Conditional heterosis
Analysis of the conditional heterosis of plant
height at different developmental stages (Fig. 3-B)
showed that, in most of the periods, the conditional
HMP (HMP(t|t-1)) of the two groups was positive at
significant or extremely significant levels, and the
conditional HBP (HBP(t|t-1)) was negative at significant or
extremely significant levels. This suggests that HMP and
HBP exhibited some new performances at different
developmental stages with the variations of level and
direction. As far as the HMP(t|t-1), two groups represented
the same trend: firstly decreased, then increased, and
then decreased and increased again, the comparatively
large values both appeared at S4|S3 and S7|S6. This
was why HMP of the two groups increased greatly from
S3 to S4 and from S6 to S7. For the HBP(t|t-1), it
decreased at first, increased subsequently, then decreased,
and being steady at last developmental stage for the
two groups. The HBP of the first group kept stable due
to smaller changing range of HBP(t|t-1) (from -1.61% to
-0.62%) during the investigation. The HBP(t|t-1) of the
second group ranged from -1.77% to -0.32%, and then
stabilized after S5|S4, which explained why HBP was
stable after S5. The HBP(t|t-1) of S2|S1 and S3|S2 were
higher than those of other periods in the second group,
and then the corresponding HBP increased greatly before
S3. The above analysis indicates that the variation
trend of conditional heterosis at different developmental
stages could reasonably elucidate the corresponding
variation trend of unconditional heterosis.