Effect of foliar applied kinetin and indole acetic acid on maize plants grown under saline conditions

This study examined the effects of kinetin (KIN) and indoleacetic acid (IAA) sprayed on the leaves of salinity-stressed maize (Zea mays L. cv., DK 647 F1) plants grown in field conditions. Salt stress was created by adding 100 mM NaCl to the irrigation water through a drip irrigation system during the irrigation schedule. Kinetin (KIN), indole acetic acid (IAA), and their combinations were sprayed foliarly. Salt stress (S) reduced the total dry matter, grain yield, chlorophyll content, and relative water content (RWC), but increased electrolyte leakage and proline accumulation in the maize plants. Foliar applications of both KIN and IAA treatments overcame to variable extents the adverse effects of NaCl stress on the earlier mentioned physiological parameters. However, the combination of KIN plus IAA did not improve salinity tolerance in maize plants. Salt stress increased Na^+ concentration, and reduced those of Ca²⁺ and K^+ in the leaves of maize plants. Foliar application of both KIN and IAA significantly reduced Na^+ concentration and increased those of Ca²⁺ and K^+. Foliar application of KIN and IAA, especially at 2 mM, counteracted some of the salt induced adverse effects by enhancing essential inorganic nutrients as well as by maintaining membrane permeability.