Water uptake dynamics for adult peach trees in a subtropical humid climate

Abstract

Low-chill peach [Prunus persica (L.) Batsch] 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, irrigation is required to ensure fruit production in peaches. Available irrigation recommendations and peach crop coefficients (Kc) were determined in Mediterranean and temperate climates, and they can overestimate water demand in humid subtropical climates. Thus, a two-year study was conducted in Citra, FL, aiming to determine the water requirements and Kc values for four-year-old peach trees in humid subtropical conditions. A daily soil water balance and the crop evapotranspiration (ETc) was determined using soil volumetric water content recorded every 10 min. Five soil probes, each equipped with soil moisture sensors at 10, 20, 40, and 80 cm of soil depth representing soil depth layers of 0–15, 15–30, 30–60, and 60–90 cm, respectively placed under the tree canopy. The ratios of daily ETc and Penman-Monteith FAO-56 reference evapotranspiration were used to estimate Kc for phenological stages of adult (≥4-year-old) peach trees. A soil water depletion coefficient (Ks) was estimated obtaining a threshold of 25.8 % available soil water depletion before trees undergo water stress. Daily ETc ranged from 0.22 mm d−1 during dormancy to 3.65 mm d−1 during shoot development. Values of Kc for peach trees ranged from 0.30 during dormancy to 0.69 during fruit maturity. The use of peach tree Kc adapted for subtropical humid conditions reduce the estimated crop water requirements by 21 % compared to the Kc values reported in FAO-56 guidelines.