Effect of Biological and Chemical Phosphorus on Yield and Some Physiological Responses of Pot Marigold (Calendula officinalis L.) Under Water Deficit Stress

To evaluate the physiological responses of pot marigold to water deficit under biological and chemical phosphorus sources, a factorial experiment was conducted based on randomized complete block design (RCBD) with three replications at Urmia University in 2014. Treatments were irrigation (at 50% and 80% Field Capacity; FC) and phosphorus (control, triple super phosphate, phosphate solubilizer bacteria and three arbuscular mycorrhizal fungi species included Glomus intraradices, G. mosseae and G. hoi). Analysis of variance showed the significant effect of irrigation on leaf chlorophyll-a, chlorophyll-b and total chlorophyll, also significant interaction effect of irrigation × phosphorus on carotenoid, leaf proline, total soluble sugars (TSS), flower and seed yield. Means comparison indicated the lowest concentration of leaf chlorophyll-a, chlorophyll-b and total chlorophyll in plants irrigated at 50% FC. The highest leaf proline (2.6 μmol/g Fresh Weight) belonged to plants fed by chemical phosphorus at 50% FC, and the lowest one (0.63 μmol/g fresh weight) was obtained from well-watered (irrigation at 80% FC) plants inoculated by G. mosseae. At all, the reduced photosynthetic pigments of chlorophyll (-a, -b and total), and increased concentration of osmolytes (proline and TSS) were achieved under water deficit stress. In mycorrhizal plants, seed yield was improved under water deficit condition. Also, the flower yield was enhanced by biofertilizers as well as chemical P. So, the results suggested replacing the chemical phosphorus with biological sources.