Seed quality under elevated CO2 differs in soybean cultivars with contrasting yield responses

Authors: DIGRADO, ANTHONY - University Of Illinois; Montes, Christopher; BAXTER, IVAN - Danforth Plant Science Center; Ainsworth, Elizabeth - Lisa

Submitted to: Global Change Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/11/2024
Publication Date: 2/6/2024
Citation: Digrado, A., Montes, C.M., Baxter, I., Ainsworth, E.A. 2024. Seed quality under elevated CO2 differs in soybean cultivars with contrasting yield responses. Global Change Biology. 30(2). Article e17170. https://doi.org/10.1111/gcb.17170.
DOI: https://doi.org/10.1111/gcb.17170

Interpretive Summary: Growth at elevated carbon dioxide concentrations can decrease the nutritional content of grains. However, the physiological mechanisms causing the nutritional decline are largely unknown. In this study, we investigated two soybean cultivars with different yield responses to rising atmospheric carbon dioxide to test if a decline in nutrient content is associated with a large increase in yield. We found that seed quality responded differently to elevated carbon dioxide in the two cultivars and that elements were differently impacted. Aluminum, calcium, iron and selenium decreased in elevated carbon dioxide, but phosphorus and manganese were unchanged. Seed protein content increased under elevated carbon dioxide while oil content was negatively related to yield. Despite the decline in the seed concentration for some elements, the overall yield per hectare of elements, protein, and oil increased at elevated carbon dioxide concentrations because of greater seed yield. We quantified the potential economic impacts of altered seed composition in the future and estimate that declining oil content with increasing soybean yield could negatively impact future profits.

Technical Abstract: Reduced grain and seed nutrient content in crops grown under elevated CO2 concentrations (eCO2) have raised concerns about future food and nutrition security. Studies have reported that different seed elements responded differently to eCO2, and the nutrient response to eCO2 varied across species and cultivars. This study investigated the response of seed quality in two soybean cultivars (HS93-4118 and Loda) previously shown to have different yield responses to eCO2. We show that seed quality responded differently to eCO2 for the two cultivars and that elements were differently impacted. The strongest declines under eCO2 were observed for Al, Ca, Fe, and Se while P and Mn were unaffected. Seed protein content increased under eCO2 for the two cultivars. Oil content, however, showed a negative relationship with yield and declined under eCO2. Using path analysis, we show that eCO2 reduced the seed content for some elements through increasing seed yield, effectively diluting the elemental concentrations, while other elements were reduced in a yield-independent manner. Despite the decline in the seed concentration for some elements, the overall yield per hectare of elements, protein, and oil under eCO2 increased because of greater seed yield. We quantified the economic impact of altered seed composition and show that the decline in oil content with increasing soybean yield at eCO2 could negatively impact future profits.