Osmotic stress caused by water scarcity or high salinity severely impairs plant morphology, physiology, and metabolism. It disrupts photosynthesis, promotes accumulation of reactive oxygen species, and reduces growth and yield. These stresses represent one of the greatest threats to global agriculture. Potassium deficiency, meanwhile, is widespread in soils worldwide, further reducing plant resilience to drought and salinity. While individual studies have suggested that potassium can improve tolerance, results have been inconsistent, influenced by ecosystem type, soil properties, and crop physiology. Due to these challenges, comprehensive meta-analyses are required to clarify the global role of potassium in alleviating osmotic stress across plant species and stress conditions.
A research team from Nanjing Agricultural University and the Jiangsu Province and Chinese Academy of Sciences conducted a large-scale meta-analysis to evaluate potassium's role in mitigating osmotic stress. The study, published (DOI: 10.1093/hr/uhae318) on February 1, 2025 in Horticulture Research, pooled data from 77 studies worldwide. Results show that potassium application consistently promotes plant growth, photosynthesis, and antioxidant defenses under both drought and salinity stress. By comparing responses across plant families and photosynthetic types, the study reveals that C3 plants benefit more strongly from potassium supplementation than C4 plants.
The meta-analysis integrated 2,381 paired observations covering morphological, physiological, and biochemical traits. Overall, potassium application boosted plant total dry weight by 12–30% and enhanced photosynthesis and stomatal conductance. It also reduced markers of oxidative damage, such as malondialdehyde and hydrogen peroxide (H₂O₂), while stimulating antioxidant enzymes including catalase, superoxide dismutase (SOD), and peroxidase (POD). Importantly, potassium improved osmotic adjustment by raising leaf relative water content, maintaining turgor pressure, and increasing the K⁺/Na⁺ ratio, especially under drought. Distinct stress types revealed unique patterns: drought-stressed plants responded more strongly than salt-stressed ones, suggesting that salinity’s combined osmotic and ion-toxic effects are harder to counteract. Plant type also mattered—C3 species exhibited pronounced gains in growth and photosynthesis, while C4 plants showed more limited improvements, particularly under salt stress. Collectively, the results highlight potassium as a key nutrient that not only supports plant metabolism but also acts as a physiological shield against osmotic stress.
“Potassium is often overlooked compared to nitrogen or phosphorus, yet our analysis demonstrates its central role in plant survival under drought and salinity,” said Min Wang, corresponding author of the study. “By synthesizing evidence from thousands of observations, we confirmed that potassium improves photosynthesis, water balance, and antioxidant activity. Importantly, it offers greater benefits under drought than salt stress and is particularly vital for C3 crops such as wheat, soybean, and rice. These insights can guide more precise fertilizer management for sustainable agriculture.”
The findings underscore potassium's value in climate-smart agriculture. As droughts intensify and soil salinity expands worldwide, optimizing potassium use could safeguard crop productivity and enhance food security. Beyond improving yield, potassium fertilization contributes to plant stress tolerance by enhancing water use efficiency, balancing nutrient uptake, and reducing oxidative damage. These insights can inform fertilizer strategies tailored to crop types and stress conditions, particularly in regions facing water scarcity. Moreover, the results suggest that prioritizing potassium in integrated soil management can support both agricultural resilience and ecological restoration efforts under global climate change.
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References
DOI
10.1093/hr/uhae318
Original Source URL
https://doi.org/10.1093/hr/uhae318
Funding information
This work was financially supported by the National Key Research and Development Program of China (2023YFD1901101), the Fundamental Research Funds for the Central Universities (KYT2024001), and the National Natural Science Foundation of China (32072673).
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.