Wheat Rusts and the Costs of Genetic Diversity in the Punjab of Pakistan
用公共品理论解释农民为何不种植社会最优抗锈水平的小麦品种，并分析增加遗传多样性的三种策略及其产量代价。
Abstract The theory of impure public goods is used to demonstrate why farmers may not grow wheat cultivars with the socially desirable level of rust resistance. First, they may grow cultivars that are high yielding though susceptible to rust. Second, many farmers may grow cultivars with a similar genetic basis of resistance. Expected rust losses can be reduced by ( a ) more diversified genetic background in released wheat cultivars; ( b ) greater spatial diversity in planted cultivars; or ( c ) use of a temporally changing list of cultivars known to be rust resistant. Yield trade‐offs associated with these policies illustrate potential costs of increasing genetic diversity.