HETEROSIS AND NUCLEAR-DNA CONTENT IN MAIZE

Twenty-five F1 maize hybrids were analysed with respect to their nuclear DNA content. Twelve of the hybrids have been reported previously to have a low heterotic response while 13 have a high heterotic response. The nuclear DNA content of each F1 hybrid was compared with the midpoint DNA amount of its respective parents. In nine of the hybrids with the low heterotic response, the observed nuclear DNA amount exceeded the expected DNA amount by approximately 5 per cent. In 12 of the 1 3 hybrids that had a high heterotic response, the observed nuclear DNA amount was not significantly different from the expected DNA amount. These results demonstrate an association between heterotic response and nuclear DNA content inheritance in F1 hybrids of maize.