations tested, treating the seeds with tryptophan in the range of 1-100 mu M was highly effective giving the highest germination and emergence percentages. Additionally, tryptophan application also enhanced the activities of antioxidant enzymes while reducing tissue H2O2 and MDA concentrations. Therefore, tryptophan, which is the precursor of the broad spectrum antioxidant, melatonin, could be used effectively in enhancing seed germination and seedling emergence performance of pepper under salinity stress conditions