Effect of Different Substrates and Nano Potassium Fertilizer on Morpho-Physiological Characteristics of Pot Marigold (Calendula officinalis L.) under Drought Stress

Aim of this study was the application of some organic materials in soil to improve pot marigold plant (Calendula officinalis L.) tolerance to drought stress. Experiment was performed as factorial based on a completely randomized design with three replications. Treatments were consisted of 100% of pot volume soil (control), 1 and 2 g kg-1 nano-potassioum fertilizer, 30% of pot volume cocopeat (v/v) + 70% soil, 30% of pot volume palmpeat + 70% soil and 30% of pot volume madder plant residues + 70% soil in three levels of drought stress (40, 60, and 80% of field capacity). According to the results, with increasing the drought stress, growth parameters were significantly decreased. The highest plant height (14.3 cm), leaf number (70.3), fresh and dry weight of shoot (79.2 and 11.1 g respectively) and roots (34.06 and 9.3 g respectively) were obtained in interaction of madder plant resideue and 60% field capacity drough stress treatment. In severe stress (40% field capacity), plants in medium with palm peat showed the lowest height (7 cm), leaf number (11.6) and crown diameter (10.1 cm). Generally, results showed that madder plant residues with compared to other treatments increased pot marigold resistance to drought stress. Regard to low cost, high moisture keeping and high porosity of madder plant residues, it could be as a suitable substance in arid land to reduce water consumption.