Improving salinity tolerance of germinating seeds by exogenous application of glycinebetaine in pepper

Glyciebetaine (GB) is an organic osmolyte that accumulates in a variety of different groups of plants in response to abiotic stress factors. In this study, the effects of pre-sowing seed treatment with GB on germination and emergence performance of pepper (Capsicum annuum L.) seeds under saline conditions were investigated. Seeds were immersed in 0, I, 5, 10 or 25 mM GB solutions for 24 hours after which they were dried for one day and subjected to germination and emergence tests at optimum and saline conditions. Exogenous GB treatment promoted pepper seed germination and emergence especially under saline conditions. The highest final germination and emergence percentage and rate were obtained from seeds treated with 10 mM GB whereas dry seeds and seeds treated with 0 mM GB exhibited the lowest germination and emergence performance. GB application also improved the synchrony of both germination and emergence under salt stress. Treating the seeds with 10 mM GB led to a significant decrease in MDA content and enhancement in proline content and SOD enzyme activity. The improvement in germination and emergence performance of pepper under salinity stress conditions following GB treatment may therefore be due to reduced lipid peroxidation and elevated SOD enzyme activity.