Adapting irrigated and rainfed wheat to climate change in semi-arid environments: Management, breeding options and land use change.

• Mexico's wheat production is likely to decline under future climate change. • Expanding wheat area to recently used land for wheat may be the most effective adaptation strategy to combat production loss from future climate change. • Combining new adaptive crop genetic traits with increased N fertilizer will also improve yield for irrigated and rainfed wheat for current and future climate scenarios. Mexico's 3.3 million tons current wheat production is projected to decline due to climate change. To counteract these negative impacts, we explored a range of plausible adaptation measures including change in crop management (early sowing and nitrogen fertilizer applications), crop genetic traits (early vigor, late flowering and heat tolerance) and wheat growing area expansion. Adaptation measures were simulated individually and in various combinations with a multi-crop model and multi-Global Climate Model ensemble across representative wheat growing regions and aggregated to national wheat production. Under both baseline (current) and future climate scenarios, most of the suggested individual and combined genetic traits resulted in a positive impact on irrigated wheat but were less beneficial in rainfed systems, with the largest responses observed with late flowering and increased N fertilizer. Increased N fertilizer applications on its own, but particularly combined with crop genetic traits showed the highest yield increase in the baseline, with further positive impacts in the future scenarios. Yield benefits from new crop genetic traits combined with increased N fertilizer applications could add about 672,000 t year−1 to national wheat production, after losing 200,000 t year−1 due to climate change by 2050s. Most effectively, expanding wheat to include all areas where wheat was previously grown during the last two decades could add 1.5 million t year−1 now and 1.2 million t year−1 in the future. Breeding for new crop genetic traits will reduce some of the negative impacts from future climate change, but improved cultivars need to be implemented with suitable crop management, especially N fertilizer management. [ABSTRACT FROM AUTHOR]