Submitted to: Texas Pecan Growers Association
Publication Type: Proceedings
Publication Acceptance Date: June 23, 2003
Publication Date: November 1, 2003
Citation: Grauke, L.J., Storey, J.B., Thompson, T.E., Wood, B.W. 2003. Leaf structure and nutrient content varies in native pecan populations. Proceedings of Texas Pecan Growers Association. 70:59-60. Technical Abstract: Seed was collected from 4-5 trees growing in each of 19 native populations distributed from Illinois to Oaxaca, Mexico. Seedlings were planted in a replicated test (USDA ARS Pecan Provenance Orchard, Byron, Georgia) with 11 blocks, with each of the 94 original trees represented by on open-pollinated seedlings in each block, and 967 total trees (due to imbalance). Leaf samples were collected from each tree in 1998 and 2002 for mineral analysis. In 2002, the fresh weight, leaflet area and dry weight of leaf samples was determined, permitting calculation of nutrient content on the basis of leaf area as well as nutrient concentration by dry weight. Leaflet area varied by population of origin, with the largest leaflets coming from seedlings originating from the northern and eastern range (Tennessee, Kentucky, Illinois, Mississippi, Missouri, Kansas, and northeastern Texas) and the smallest leaflets from seedlings in the western and southern range (west Texas through Mexico). Leaflet density (g dry mass/cm2) also varied by population of origin, and was negatively related to leaflet area. Seedlings originating from western Texas and Mexico had the greatest leaflet density. Concentration of leaf minerals varied by year, due in part to analysis by different labs. However, leaf concentrations of N, K, Ca, Mg, and Zn differed significantly by population. The highest concentrations of leaf Zn were found in seedlings originating from west Texas populations, and were distinguishable in Zn concentration from seedlings originating from an east Texas population. Tree size, measured as trunk diameter, varied significantly by population of origin, with the largest trees originating from particular populations in Mexico and Texas. This research has implications for the improved selection of regionally adapted rootstocks.