Genetic Experiments on Hybrid Vigor in Maize

In the first section a biometrical study of the genetic nature of hybrid vigor in maize is reported. From two vigorous F1 hybrids, data on F2 yields (individual ear weights) show practically no skewness. If hybrid vigor is due to dominant size genes, some reason for the absence of F2 skewness is necessary. The most probable cause is demonstrated by an analysis of the component parts of ear weight. Both ear length and ear diameter show significant negative skewness values, while number of kernel rows shows a positive skewness. Accordingly, the absence of skewness in yield itself may be attributed to a balance of genes, some of which exhibit dominance for large size and some for small size. The above situation is also indicated by multiple correlation studies of ear length, diameter and kernel rows with ear weight as the dependent variable. The partial regression coefficients (or path coefficients) indicate that both ear length and ear diameter have a high, positive influence on ear weight, whereas number o...