Improvement of Medicago sativa seed tolerance to salt stress by Na2SiO3 and KNO3 treatments at different time levels

Opposition to destructive and side effects of salt stress, have limited suitable water and soil sources for plant culturing, is possible by increasing the tolerance level of seeds and seedlings. In present research, the effect of priming technique was studied with Na2SiO3 or KNO3 in 3, 6, 9 and 12 hours on Medicago sativa cv. Hamadani in response to 200 mM salt stress. Salinity caused a decrease of most of germination and growth indices from seeds and seedlings, whereas 3h-Na2SiO3 priming increased final germination percentage (FGP) and (3/6/9h)-KNO3 increased FGP, coefficient velocity of germination (CVG), compared to control. An improvement in mean germination rate (MGR) and mean germination time (MGT) was shown by 6h-Na2SiO3 and all KNO3 treatment times and increase of Vigor index (I) was observed at 3h-KNO3. Pretreatment with (3/6/9h)-Na2SiO3 and all h-KNO3 decreased T50 at stress and in non stress conditions, 9h-Na2SiO3 and 9h-KNO3 caused a decrease in mean daily germination (MDG) and an increase in Timson index and improvement of coefficient uniformity of germination (CUG). 12 hour treatments from both substances exacerbated the conditions and decreased the FGP, Vig (I) and (II) and decreased CVG. All-Na2SiO3 and (9/12)-KNO3 decreased the dry weight of shoots at stress. Proline was raised only with KNO3 and salt affected pigments negatively and priming increased them. In conclusion, priming elevated tolerance to salt stress and treatment compositions with the lower times were more efficient.