‘Second-generation’ MVs and the evolution of the Green Revolution: the case of Central Luzon, 1966–90

By now new modern rice varieties (MVs) with multiple pest and disease resistance have completely replaced early MVs, such as IR5 and IR8, except in a few areas of Asia. This study attempts to identify the changing impacts of ‘first-generation’ and ‘second-generation’ MVs on productivity in rice farming by estimating the yield function, while correcting selectivity bias arising from the choice of varieties. For this purpose, we used farm-level survey data collected for eleven cropping seasons in Central Luzon in the Philippines from 1966 to 1990. We found that while the yield advantage of first-generation MVs over traditional varieties was limited, the yield-increasing effect of second-generation MVs over first-generation MVs was highly significant. In particular, the adoption of improved MVs significantly contributed to yield growth under the irrigated condition and during the dry season. Thus, we conclude that the Green Revolution would not have been revolutionary without the development and the diffusion of second-generation MVs with multiple pest and disease resistance.