Path analysis of traits affecting grain yield and its components in corn

An advantage of path analysis over correlation analysis in determining relationships among plant traits is that the traits are arranged in a path diagram that shows their cause-and-effect relationships. A path analysis study involving yield and yield-related traits of corn(Zea mays L.) cultivars grown in the Philippines has not yet been conducted and results from a study of this nature would be useful in corn breeding and production. This study aimed to use path analysis in determining the important traits that affect corn grain yield during the dry and wet seasons in the Philippines. Grain yield and 13 yield-related traits (plant and ear height, days to silking, stalk circumference, leaf area index at 30 days after planting and at tasseling, number of ears per plant, ear length and circumference, length and number of grain rows, and the masses of ears and grain) were organized into a path diagram based on the structural organization of the corn plant. Data for these traits were obtained from 11 corn hybrids grown during the 2002 dry and wet season field experiments at the University of the Philippines Los Baños. Correlation analysis indicated that ear length and mass were consistently related with grain yield in both seasons. On the other hand, path analysis indicated that high ear mass, grain row length, grain mass, and ear length increased grain yield in both seasons. Furthermore, thick stalk increased grain yield only during the dry season, while more ears per plant increased grain yield only during the wet season. The results of this study can serve as a guide to corn breeders in selecting high yielding genotypes during the dry and wet seasons. It also suggests to the farm managers that optimal growing conditions should be provided to the corn crop during the growth and development of important yield-related traits.