The Impact of Elevated Soil pH Levels on Cranberry Growth, Physiology, and Metabolites

pH plays a critical role in regulating nutrient availability and uptake, directly influencing plant growth and productivity. Cranberries grow optimally within a soil pH range of 4.2 to 5.5, but achieving this range remains challenging, even with amendments. This study evaluated the effects of elevated soil pH (7.0 to 7.2) on cranberry cultivation and identified factors contributing to adverse outcomes. Stems, leaves, and fruits were sampled from plants grown in soil with a pH ranging from 4.8 to 7.0. Nutrient composition, fruit size, yield, and anthocyanin content were analyzed. High soil pH levels resulted in significant reductions in fruit size (25-35%) and yield (29-56%). Cranberry plants grown in elevated pH conditions showed a significant (p < 0.001) decline in nitrogen, phosphorus, and potassium, and increased calcium and magnesium in soil, stems, leaves, and fruits. Additionally, photosynthesis and chlorophyll fluorescence were significantly reduced (p < 0.05 to 0.001). Certain amino acids, carbohydrates, and organic acids increased significantly (p < 0.05 to 0.0001) in high pH soils, suggesting a role in stress adaptation. Calcium levels in fruits and shoots were inversely correlated with fruit size and some metabolites. These findings demonstrate that soil pH levels above the optimal range (4.2-5.5) substantially impair cranberry growth and quality by disrupting nutrient balance and photosynthesis. The results highlight the urgent need for improved water and soil management strategies to mitigate high soil pH stress in commercial cranberry production.