Effect of exogenous ammonium gluconate on growth, ion flux and antioxidant enzymes of maize (Zea Mays L.) seedlings under NaCl stress.

Ammonium gluconate (AG) provides both an organic carbon source and a nitrogen source, which can positively improve soil fertility and delay soil degradation. We investigated the underlying mechanisms of both NH₄⁺ - and C₆ H₁₁ O₇^- -mediated resistance to high salt concentrations in maize (Zea mays L.), and how they relate to antioxidant cellular machinery, root system architecture, root activity and lignin content in roots. Seedlings treated with AG maintained lower Na⁺ content, higher chlorophyll content, higher CAT and POD activity, compared with those without AG and ammonium carbonate (AC). The total size of the root system, primary root length and number of lateral roots detected on the primary root treated with AG decreased compared with those not treated with AG at the same NaCl concentration. However, average root diameter and root activity when treated with AG were significantly higher than roots without AG at the same NaCl concentration. Furthermore, total size of the root system, primary root length and number of lateral roots detected on primary rootsof seedlings treated with AG were higher than those treated with AC at the same NaCl concentration. These results suggested that AG may be a good organic fertiliser under salt stress by decreasing Na⁺ content and increasing chlorophyll content, activity of antioxidant enzymes, root diameter and root activity in maize seedlings.