Seasonal Soil Waterlogging Influences Water Relations and Leaf Nutrient Content of Bearing Apple Trees

Abstract

Abstract Bearing ‘Macspur’/M.26 apple trees (Malus domestica Borkh.) were grown in plastic-lined basins under orchard conditions. Four treatments were imposed in each of 3 years consisting of controls and 6-week periods of soil waterlogging in the spring, summer, or fall. Stomatal conductance (gs), transpiration rate (E), leaf water content (LWC), and stem water potential (ψstem) were measured at the end of each waterlogging period. Stomatal conductance was significantly reduced by spring and summer waterlogging, but not by fall waterlogging. Reduction in g, and E generally increased over years. Stem water potential after spring and fall waterlogging averaged 8% less negative than controls in all 3 years, with no trend over the 3 years. In contrast, of summer-waterlogged trees was unaffected, 45% was more negative, and 31% less negative than controls in the first, second, and third year of treatment, respectively. Annual reductions in growth and yield due to the waterlogging treatments were related to decreased gs and to both negative and postive changes in ψstem. Leaf levels of N, P, K, and Cu measured in July were reduced only by summer waterlogging, with no trend in reponse over years.