STEM-FLOW, THROUGHFALL, AND CANOPY INTERCEPTION OF RAINFALL BY CITRUSTREE CANOPIES

It is generally believed that the interception of rain by the citrus t ree canopy can substantially decrease the throughfall under the canopy as compared to that along the dripline or outside the canopy (inciden t rainfall). Therefore, the position of placement of soil-applied agri chemicals in relation to the tree canopy may be an important considera tion to minimize their leaching during rain events. In this study, the distributions of rainfall under the tree canopies of three citrus cul tivars, 'Marsh' grapefruit (Citrus paradisi Macf.), 'Hamlin' orange (C itrus sinensis L. Osbeck), and 'Temple' orange (Citrus hybrid), were e valuated at four directions (north, south, east, west), two positions (dripline and under the canopy), and stem flow. There was not a signif icant canopy effect on rainfall amounts from stem flow or dripline, co mpared with outside canopy, for any citrus cultivar or storm event. Ho wever, throughfall varied significantly among the four cardinal direct ions under the canopy of all three citrus cultivars and was highly rel ated to the wind direction. Among the three citrus cultivars evaluated in this study, throughfall, stem flow and canopy interception account ed for 89.5 % to 92.7 %, 0.5 % to 4.7 %, and 5.8 % to 9.3 % of the inc ident rainfall, respectively.