Intensifying drought eliminates the expected benefits of elevated carbon dioxide for soybean

Abstract

Stimulation of C3 crop yield by rising concentrations of atmospheric carbon dioxide ([CO2]) is widely expected to counteract crop losses that are due to greater drought this century. But these expectations come from sparse field trials that have been biased towards mesic growth conditions. This eight-year study used precipitation manipulation and year-to-year variation in weather conditions at a unique open-air field facility to show that the stimulation of soybean yield by elevated [CO2] diminished to zero as drought intensified. Contrary to the prevalent expectation in the literature, rising [CO2] did not counteract the effect of strong drought on photosynthesis and yield because elevated [CO2] interacted with drought to modify stomatal function and canopy energy balance. This new insight from field experimentation under hot and dry conditions, which will become increasingly prevalent in the coming decades, highlights the likelihood of negative impacts from interacting global change factors on a key global commodity crop in its primary region of production.

Disaggregating sorghum yield reductions under warming scenarios exposes narrow genetic diversity in US breeding programs

“…An alternative route to minimize future heat-stressinduced yield losses could entail the introduction of greater chilling tolerance during germination and early seedling establishment, thereby facilitating earlier planting at lower soil temperatures to escape the more extreme heat stress that is currently coinciding with sensitive growth phases. Our findings are relevant for moderate-to high-yielding nonirrigated production environments, and we do not account for potential fertilization effects of increased CO 2 concentrations associated with global warming (33)(34)(35)(36)(37)(38). Future studies focusing on long-term climatic responses of crops under severe stress conditions would need to exercise appropriate measures to account for increasing atmospheric CO 2 and its interactions with other factors influencing yield response.…”

Crops, Nitrogen, Water: Are Legumes Friend, Foe, or Misunderstood Ally?

“…A controlled-environment study of WUE i in soybean noted that g s , much more than A, dictates WUE i [14]. Another recent study showed that the expected benefits of rising atmospheric CO 2 concentration did not eventuate, owing to modified stomatal function and canopy energy balance [59]. One of very few direct comparisons of C 3 grasses (including cereals) with legumes, revealed that A was related to N per unit leaf area (N area ) for both groups, but that A was consistently greater in C 3 grasses than in legumes [60].…”

Using Biotechnology-Led Approaches to Uplift Cereal and Food Legume Yields in Dryland Environments

“…Rising CO 2 may compensate for losses due to drought in some situations. However, a recent study – conducted over eight years under varying precipitation and with year-to-year variation in weather at a unique open-air field facility – revealed that stimulation of soybean yield by eCO 2 diminished to zero as drought intensified and eCO 2 interacted with drought to modify stomatal function and canopy energy balance (Gray et al, 2016). eCO 2 did not stimulate photosynthesis, biomass or grain yield, whereas the treatment combining eCO 2 and high temperature reduced grain yield in maize (Ruiz-Vera et al, 2015).…”