Since the early 1990s, liberalization of the seed market in Tanzania has attracted several foreign companies that now market maize hybrids in the country. In this article, we analyze the impacts of proprietary hybrids on maize yields, production, and household living standards. We build on a recent survey of smallholder maize farmers in two zones of Tanzania. Hybrid adoption rates are 48% and 13% in the North and East, respectively. Average net yield gains of hybrids are 50-60%, and there are also significant profit effects.

While several studies have shown that genetically modified Bt cotton can benefit smallholder farmers economically, the sustainability of these effects is still unclear and debated controversially between biotechnology proponents and critics. We use unique panel data of 533 cotton farmers, collected in India between 2002 and 2008, to analyze Bt impacts on cotton yield, profit, and household living standards. Results from fixed effects models show that the adoption of Bt cotton is associated with a net yield gain of 24% and a profit increase of 50%.