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Soybean is a very important crop, cultivated mainly as stock feed for animal production, but also for other uses such as biodiesel. Brazil is the second largest producer of soybeans, and the main exporter. About 10% of total Brazilian production is aimed for biodiesel production. The aim of this work was to assess the impact of climate change scenarios on soybean yield and evaluate two simple adaptation strategies: cultivar and planting date. Tests were done for soil profiles from two important producing regions: Chapecó-Red Oxisol, and Passo Fundo-Rodic Hapludox. Two commercial soybean cultivars (CD202 and CD204) and seven regional circulation models (RCM) were used. All simulations were done with DSSAT. After model calibration, eleven planting dates were run for two periods (2011-2040 and 2071-2100) using the RCM's. There were no differences between cultivars. For Chapecó, the majority of RCM's projected yield reductions, with few RCM's projecting increments, and for only few planting dates (November). The response pattern for both time periods were identical, although the end-of-century period presented a further yield reduction. The main reason was reduced water holding capacity in soil, high temperatures, and changes in rainfall distribution along the cropping season. For Passo Fundo, 2011-2040 yields were distinct, depending on the RCM. Simulated yields tended to follow the actual yield pattern along the different planting dates, besides discrepancies. For 2071-2100, all but one RCM indicated yields equal or lower to actual levels. Regarding planting dates, no significant changes were identified, although reductions were observed for the early planting dates (August-September). The scenarios suggest that soybean yields will be reduced, jeopardizing the viability of this crop and biodiesel production in the studied regions.

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