Evaluation of different salicylic acid levels on some growth characteristics of pot marigold (Calendula officinalis L.) under limited irrigation

Water deficit is amongst the crop growth limiting factors and oxidative stress as a secondary stress occurs as a result of drought and water deficit. In order to study the effect of different salicylic acid levels in reducing water deficit impact on some growth characteristics of pot marigold plant, a factorial experiment was conducted based on CRD with three replications in Research Greenhouse of Faculty of Agriculture, Ferdowsi University of Mashhad during 2010-11. Experimental factors were salicylic acid concentration (0, 100 and 200 mM) and water deficit (100, 50 and 25 percent of soil field capacity). Results showed that different salicylic acid levels had a significant effect on leaf area and number, fresh and dry weight of plant, the number of lateral branches and flower number per plant, chlorophyll index, quantum yield, seed dry weight and seed number per plant. Leaf area and leaf number, the number and length of lateral branches, fresh and dry weight of plant, dry weight of flowers per plant, chlorophyll index, stomatal conductance, quantum yield were significantly reduced by a reduction in irrigation water. The interaction effects showed that 100 Mm of SA significantly reduced the impact of deficit irrigation at 50% FC, so that leaf area, the number of flowers per plant, seed dry weight and seed number per plant were significantly increased. It seems that SA increases plant stress tolerance through antioxidant production under stress condition and to some extent improves plant growth and dry weight of pot marigold under the conditions of this experiment.