Table 3_Effects of uniconazole treatment on ‘Hass’ avocado productivity and gas-exchange parameters under Mediterranean climate.docx

Avocado (Persea americana Mill.) productivity faces major challenges due to rising market demand, climate variability, excessive vegetative growth, and labor-intensive management practices. This study evaluated the effects of soil-applied uniconazole (UNI), a gibberellin-biosynthesis inhibitor, on vegetative development, flowering, gas exchange, and fruit yield in mature ‘Hass’ avocado trees. The experiment, conducted over 2 years in a commercial orchard in northeastern Israel, compared three UNI concentrations (8, 12, and 16 mL tree-¹) applied via drip irrigation in May 2022 and May 2024. UNI treatments significantly reduced trunk diameter and increased floral bud density, indicating effective suppression of growth. Flowering intensity was enhanced during the first season across all UNI treatments, but not in the following year. Chlorophyll content showed a significant increase only in May 2023 for the 12 and 16 mL tree-¹ treatments. Physiological measurements revealed increased carbon assimilation and stomatal conductance in UNI-treated trees, particularly during the first season. Despite reductions in total yield at higher UNI doses in the first year of the experiment, the 12 and 16 mL tree-¹ treatments produced significantly larger fruit with improved size-class distribution, offering potential market advantages. Overall, the 8 mL tree-¹ treatment provided the best compromise between suppressing vegetative growth and enhancing carbon assimilation without compromising yield. These findings underscore the potential of UNI for optimizing canopy architecture and fruit quality in avocado orchards, particularly under a Mediterranean climate. Long-term assessments are recommended to refine dose strategies and evaluate commercial viability.

牛油果（Persea americana Mill.）的生产面临诸多严峻挑战，源于日益增长的市场需求、气候波动、过度营养生长以及劳动密集型的管理模式。本研究评估了土施烯效唑（uniconazole, UNI）——一种赤霉素生物合成抑制剂——对成熟‘哈斯（Hass）’牛油果植株营养生长、开花、气体交换及果实产量的影响。本试验于以色列东北部的商业果园开展，为期两年，分别于2022年5月与2024年5月通过滴灌施加三种浓度的UNI（8、12及16 mL·株⁻¹）。烯效唑处理显著降低了树干直径，同时提高了花芽密度，表明其可有效抑制植株营养生长。所有烯效唑处理组在试验第一年均提升了开花强度，但第二年未观察到该效果。仅在2023年5月，12和16 mL·株⁻¹浓度的处理组的叶绿素含量出现显著提升。生理指标测定结果显示，经烯效唑处理的植株的碳同化速率与气孔导度均有所提升，尤其在试验第一年表现显著。尽管试验第一年中高浓度烯效唑处理组的总产量有所下降，但12和16 mL·株⁻¹处理组的果实单果重显著提升，且果径分级分布得到优化，具备潜在的市场竞争优势。综合来看，8 mL·株⁻¹浓度的处理在抑制营养生长、提升碳同化速率与维持产量之间实现了最优平衡。本研究结果证实，烯效唑在优化牛油果果园冠层结构与果实品质方面具备应用潜力，尤其适配地中海气候条件。建议开展长期试验以优化施药剂量方案，并评估其商业应用可行性。