The effects and mechanism of climate change on vegetables quality: a review

Vegetables are an important source of essential vitamins and mineral elements and provide phytochemicals that play an important role in human health. Increases in global carbon dioxide (CO₂) concentrations and temperature have changed the growth conditions of vegetables. However, the mechanism by which climate change affects vegetable quality is not fully understood. In this paper, the effects of climate change factors, such as CO₂, temperature, and their interactions, as well as their interaction with water and nitrogen (non-climatic factors) on vegetable quality, are briefly reviewed. At present, researches in this field mainly use artificial simulation experiments and crop growth simulation models. Under elevated CO₂ concentrations, the contents of proteins, nitrate, magnesium, iron, and zinc in vegetables decrease, and the antioxidant capacity increases for leafy vegetables and decreases for fruit vegetables. The contents of carbohydrates, vitamins, and phytochemicals (e.g., total glucosinolates, lycopene, and beta-carotene) increase with elevated CO₂. The physiological process may explain why elevated CO₂ levels affect vegetable quality. 1) Elevated CO₂ concentrations promote photosynthesis and thus provide more carbon, increasing the soluble sugar content. 2) Elevated CO₂ enhances the activity of nitrate reductase (NR) and related gene expression, and the increase in carbohydrate content can further promote the transcription and post-translational regulation of NR, which increases nitrate assimilation and reduces nitrate content. 3) Elevated CO₂ also induces the expression of genes involved in ascorbic acid biosynthesis and regeneration, leading to the accumulation of ascorbic acid. 4) The dilution effect, change in nitrogen distribution, decrease in stomatal conductance, respiration, and Rubisco synthesis, and increase in nutrient utilization and root exudates may lead to decreased mineral elements in vegetables under elevated CO₂. Global warming generally decreases vegetable quality. Heat stress restricts photosynthesis by affecting electron transport in photosystem Ⅱ during photosynthesis and the activity of Rubisco in the Calvin cycle dark reaction, affecting vegetable quality. The interaction between elevated CO₂ concentration and increased temperature results in an overall decline in vegetable quality. Reducing irrigation and using a moderate nitrogen supply could improve vegetable quality under elevated CO₂ concentrations. Future vegetable production requires the application of an interdisciplinary and integrated approach that combines physiology and genomics to study the responses of vegetables to climate change.