early and middle stages and stabilized after S5, with
the minimum of 3.78% at S3 and the maximum of
5.58% at S1; in the second group, it gradually
increased at the early and middle stages and stabilized
after S5, with the minimum of 4.83% at S1 and the
maximum of 12.36% at S7. As a result, the first group
had stable HBP during the whole growth periods, and
the HBP of the second group increased constantly at the
early and middle stages, and became stable at the later
stages. Both HMP and HBP decreased slightly and then
increased gradually with the plant development in the
first group, but increased in the whole developmental
stages in the second group. These results are consistent
with the conclusions from conditional and unconditional
variances analyses, that is, the plant height in the first
group was mainly affected by the additive effect at the
early stage, and by the dominant effect at the later
stages, whereas in the second group, the plant height
was mainly affected by the dominant effect in the
whole periods. This also confirms that the abundant
expressions of dominant effect genes could advance
the heterosis. In general, F1 had the best heterosis in
the whole developmental stages, especially at the later
stage. Consequently, more attention should be paid to
the management of fertilizer to obtain moderate plant
height, which not only forms the foundation of high
yielding, but also improves the lodging resistance.