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

Abstract

The aim of the current study was to assess the effectiveness of NH<sub>4+</sub> 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 NH<sub>4</sub>NO<sub>3</sub> and with 50 and 100 mmol of (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub> 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 (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub>, 12 hrs) were 82±3.7% and 80±4.47 %, respectively, followed by T1 and T3 (50 mmol (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub>, 12 h and 100 mmol NH<sub>4</sub>NO<sub>3</sub>, 12 h). When compared to the unprimed tomato seeds, the NH<sub>4+</sub> priming with NH<sub>4</sub>NO<sub>3</sub> and (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub> 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 NH<sub>4+</sub> 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 NH<sub>4</sub>NO<sub>3</sub> and (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub> as NH<sub>4+</sub> priming in tomato plants because other factors and nutrition can play a role in seed germination and plant growth development.