Morphophysiological and Biochemical Responses of Zinnia elegans to Different Irrigation Regimes in Symbiosis with Glomus mosseae

Water deficit conditions, in addition to reduced water uptake, result in a reduction in nutrient uptake, and consequently, a substantial reduction in growth parameters, yield and quality. Substrate inoculation with arbuscular mycorrhizal fungi (AMF) as an environmentally friendly biofertilizer is an important strategy to improve the growth parameters and quality of products in such conditions. Therefore, an experiment was conducted on zinnia, under different irrigation regimes (40, 70 and 100% of field capacity; FC) and different substrate inoculation levels with Glomus mosseae (0, 2.5 and 5%), in order to examine their possible symbiosis and root colonization on morphophysiological and biochemical parameters in a factorial experiment based on a completely randomized design with three replications. The results showed the positive and significant effects of AMF on morphophysiological traits under all irrigation regimes compared to the control treatment (without AMF) such as flower longevity and antiradical properties. With increased drought stress, root:shoot ratio, flower diameter, flower longevity, water use efficiency (WUE), the chlorophyll content and nutrient uptake were significantly decreased, while the decreasing trends of these parameters were much lower in pots treated with AMF. The lowest cell membrane stability and highest free radicals were observed in 40% FC without AMF. The maximum antiradical and antioxidant properties occurred at the lowest irrigation level with the highest AMF inoculation level. The results indicated a significant increase in flower diameter and longevity, in 70% FC with 5% AMF inoculation treatment compared to the control. Compared with the control, WUE was significantly increased at a 5% AMF inoculation level.