Abstract
In rice, vegetative vigor as a varietal trait is characterized by rapid weight increase, big leaf area, and thin and long leaves at early stage of growth. There exists a negative association between varietal degree of vegetative vigor and the degree of yield response to nitrogen application. In the vast genetic diversity of tropical rice varieties, vegetative vigor and growth duration are two major genetic measures in ecological reactions. Varieties with high vegetative vigor and long growth duration have poorest nitrogen response in grain yield.
