Effect of salicylic acid on some vegetative properties and biochemical changes of cucumber (Cucumis sativus L.) under copper stress

Soil and water toxicity with copper create serious problems on plant growth and production and human health. Therefore, in order to investigate the effect of salicylic acid (SA) on the morphological and physiological properties of cucumber under cupper (Cu) stress, an experiment was carried out as factorial based on completely randomized block design with three levels of cupper of 23, 47 and 94 µM and salicylic acid with two levels of 0 and 750 µM with three replications under hydroponics conditions. The results showed that copper stress negatively affected root dry weight, root volume, leaf area, leaf fresh and dry weight of cucumber plants. The greatest root fresh weight and Fv/Fm ratio was obtained with 23 µM cu treatment in both SA and non-SA treatments. Cu accumulated more heavily in roots than in shoots. The ascorbate peroxidase (APX) activity in the leaves was increased by increasing copper concentration and the highest activity of APX was observed in plants fed with 6 and was more pronounced in plants treated with SA, whereas, peroxidase (POX) activity showed reverse manner. The highest yield (530 g plant) was obtained in concentration of 23 µM Cu and treated with salicylic acid, but the lowest yield (282 g plant) was achieved in concentration of 94 µM Cu and without salicylic acid treatment. Based on these findings, the SA application appeared to alleviate the negative effects of Cu stress on the growth and biochemical of cucumber.