Modulation of growth parameters, proline content and mineral nutrients in maize (Zea mays L.) by exogenously applied glycinebetaine at different growth stages under salt stress

Effect of glycinebetaine (0, 50 and 100 mM) applied as a foliar spray at different growth stages i.e. vegetative, reproductive and both at the vegetative and reproductive stages on growth, proline accumulation and ion accumulation was investigated in plants of two maize cultivars under saline conditions. Salt stress caused a significant reduction in growth, leaves and roots K+ and Ca2+ while, Na+ and Cl- concentrations of both maize cultivars was significantly increased due to salt stress. Foliar applied glycinebetaine at the vegetative stage was more effective in ameliorating the adverse effects of salt stress than when applied at the reproductive or at both vegetative and reproductive stages. Foliar applied glycinebetaine did not change the leaf proline concentration in the salt stressed plants of both cultivars. However, exogenously applied glycinebetaine significantly reduced Na+ accumulation in the roots and leaves, while that of K+ increased, thereby resulting in higher K+/Na+ and Ca2+/Na+ ratios under saline conditions.