Alleviative effects of Zinc on physiological properties and antioxidants activity of maize plants under salinity stress

Salinity is an important constraining factor in the way of crop production around the world. Plant nutrition management could alleviate the harmful effects of salinity. In order to evaluate the interaction effects of Zinc availability and different levels of salinity, an experiment was conducted using four levels of zinc(0, 10, 20 and 40 mg/kg) and three levels of NaCl salinity of irrigation water(0, 100 and 200 mM) on maize plants. Results implied that salinity affected total and shoot dry weight but they were improved by increasing Zn availability. Relative water content and proline accumulation were influenced by salinity and Zn interactions, but not with a particular trend. Furthermore, chlorophyll contents which destructively affected by salinity were improved by Zn application. According to the results, antioxidative activity (CAT, APX, SOD, POD and GR) increased by the combination of salinity and Zn to a great extent compared to sole salinity. Zn and salinity interactions also amplified the activity of mentioned antioxidants, but the difference between the Zn levels was not significant. Zn ameliorates sodium accumulation in plant tissues and the amount of sodium was reduced in different levels of Zn application. Moreover, decreased potassium content was observed on stressful plants which increased by Zn treatments. As a consequence, Zn concentration was bombed dramatically related to the applied Zn level, although salinity reduced the amount of absorbed Zn along the treatments. Generally speaking, Zn level of 20 mg/kg had the most alleviative properties on injurious effects of saline conditions in maize.