The Physiological and Photosynthetic Responses of Plane Trees (Platanus orientalis L.) to Trunk Injection with Iron Compounds and Seaweed Extract (Ascophyllum nodosum) Under Summer Stressful Conditions in Isfahan

Leaf chlorosis and early leaf loss disturb the growth of plane trees in the urban landscape of Iranian cities. The present experiment was conducted to study the effect of trunk injection using the low-pressure Fertinyect endotherapy system with iron sources and seaweed extract for reducing leaf chlorosis of plane trees compared to soil application of iron sequestrone in the randomized complete block design with 3 replications. The experimental treatments included the injection of iron amino chelate, iron gluconate, iron citrate, and iron sulfate in combination with seaweed extract compared to the soil application of iron sequestrone and the control. Chlorophyll content, leaf iron, Fv/Fm ratio, leaf relative water content, stomatal carbon dioxide, photosynthesis, transpiration rate, water use efficiency and tree visual quality were evaluated. The iron amino chelate 4% + seaweed extract 2% and iron gluconate 4% + seaweed extract 2% compared to other treatments led to the most significant increase in leaf chlorophyll, iron content, leaf relative water content, Fv/Fm ratio, tree visual quality, and the improvement of the photosynthetic parameters. In general, trunk injection with iron in combination with seaweed extract was beneficial due to the effect of iron on chlorophyll synthesis, and growth stimulation by seaweed extract.