Potential forcing of CO2, technology and climate changes in maize (Zea mays) and bean (Phaseolus vulgaris) yield in southeast Brazil

Based upon sensitivity experiments, this study aims to investigate the impact of increased atmospheric CO2 concentration, climate changes, and ongoing technological advancements on bean (Phaseolus vulgaris) and maize (Zea mays) yield. This investigation assumes that the atmospheric CO2 concentration evolves according to the A2 scenario. For these analyses we have used climate data as projected by climate simulations conducted with the HadCM3 climate model for both present day and greenhouse warming conditions. The results demonstrated that warming conditions associated with increased greenhouse gases as delivered by the HadCM3 model lead to reductions in the potential productivity of maize and beans for the years 2050 and 2080 by up to 30%. This thermal response is, however, damped by the highly efficient CO2 fertilization effect which is expected to increase bean productivity as compared to present day conditions. A similar investigation for maize yield revealed a different picture. It has been found that the CO2 fertilization feedback is much weaker and cannot cancel out the thermal effect. We have found, therefore, that climate changes as simulated to occur in the future are not favorable for increasing the maize yield in southeast Brazil. By the inclusion of the third forcing evaluated, representing technological advancements, it is demonstrated that improvements in the crop system reduce the negative effect associated with warmer climate conditions for both crops. We conclude that appropriate soil and technological management as well as genetic improvements may very likely induce an increase in bean and maize yield despite the unfavorable future climate conditions.