Salicylic acid effects on stomatal characteristics and some growth of calendula plants (Calendula officinalis L.) under salt stress

In order to investigate the effects of salicylic acid on some growth and stomatal characteristics of calendula plant, a factorial experiment was conducted based on completely randomized design with five replications in the research Greenhouse of Shahid Bahonar University of Kerman in 2013. Salt stress levels including 1, 3, 5, 7 and 9 mmhos/cm were applied to the soil and salicylic acid solutions with 0, 100 and 200 mg/lit concentration were sprayed on plants. Results showed that both salt stress and salicylic acid reduced length and width of stomata. Compared to the control conditions, highest level of salt stress reduced plant shoot and root dry matter and also relative water content to 51, 58 and 24 percent, respectively. However, application of salicylic acid improved all these characteristics at all applied levels of salt stress. Compared to the control conditions, application of 200 mg/lit solution of salicylic acid increased plant shoot and root dry matter (24 and 28%), respectively. Meanwhile, 100 mg/lit salicylic acid solution increased the relative water content (9%) compared to the control.