Germination and initial growth of common bean plants under water deficit as affected by seed treatment with S-nitrosoglutathione and calcium chloride

Abstract

New practices to improve the germination and the initial establishment of seedlings are needed to improve crop development in rainfed areas, where drought events may happen just after sowing. Here, we tested the hypothesis that pre-treatment of common bean seeds with S-nitrosoglutathione (GSNO)—a nitric oxide donor (NO)—or calcium (Ca2+) improves the germination and initial seedling growth under water deficit and both, together, will act synergistically. Firstly, common bean seeds were soaked in GSNO solutions at 50, 100, 500, 1000 and 2000 µM and calcium chloride (CaCl2) at 1, 5 and 10 mM. Then, seeds were subjected to well-watered and water deficit conditions. In another assay, seeds were treated as described above and then the seedlings were transferred to nutrient solution and subjected to water deficit imposed by polyethylene glycol (– 0.3 MPa). In general, our data indicated that pre-treatment of common bean seeds with GSNO or Ca2+ improved germination and root growth under water deficit in a dose-dependent manner. Further tests with a NO scavenger (cPTIO), a Ca2+ chelator (EGTA) and reduced glutathione confirmed the roles of both GSNO and Ca2+ in improving seed germination. However, such improvement in early development of seeds pre-treated with GSNO or Ca2+ was short and no differences among treatments were found at the end of the experimental period. Additionally, seed pre-treatment combining GSNO and Ca2+ aggravated the effects of water deficit on germination and initial development of common bean seedlings, indicating that GSNO nulled any positive effect of Ca2+ and vice versa.