Simulação do rendimento de grão de arroz irrigado em cenários de mudança climática

Abstract

Climate change projections indicate that current atmospheric CO2 concentrations (380 ppmv) will double by the end of this century, which may lead to an increase in crop yield due to an increase in photosynthesis. However, as a negative consequence of higher CO2 concentration, an increase in atmosphere greenhouse effect and consequent increase in air temperature is expected during the next 100 years, which might offset the positive effects of increasing CO2 on crops. Despite the importance of rice crop in Rio Grande do Sul and in Brazil, there is no report in the literature on the impact of climate change on grain yield for Brazilian genotype and conditions. Thus, the objective of this dissertation was to simulate and evaluate the impact of elevated atmospheric CO2 concentration and temperature increase of +1°C, +2°C, +3°C, +4°C and +5°C. Rice grain yield was simulated with the InfoCrop model. Simulations were performed considering three moderns rice cultivars (IRGA 421, IRGA 417 and EPAGRI 109) and seven sowing dates spaced monthly from 20 July to 20 January. A greater rice grain yield was obtained in the climate change scenarios for the three cultivars, with higher increase for the very early cultivar (IRGA 421) and lower increase for the late cultivar (EPAGRI 109). If global warming takes place, currently sowing period for irrigated rice it may be enlarged.