Alleviation Mechanism of Melatonin in Chickpea (Cicer arietinum L.) under the Salt Stress Conditions

Melatonin (MT) is considered to be a hormone involved in increasing tolerance in plants under stress. The effect of different doses (0, 50, and 100 mu M) of MT on the growth, biochemical and physiological properties of chickpea under salt stress was investigated. Salt stress significantly suppressed the growth, leaf relative water content (LRWC), chlorophyll reading value (CRV), chlorophyll a, chlorophyll b, and total chlorophyll. Salinity conditions also caused a decrease in macro- and micronutrients, while electrolyte leakage (EL), hydrogen peroxide (H2O2), malondialdehyde (MDA), and proline contents, catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) activities increased under salinity conditions. MT treatments increased plant fresh weight, plant dry weight, root fresh weight, root dry weight, plant height, stem diameter, LRWC, CRV, chlorophyll a, chlorophyll b, total chlorophyll, total carotene of chickpea seedlings under 75 and 150 mM NaCl compared to the non-MT treatment. Especially, 100 mu M MT treatment under 75 and 150 mM salinity conditions reduced the H2O2 and MDA contents compared to the non-MT-treated plants. Moreover, exogenous MT increased the K+/Na+ and Ca+2/Na+ ratios under salt stress conditions. It could be concluded exogenous MT treatments alleviated the salt stress on chickpea by modulating physiological and biochemical properties. Especially 100 mu M MT treatment can be suggested for decreasing the negative influence of salinity on chickpea seedlings.