Exogenous silicon improves salt tolerance of Fenugreek (Trigonella foenum-graecum L.) during seed germination and early seedling stages

In the present study, we investigated the effects of exogenous silicon (Si) treatment on seed germination, embryo viability, seedling growth, antioxidant molecules and osmotic regulation in fenugreek under salt stress. The seeds were germinated in Petri dishes at 25 ± 1 °C for 8 days under 0 mM (control) versus 200 mM NaCl (salt stress) with or without 3 mM Si treatment. The obtained results showed that salt stress significantly reduced final germination percentage, germination speed, velocity index, germination energy, peak value, germination value and vitality index, but increased the mean germination time of fenugreek seeds. Salinity also significantly impaired seedling length and fresh weight. However, Si supplementation contracted the negative impacts of salinity and significantly increased all of the studied germination traits except of mean germination time. Additionally, Si alleviated the negative effects of salt on embryo viability and improved its ability to mobilize sugar and protein reserves. Furthermore, 200 mM NaCl increased Na+ content and induced the oxidative stress reflected by high malonyldialdehyde content, reactive oxygen species accumulation and electrolyte leakage percentage. However, salt-mediated oxidative stress was alleviated by Si treatment through a significant decrease of Na+ content and an increase of endogenous Si content, which correlated with a significant induction of enzymatic and non-enzymatic molecules with antioxidant function. Altogether, these findings suggested that, the exogenous Si treatment could be a potential method to enhance salt tolerance of fenugreek during seed germination.