Evaluation of Physiological Changes in Flowering Dogwood under Drought Conditions in a Container Production System

Abstract

Flowering dogwoods (Cornus florida L.) are drought-sensitive ornamental trees. Two trials (in 2021 and 2022) were conducted to evaluate the physiological changes induced as a result of drought conditions. In an outdoor setting, trees were organized in a randomized complete block design. Three different irrigation treatments were applied at 125%, 25%, and 10% (control, moderate, and severe drought, respectively) of their daily water usage (evapotranspiration). The two physiological parameters normalized difference vegetation index (NDVI) and leaf moisture potential were collected every week for 1 month. Plant growth data (height and width) were collected at the beginning and the end of the study. Normalized difference vegetation index data collected with a handheld NDVI meter and a Sentera NDVI sensor mounted on an unmanned aerial vehicle (UAV) were correlated for ground truthing. In 2021, control plants had a greater plant width increase and shoot biomass, whereas no significant differences in growth were observed among the treatments in 2022. In both trials, the NDVI was the greatest for control plants compared with the other treatments on days 7, 14, 21, and 27. In both studies, no differences were observed for leaf moisture potential on day 7, but was greatest for controls on days 14, 21, and 27. The correlation between the handheld NDVI and the UAV NDVI was found to be strong and positive, ranging from 0.84 to 0.93 (trial 1: P ≤ 0.0001, P ≤ 0.0001, P = 0.0002, and P ≤ 0.0001; trial 2: P = 0.0002, P ≤ 0.0001, P ≤ 0.0001, and P ≤ 0.0001 for weeks 1–4, respectively). This information will be applicable to understanding the physiology of the crop and the inclusion of emerging technology in crop production and monitoring.