Improving salt tolerance threshold of Salicornia bigelovii at germination stage using gibberellic acid pretreatment at different levels of seawater salinity

This study was conducted in two separated experiments in the National Salinity Research Center in 2016. In the first experiment, the effect of 12 priming treatments consisted of potassium nitrate, sodium chloride, calcium chloride, and GA3 with control were investigated on seed germination of Salicornia (Salicornia bigelovii var. LVYUAN no.1) in order to select the best priming for the second experiment. In the second experiment, the effects of different salinity levels (12.5, 25.0, 37.5 and 50.0 dS m-1) and GA3 concentrations including 500 and 1000 mg L-1 were also evaluated on seed germination of the Salicornia genotype. The salinity treatments were prepared by different percentage of Persian Gulf water. The results showed that all the priming treatments increased germination percentage compared to the control, and the highest effect belonged to the concentrations of 500 and 1000 mg l-1 of GA3,by 142.3% and 119.1%, respectively. It was revealed in the second experiment that salt stress significantly reduced percentage and rate of seed germination, so that salinity treatments as 12.5, 25.0, 37.5 and 50.0 dS m-1 could reduce germination percentage by 11.8%, 40.3%, 63.3% and germination rate by 81.4% and 21.3%, 40.0%, 62.3% and 70.1%, respectively. However, GA3 priming could improve the salt tolerance and compensate a part of this loss, especially at 500 mg L-1. Application of GA3 increased salt tolerance threshold of Salicornia at germination stage. In no prim and GA3-priming treatments at 500 and 1000 mg L-1, salinity tolerance thresholds were 4.15, 9.31 and 6.56 dS m-1 and the threshold of 50% reduction was 20.36, 35.97 and 31.39 dS m-1, respectively. In general, the results indicated that seed germination and rate of Salicornia were improved using GA3.