ASHS 2025 Conference

Selenicereus undatus (dragon fruit) is a high-value crop experiencing increasing global demand, yet limited research exists on how soil composition influences its growth and physiological performance. This study evaluated the effects of five distinct soil substrates on two dragon fruit varieties under controlled greenhouse conditions. 120 plants were arranged in a completely randomized design with five replications per treatment. The five soil treatments included Native South Texas Soil, 100% Sandy Soil, Sandy Soil 25% Sphagnum, Sandy Soil 50% Sphagnum, and 100% Sphagnum. Initial and final analyses of soil pH, salinity, texture, and nutrient content were conducted to monitor soil dynamics. Shoot length was measured at 0, 30, 60, and 90 days, while root biomass and architecture were assessed at harvest. Physiological traits, including chlorophyll concentration and total biomass, were also recorded at the conclusion of the experiment. Results revealed that soil composition influenced both above- and below-ground growth, with soils amended with sphagnum showing moderate increases in shoot elongation and chlorophyll content compared to unamended sandy and native soils. Root development varied across treatments, though no statistically significant differences in total biomass were detected. Variations in soil pH and organic matter content appeared to correlate with some physiological markers, suggesting a complex interaction between soil properties and plant response. While additional studies are needed to explore long-term productivity and fruit quality, these findings provide preliminary insights into how soil amendments may influence early-stage development of dragon fruit. This work contributes to ongoing efforts to optimize substrate management for dragon fruit cultivation, particularly in regions with poor native soils, such as South Texas.