Water status and productivity of 'Hass' avocado trees in response to supplemental irrigation during winter

Abstract: The objective of this work was to evaluate the effects of supplemental irrigation, during winter dry season, on the water status and productivity of 'Hass' avocado (Persea Americana) trees. The experiment was carried out on a clayey Oxisol from 2014 to 2016, when extreme climatic events were recorded in the state of São Paulo, Brazil. The rainfed regime was compared with two irrigation regimes, applied during the whole and half of the irrigation run time defined by the grower, corresponding to 5,091 and 2,545 m3 ha-1 water, respectively. The following variables were evaluated: soil water tension; leaf water potential, color, and chlorophyll content; leaf and fruit abscission rates; tree size; and fruit size and yield. Supplemental irrigation applied during half of the run time increased fruit yield by 18.2%. However, irrigation applied during a fixed-time period and the occurrence of unusual rainfall spells caused soil water logging, negatively affecting tree growth and water status.

摘要：本研究旨在评估冬季旱季补充灌溉（supplemental irrigation）对哈斯鳄梨（Hass avocado，Persea Americana）树体水分状况与生产性能的影响。试验于2014—2016年在巴西圣保罗州的黏质氧化土（clayey Oxisol）上开展，该时期该州记录到极端气候事件。本试验设置雨养处理（rainfed regime）与两种灌溉制度：分别采用种植者设定的全灌溉时长与半灌溉时长，对应灌水量分别为5091 m³·ha⁻¹与2545 m³·ha⁻¹。本研究测定的指标包括：土壤水张力（soil water tension）、叶片水势、色泽与叶绿素含量、叶片与果实脱落率、树体大小以及果实大小与产量。结果显示，采用半灌溉时长的补充灌溉可使果实产量提升18.2%。然而，固定时段灌溉叠加异常降雨事件会引发土壤涝渍，对树体生长与水分状况产生负面影响。