Vermicompost and Manure Compost Reduce Water-Deficit Stress in Pot Marigold (Calendula officinalis L. cv. Candyman Orange)

This study was carried out to evaluate the impact of irrigation regime and potting media on morpho-physiological and biochemical characteristics of pot marigold. The experiment was arranged factorially based on a completely randomized design. The first factor was irrigation regime in three levels of 80, 60 and 40% available water content and the second factor was potting media in five levels of 20% vermicompost, 30% vermicompost, 20% manure compost, 30% manure compost and control (sand and soil in equal proportions). Morpho-physiological traits (plant height, stem diameter, number of flowering stem, root diameter, root length, root dry weight, aerial dry weight, total dry weight, relative water content, ionic stability and water use efficiency) and biochemical traits (malondialdehyde content, catalase and peroxidase activity, chlorophyll and carotenoid contents) were measured. Morpho-physiological parameters, chlorophyll and carotenoid decreased under water deficit, while increased with application of vermicompost and manure compost. Also, lipid peroxidation, catalase and peroxidase activity enhanced under water deficit, while decreased with application of vermicompost and manure compost. In other words, the application of vermicompost and manure compost in potting media reduced the harmful effects of water deficit. Total dry mass and water use efficiency were about 3-fold higher in plants grown in 30% vermicompost or 30% manure compost substrate compared to those in control plants. The results suggest that the application of 30% manure compost could be recommended as suitable potting media due to reducing the negative effects of water shortages, helping to nourish the plant, cheapness and accessibility compared with 30% vermicompost.