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 °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°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.