Elevated Carbon Dioxide Level Suppresses Nutritional Quality of Lettuce and Spinach

Abstract

Rising global CO 2 levels are a major factor that impacts not only the environment but also many plant functions including growth, productivity and nutritional quality. The study examined the impact of elevated [CO 2 ] on nutritional quality and growth characteristics of lettuce (Lactuca sativa) and spinach (Spinacia oleracea). Elevated [CO 2 ] decreased the concentration of many important nutrients including nitrogen (protein), potassium and phosphorus in the edible parts of both lettuce and spinach. The nitrogen concentration in lettuce shoots was reduced by more than 30% at elevated [CO 2 ] compared to the plants grown at ambient level of CO 2 . Similarly the concentration of a number of micronutrients including sulfur, zinc, copper and magnesium, was depressed in lettuce shoots. Although the total phenolic content and antioxidant capacity were higher in lettuce at elevated CO 2 , they were not affected in spinach. The photosynthetic activity was variable among the plant species while there was no increase in the carbon accumulation in these plants at elevated [CO 2 ]. However, there was significant reduction in the leaf stomatal conductance in both lettuce and spinach in response to higher [CO 2 ], which is likely affect both water loss from the leaves and their photosynthetic activity. The results indicate a broad adverse impact of rising [CO 2 ] on the nutritional quality of commonly consumed leafy vegetables namely, lettuce and spinach.

Elevated and super‐elevated CO2 differ in their interactive effects with nitrogen availability on fruit yield and quality of cucumber

“…Additionally, CO 2 enrichments decreased protein concentration (Fig. f), consistent with several other studies in grains and other vegetables . Although cucumber is not the main protein source, the decreased protein concentration in both vegetables and grain crops potentially accelerates the imbalance in energy and protein uptake, particularly for vegans …”

“…wheat, rice, and sorghum) and vegetables (e.g. lettuce, sweet pepper, and carrot and turnip). This similarity gives us a warning that the deficiency of Fe and Zn could possibly impose an inevitable threat to human nutrition from the consumption of either grain crops or vegetables if breeders or producers continue focusing on increasing vegetable yield in the future.…”

“…2f ), consistent with several other studies in grains 19 and other vegetables. 43,50 Although cucumber is not the main protein source, 51 the decreased protein concentration in both vegetables and grain crops potentially accelerates the imbalance in energy and protein uptake, particularly for vegans. 52 Super-elevated CO 2 compared with other CO 2 treatments did not concentrate minerals in high N availability as predicted.…”

Assessment of grain quality in terms of functional group response to elevated [CO2], water, and nitrogen using a meta‐analysis: Grain protein, zinc, and iron under future climate

“…Recently, Loladze () demonstrated that e[CO 2 ] reduced wheat grain protein and nitrogen concentrations. Similarly, studies by Taub et al (), De Graaff, Van Groenigen, Six, Hungate, and van Kessel (), Conroy (), and Giri, Armstrong, and Rajashekar () investigated the response of grain protein to e[CO 2 ] under different N regimes. Several experiments were carried out to investigate the responses of biomass and productivity to e[CO 2 ] among different functional groups (Hooper & Vitousek, ; Reich et al, ).…”

Elevated CO<sub>2</sub> Levels Affect Phytochemicals and Nutritional Quality of Food Crops

“…Diminished nitrogen content of plants, which mostly reflects on their protein content, is a major concern as it plays an important role in the human diet. Malnutrition and showed a significant decrease in a number of major and micronutrients including protein and zinc [36]. In a meta-analysis of nutritional quality of many food crops as affected by elevated CO 2 , Loladze [37] showed that the overall pattern in many C 3 plants was that elevated CO 2 depressed not only nitrogen but many other nutrients including iron, zinc, calcium, potassium, sulfur and other micronutrients.…”