Determination of salt tolerance threshold of different fenugreek (Trigonella Foenum-graecum L.) ecotypes at germination stage using experimental models

This research was conducted to investigate effects of salinity on seed germination and evaluate experimental models for determination of salt tolerance threshold under laboratory conditions. Seeds of five fenugreek ecotypes (hendi, Ardestani, Isfahani, Neyrizi, Mashhadi) were placed in petri dishes and after adding of water (control, 3, 6, 9, 12, 15, 18, 21, 24, 27dS/m) were transferred in a germinator. The statistical design was completely randomized as factorial experiment with three replications. Results showed that increasing salinity upto 6dS/m had no effect on germination, however, higher salinities, the germination was decreased. Salinity at 24 and 27 dS/m reduced seed germination percentage by 29.8% and 80.81%, respectively. seed germination rate gradually decreased with increasing in salinity. This reduction was not significant for Ardestani and Neyrizi up to 3 dS/m and for Isfahani, Hendi and Mashhadi up to 6 dS/m. Results showed that low salinity levels increased seedling length, root length, shoot length and seed vigor index, whereas their high levels had an inhibitory effect. According to the linear model, the mean salt tolerance threshold of fenugreek was obtained 21.83 dS/m, with a reduction slope of 17.09%. Although Isfahani ecotype had a lower salt tolerance threshold (20.32 dS/m), it had the lowest reduction slope (10.37%), as well. Non-linear models also showed that the highest salinity in which seeds were germinated by 50% (25.81 dS/m), was obtained from Isfahani ecotype. Therefore, based on these results and the salt tolerance index, Isfahani ecotype can be introduced as the most tolerant one to salinity stress.