Effects of Organic Acids on Modulation of Bicarbonate Stress in Some Peach Cultivars grafted on GF677 Rootstock

Bicarbonate stress causes Fe chlorosis which, in turn, results in yield reduction, the delay in fruit bearing and reduced fruit quality, photosynthesis and growth processes in plants. In this study, the effects of organic acids on the alleviation of bicarbonate stress in some peach cultivars was investigated. The experiment was conducted as a factorial experiment based on a randomized complete block design with 18 treatments and three replications. Factors studied in this experiment included three peach cultivars grafted on GF 677 rootstock, three levels of calcium bicarbonate (0, 7.5 and 15 mM) and two levels of organic acid (0 and 10 mM). Among the studied cultivars, J.H. Hale cultivar was the most sensitive cultivar and Barzegar cultivar was the most resistant to chlorosis induced by iron deficiency. Organic acids significantly improved the growth characteristics of different cultivars, especially under calcium bicarbonate stress conditions. Organic acids reduced the intensity of chlorosis due to iron deficiency in the studied cultivars by up to 20%. In the study of physiological and biochemical traits, it was found that organic acids improve the relative water content of leaves (up to 16%), chlorophyll content (up to 33%), proline accumulation (up to 35.9%) and also increases the activity of antioxidant enzymes including catalase (up to 23.4%), superoxide dismutase (up to 26.5%) and guaiacol peroxidase (up to 14.4%). Organic acids improved the growth characteristics of peach seedlings under bicarbonate stress conditions by improving water relations, leaf chlorophyll and antioxidant enzymes.