Astronium graveolens is a native tree species from Atlantic Forest considered sensitive to O₃. This study aimed to determine which environmental factors, including air quality and meteorological conditions, have the most significant influence on gas exchange and the appearance of visible foliar symptoms in this species. Saplings were potted and exposed in a standardized manner in an open area in the southeastern city of São Paulo, Brazil. Gas exchange was measured weekly in the morning (9 am to 10 am), midday (11 am to 12 pm), and afternoon (2 pm to 3 pm) during the spring and summer seasons (n = 10). Data on O₃ concentration and meteorological conditions were obtained on-site. Principal component analysis identified that the morning hours provide the most favorable meteorological conditions for gas exchange. High temperature and VPD reduced gas exchange in the midday and afternoon. Although the AOT40 was high, there were no visible foliar symptoms, which was an unexpected result. We propose that the meteorological conditions, mainly the VPD and temperature, caused stomatal closure, and consequently prevented the absorption of O₃; therefore, there was no association between O₃ and reduction of gas exchange, nor manifestation of foliar visible symptoms. We consider that more studies are necessary for the proper use of A. graveolens as an O₃ bioindicator species.

Astronium Graveolens是来自大西洋森林的本地树种，被认为对 O ₃敏感。本研究旨在确定哪些环境因素，包括空气质量和气象条件，对该物种的气体交换和可见叶面症状的出现具有最显着的影响。树苗在巴西东南部城市圣保罗的空地上以标准化的方式盆栽和暴露。在春季和夏季 ( n  = 10)期间，每周在上午（上午 9 点至上午 10 点）、中午（上午 11 点至下午 12 点）和下午（下午 2 点至下午 3 点）测量气体交换。O ₃数据现场获得浓度和气象条件。主成分分析表明，早晨时间为气体交换提供了最有利的气象条件。高温和 VPD 减少了中午和下午的气体交换。虽然 AOT40 很高，但没有明显的叶面症状，这是一个意想不到的结果。我们认为气象条件，主要是 VPD 和温度，导致气孔关闭，从而阻止了 O ₃的吸收；因此，O ₃与气体交换减少之间没有关联，也没有叶可见症状的表现。我们认为需要更多的研究来正确使用A.graveolens作为 O ₃ 生物指示剂种类。