The Impact of Increased CO(2) and Drought Stress on the Secondary Metabolites of Cauliflower (Brassica oleracea var. botrytis) and Cabbage (Brassica oleracea var. capitata)

Elevated carbon dioxide and drought are significant stressors in light of climate change. This study explores the interplay between elevated atmospheric CO(2), drought stress, and plant physiological responses. Two Brassica oleracea varieties (cauliflowers and cabbage) were utilized as model plants. Our findings indicate that elevated CO(2) accelerates assimilation rate decline during drought. The integrity of photosynthetic components influenced electron transport, potentially due to drought-induced nitrate reductase activation changes. While CO(2) positively influenced photosynthesis and water-use efficiency during drought, recovery saw decreased stomatal conductance in high-CO(2)-grown plants. Drought-induced monoterpene emissions varied, influenced by CO(2) concentration and species-specific responses. Drought generally increased polyphenols, with an opposing effect under elevated CO(2). Flavonoid concentrations fluctuated with drought and CO(2) levels, while chlorophyll responses were complex, with high CO(2) amplifying drought’s effects on chlorophyll content. These findings contribute to a nuanced understanding of CO(2)–drought interactions and their intricate effects on plant physiology.