Growth response of grafted and ungrafted citrus trees to saline irrigation

As population and agricultural pressure on high quality fresh water resources increases, it becomes more important to identify rootstocks and production techniques that allow the usage of lower quality water in irrigated agriculture. Water of 0, 1, 3, 5 and 10 dS m(-1) salinity was applied to grafted (with Olinda Valencia (Citrus sinensis var. Olinda) scion) and ungrafted sour orange (Citrus aurantium L.), C22, and C146 (Citrus sunki Hort. Ex Tan. Chi Poncirus trifoliata L. Raf. 'Swingle') trees to evaluate the effect of grafting and rootstock variety on salinity tolerance. Grafted rootstocks had a lower survival rate at higher salinity concentration than ungrafted trees and effects were dependent upon tree variety. Height growth rate and standing leaf area of grafted citrus trees declined with increased salinity concentrations while the response of ungrafted and grafted citrus trees was variety dependent. Mortality increased and standing leaf area decreased with increasing tissue Na+ and Cl- concentrations. Mortality in response to salinity was greater in grafted rootstocks than mortality of ungrafted trees. Overall, C22 and C146 rootstocks and ungrafted trees were found to be more tolerant of saline conditions than grafted SO rootstock or ungrafted SO trees. (C) 2014 Elsevier B.V. All rights reserved.