The Response of Pot Marigold Plant (Calendula officinalis L.) to Ascorbic Acid and Brassinosteroid under Drought Stress

To evaluate water deficit stress, brassinosteroid and ascorbic acid effects on photosynthetic pigments and some pot marigold’s compatible solutes, an experiment was conducted at the experimental field and labratory of university of Mohaghegh Ardabili in 2014. A factorial split experiment based on completely randomized design with three replications were used. Water deficit was induced by two levels of water stress (50 and 100 mm evaporation from class A pan) considered as main factor and brassinosteroid (0, 10-8 and 10-7 M) and ascorbic acid (0 and 10 mM) as sub factors. Results showed that water deficit, brassinosteroid and ascorbic acid increased soluble sugars, carotenoids and polyphenol oxidase activity. Water deficit decreased the rate of a, b and total chlorophylls, lysine and methionine. However, application of brassinosteroid and ascorbic acid decreased water deficit effects and increased the rate of a, b and total chlorophylls. Ascorbic acid application under stress condition increased the rate of lysine and methionine. Considering these results it can concluded that ascorbic acid and brassinosteroid increase marigold tolerance to water shortage by enhancing defensive system and prevention of photosynthetic pigments destruction. It seems application of brassinosteroid can improve medicinal particularity of marigold.