ASHS 2024 Conference

Instances of water scarcity attributed to insufficient precipitation have amplified across the western United States (U.S.), leading to restrictions on ornamental plant irrigation. Fagopyrum esculentum (buckwheat) is widely used in pollinator-friendly U.S gardens due to its ornamental value and significance to pollinators. However, buckwheat's drought tolerance has not been widely investigated. The objectives of this research are to determine the effects of substrate volumetric water content on the visual quality, growth, and physiology of F. esculentum (common buckwheat), F. esculentum ‘Rose Red Soba’ and F. esculentum ‘Takane Ruby’. Cultivars were grown in an electromagnetic sensor-based automated irrigation system at substrate volumetric water content of 0.10 m3·m-3 (drought) and 0.40 m3·m-3 (control) for 35 days in a greenhouse. Plant growth index [(height (width 1 width 2)/2)/2], proportion of visibly wilted leaves, and the number of flowers were recorded weekly throughout the experiment. Gas exchange parameters were recorded at the termination of the experiment. Decreased substrate volumetric water content increased the number of visibly wilted leaves on three buckwheat cultivars. The plant growth index and number of flowers also declined as substrate volumetric water contents decreased from 0.40 to 0.10 m3·m-3. Alternatively, 'Rose Red Soba' and common Buckwheat exhibited a lower net photosynthesis rate in decreased substrate volumetric water content. Drought treatment also led to decreased stomatal conductance among all three buckwheat cultivars. Our results indicate that drought could impair buckwheat's ornamental value and growth due to the increased accumulation of visibly wilted leaves and decreases in plant growth index. Additionally, buckwheat's ability to attract pollinators could decline under drought conditions due to the loss of flower abundance. Nevertheless, 'Takane Ruby' buckwheat could maintain a higher capability of drought tolerance compared with 'Rose Red Soba' and common Buckwheat due to its capacity to maintain photosynthesis rate when substrate volumetric water content decreases.