2.1 Study Area
Trees were sampled from a five-year old avocado orchard located on the USDA-ARS, Subtropical Horticulture
Research Station, Miami, FL, USA (25°38´N, 80°17´W). South Florida has a subtropical marine climate with
146 cm mean annual precipitation falling mostly between May and October. Mean daily maximum and
minimum temperature range is between 26° C and 17° C for Nov – Apr, and between 31° C and 24° C for May –
Oct. Elevation at the site is 4 m above sea level. Soil is classified as a Krome very gravely loam (Loamy-skeletal,
carbonatic, hyperthermic Lithic Udorthents). The soil has a depth of 5 to 25 cm above an oolitic limestone
bedrock and is well drained. The trees were planted by auguring holes into the bedrock, inserting the sapling, and
backfilling the hole with pulverized rock and mulch.