2019 ASHS Annual Conference

Low-chill peach cultivars allow Florida growers to become competitive by offering fruits earlier than northern states for premium prices. Due to the predominance of sandy soils in Florida, intensive irrigation management is required for most of the season to avoid water stress. Available irrigation recommendations and peach crop coefficients (K_c) were determined in arid and Mediterranean climates and they can overestimate water demand in humid subtropicalclimates. A two-yearstudy was conducted in Citra, FL aiming to determine the water requirements and K_cvalues for adult peach trees in humid subtropical conditions. Five soil probes equipped with four capacitance soil moisture sensors each were placed under the tree canopy, soil volumetric water content was recorded every 10 min and used to determine the daily soil water balance and crop evapotranspiration (ET_c). The ratios of daily ET_cand Penman-Monteith reference evapotranspiration were used to estimate K_cfor phenological stages of adult (> 3yr old) peach trees. A water depletion coefficient was estimated and the threshold of 25.8% available soil water depletion before trees undergo water stress was determined. Daily ET_cranged from 0.22 mm·d^-1during dormancy to 3.65 mm·d^-1during shoot development. Daily K_c ranged from 0.30 during dormancy to 0.69 during fruit maturity. The values of K_c determined in this study provide a more accurate estimation of peach water requirements for humid subtropical climates compared to the K_cvalues determined for Mediterranean regions which tended to overestimate peach water demand under subtropical humid climate.