Unlike most horticultural crops, blueberry (Vaccinium spp. section cyanococcus) prefers low-pH (4.2–5.5) soils. Other plants can acidify their rhizosphere to create a hospitable microenvironment. Southern highbush blueberry (SHB; Vaccinium corymbosum interspecific hybrids) plants do not acidify their rhizosphere in response to Fe deficiency, but other factors that affect rhizosphere pH have not been elucidated. We report results from two hydroponic experiments exploring N uptake effects on the rhizosphere pH of ‘Emerald’ SHB. Ammonium (NH4+) uptake led to rhizosphere acidification, whereas nitrate (NO3–) uptake led to rhizosphere alkalization. When grown in a split-root hydroponic system, roots that took up NH4+ acidified the rhizosphere to a greater extent that roots not exposed to NH4+. Rhizosphere acidification was observed even in a nontreated control. These results suggest that NH4+ uptake is the main driver of rhizosphere pH in SHB. N form effects suggest that fertilization with NO3– might lead to undesirable rhizosphere alkalization.
During the 2021 American Society for Horticultural Science annual conference, the Teaching Methods Professional Interest Group hosted the workshop “Going beyond Zoom: Tips and tricks for teaching horticulture online.” This workshop provided a forum for the dissemination of tools, materials, and approaches used to facilitate active learning in horticulture courses. Here we summarize the topics presented in the workshop as a resource for current and future horticulture instructors.