The efficacy of ammonium as seed priming agents for promoting tomato (Solanum lycopersicum L.) germination under salinity stress

The aim of the current study was to assess the effectiveness of NH4+ priming to enhance tomato seed germination and plant growth under saline stress. In the absence of light at 25 +/- 1 degrees C, tomato seeds were primed with 50 and 100 mmol of NH4NO3 and with 50 and 100 mmol of (NH4)2SO4 for 12 and 24 h, respectively. In the seed germination test, twenty primed seeds were used for each treatment, along with five replica plates and a control, and were all incubated at 25 degrees C with 25 mL of moistened water. In a second greenhouse experiment, primed seeds were planted in garden soil and watered with tap water, salt water, and a control. The concentration of saline water (50, 100, 150, and 200 mmol NaCl) was gradually raised after a 10-day break. The germination percentages in T5 (50 mmol (NH4)2SO4, 12 hrs) were 82 +/- 3.7% and 80 +/- 4.47%, respectively, followed by T1 and T3 (50 mmol (NH4)2SO4, 12 h and 100 mmol NH4NO3, 12 h). When compared to the unprimed tomato seeds, the NH4+ priming with NH4NO3 and (NH4)2SO4 improved plant height and other growth parameters. Furthermore, the chlorophyll and total flavonoid content were improved in both saline and non-saline treatments. In terms of salinity, the NH4+ priming increased the proline content while decreasing the total protein content. It is concluded that further research will be needed to clarify the effect of NH4NO3 and (NH4)2SO4 as NH4+ priming in tomato plants because other factors and nutrition can play a role in seed germination and plant growth development.