the third irrigation scenario is designed to test the effects of interaction between the irrigation efficiency and irrigation expansion scenarios in addition there are also international spillover effects world prices for maize and wheat are lower by and respectively compared to scenarios where the improved varieties are adopted only in the united states and by and respectively when adopted throughout the oecd figure for those regions that are currently battling water stress eg the mediterranean irrigation efficiency measures contribute to improved yields on the order of between and in irrigated areas growing mainly maize and vegetables