Effect of environmental changes on vegetable and legume yields and nutritional quality

Abstract

Environmental changes threaten agricultural production, food security, and health. Previous reviews suggest that environmental changes will substantially affect future yields of starchy dietary staples. To date, no comprehensive global analysis of the impacts of environmental change on (nonstaple) vegetables and legumes-important constituents of healthy diets-has been reported. We systematically searched for articles published between 1975 and 2016 on the effects of ambient temperature, tropospheric carbon dioxide (CO₂), and ozone (O₃) concentrations, water availability, and salinization on yields and nutritional quality of vegetables and legumes. We estimated mean effects of standardized environmental changes using observed exposure-response relationships and conducted meta-analyses where possible. We identified 174 relevant papers reporting 1,540 experiments. The mean (95% CI) reported yield changes for all vegetables and legumes combined were +22.0% (+11.6% to +32.5%) for a 250-ppm increase in CO₂ concentration, -8.9% (-15.6% to -2.2%) for a 25% increase in O₃ concentration,-34.7% (-44.6% to -24.9%) for a 50% reduction in water availability, and -2.3% (-3.7% to -0.9%) for a 25% increase in salinity. In papers with baseline temperatures >20 °C, a 4 °C increase in temperature reduced mean yields by -31.5% (-41.4% to -21.5%). Impacts of environmental changes on nutritional quality were mixed. In a business-as-usual scenario, predicted changes in environmental exposures would lead to reductions in yields of nonstaple vegetables and legumes. Where adaptation possibilities are limited, this may substantially change their global availability, affordability, and consumption in the mid to long term. Our results stress the importance of prioritizing agricultural developments, to minimize potential reductions in vegetable and legume yields and associated negative health effects.

Keywords: environmental exposure; legumes; nutritional quality; vegetables; yields.

Fig. 1.

PRISMA chart showing the number of papers in each search stage. *Combined with a systematic review on fruits; the systematic review on fruits to be published elsewhere. **Two papers analyzed both fruits and vegetables/legumes.

Fig. 2.

Overview of field and greenhouse studies per country. Field studies are divided into those assessing the impact of environmental changes on nutritional quality (blue), yield changes (green), or both (yellow).

Fig. 3.

Dot plot (A) and forest plot (B) showing the available experimental evidence of yield changes in vegetables and legumes resulting from a standardized increase of 250 ppm CO₂ concentration. More details of the forest plot are provided in SI Appendix.

Fig. 4.

Dot plot (A) and forest plot (B) showing the available experimental evidence of yield changes in vegetables and legumes resulting from a standardized 25% increase in O₃ concentration (plot B: legumes only). More details of the forest plot are provided in SI Appendix.

Fig. 5.

Dot plot showing the available experimental evidence of yield changes in vegetables and legumes resulting from a standardized 50% reduction in water availability.

Fig. 6.

Dot plot showing the available experimental evidence of yield changes in vegetables and legumes resulting from a standardized 25% increase in water salinity.