Silver Nanoparticles (Ag NPs) Boost Mitigation Powers of Chenopodium Quinoa (Q6 Line) Grown under In Vitro Salt-Stressing Conditions

Abstract

Quinoa (Chenopodium quinoa) is of great economic importance and constitutes one of the model plants for salinity and drought tolerance in the Mediterranean climate. This study aimed to study the physiological responses of Q6 (a quinoa line developed by International Center for Bio-saline Agriculture (ICBA) in cooperation with the National Center for Agricultural Research (NARC), Jordan) grown under in vitro salt-stressing conditions (MS Media plus either 0, 25, 50, 75, 100, 150, or 200 mM of NaCl) and to determine the highest salt level that Q6 plantlets can tolerate. After this, different levels of chemically synthesized silver nanoparticles (Ag NPs) (25, 50, and 75 mg/L) were added to the growth MS media to examine if they can boost the mitigation powers of Q6 plantlets against the highest salt level that the Q6 plantlets could tolerate. Data showed that all tested growth parameters were negatively affected by adding NaCl to the media at all levels. Shoot length, proliferation, and fresh and dry weights declined to reach minimum values at 200 mM NaCl when compared to the other NaCl levels. Similarly, chlorophyll, protein, and ion content were negatively affected when exposed to NaCl at all levels, while proline increased significantly with increasing NaCl in the growth media. The addition of Ag NPs resulted in improving the mitigation powers of Q6 plantlets, especially when 75 mg/L Ag NPs were added, as this resulted in a significant improvement in microshoot growth under 200 mM NaCl when compared to the control. Adding 75 mg/L of Ag NPs to 200 mM NaCl improved shoot growth (3.56 cm) when compared to (1.04 cm) obtained plantlets that were grown in 200 mM NaCl alone. Further, other growth parameters were almost doubled by adding 75 mg/L of Ag NPs to 200 mM NaCl when compared to 200 mM NaCl alone. Additionally, adding Ag NPs (especially at the 75 mg/L level) to the media improved total chlorophyll, protein, and ion content while also reducing proline when compared to the control, which indicated an improvement in microshoot tolerance to salt-stressing conditions. These results indicate that adding specific concentrations of Ag NPs improves the growth performance and stress tolerance of Q6 grown under salt-stressing conditions.