Salicylic Acid’s Role in Reducing the Impact of Salinity on Plant Calendula (Calendula officinalis L.)

Exogenously applied salicylic acid (SA) as a growth regulator has been increased owing to tolerance to different stresses for example salt stress. The experiment was shown to conclude the influence of SA application on vegetative and flower treats of Calendula officinalis L. grown under salt stress and greenhouse conditions. For this purpose, a split-plot design was led with four concentrations of SA (250, 500, and 750 ppm) addition the control under three levels of salinity water irrigation, tap water (EC1= 0.6 ds.m-1), mixture water (1:1, tap water: well water) (EC2= 2.3 ds.m-1), and well water (EC3= 4.1 ds.m-1) with three replications. The results displayed that salinity diminished the time flowering and leaf pigments values. The spray applications of SA resulted in growth parameters (plant height, no. of leaves, leaf area, shoot and root dry masses), and flowering parameters (no. of inflorescences, a diameter of inflorescences and dry inflorescences mass) of calendula plants under salt stress. The highest leaf pigments values were obtained from 250 ppm SA application under well water treatments. The gas exchange system was determined at the flowering stage. Well water with SA increased proline, Ca, Na, and Cl; but they reduced K and N under salinity stress. Plants treated with 250 ppm SA had the best vegetative and flowering growth parameters at well water. These results recommend that 250 ppm SA might be used as a phytohormone to improve calendula plants which they irrigated by well water.