Exogenously applied proline at different growth stages enhances growth of two maize cultivars grown under water deficit conditions

Exogenous application of potential osmoprotectants such as proline is an important shotgun approach to alleviate adverse effects of abiotic stresses on plants. However, information about the effects of exogenously applied proline in counteracting the adverse effects of water stress on crops is scanty. An experiment was therefore conducted to assess the ameliorative effect of exogenously applied proline on growth and photosynthetic capacity of two maize cultivars grown under water deficit conditions. Four-week old plants of 2 maize cultivars, viz., EV-1098 and AGAITI 2002 were subjected to water stress by maintaining moisture content equivalent to 60% field capacity. Different concentrations of proline applied as a foliar spray at the seedling, vegetative and seedling+vegetative stages were: no spray, 0.1% Tween-20 solution, 30 and 60 mM proline in 0.1% Tween 20 solution. Water stress reduced growth and photosynthetic capacity of both maize cultivars. However, exogenous application of proline counteracted the adverse effects of water stress on growth of both maize cultivars. Although proline induced improvement in growth of water stressed maize plants was almost similar at all growth stages, application of 30 mM proline proved to be more effective in inducing water stress tolerance as compared to the other level. Photosynthetic rate of water stressed plants of both maize cultivars was also enhanced due to foliar applied proline which was positively associated with sub-stomatal CO2 (Cv) and stomatal conductance (gs) as well as photosynthetic pigments. Overall, foliar applied proline ameliorated the adverse effects of water stress on growth and photosynthetic capacity of two maize cultivars.