Variation in Leaf Nutrient Concentrations of Freeman Maple Resulting from Canopy Position, Leaf Age, and Petiole Inclusion

Abstract

Consistent evaluation of nursery crop nutrient status within and among plots and years requires careful consideration of leaf collection practices. The objectives of this study were to determine the differences and variability among leaf age and cardinal position within the tree. Another objective was to determine if petioles should be included in leaf samples. Leaves were collected from seven trees of the Freeman maple (red–silver maple hybrid) Celebration® (Acer ×freemanii) from two leaf ages (early- and late-season leaves) and four positions (north, south, east, and west). On the south side of each tree, samples were separated into lamina, petiole, or lamina + petiole samples. Leaf traits were not different among positions, except that leaves on the north side of the tree had a lower specific leaf weight (SLW). Leaf nitrogen (N) was slightly lower on the north and west sides of the tree and leaf calcium (Ca) was highest on the south side of the tree, but otherwise position (i.e., side of the tree) had very little effect on leaf nutrient concentrations. Older leaves (leaves produced early in the season) were darker green and had a higher leaf area, longer petiole length, and lower SLW. Older leaves also had higher concentrations (on a mass basis) of all nutrients analyzed. Petiole concentrations of Ca, magnesium, and manganese were higher than lamina concentrations, whereas concentrations of N, sulfur, iron, zinc, boron, copper, and aluminum were all higher in the lamina. These differences, however, did not affect nutrient analyses conducted on samples consisting of lamina + petiole or lamina only. Variation within samples was lowest on the east and south sides for macro- and micronutrients, respectively, in late-season leaves. Based on the relative variation within samples, samples for nutrient analysis of red maple and red maple hybrids should consist of leaves collected from the southeast side of the tree and can consist of samples with or without petioles attached to the lamina.