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7. ROLE OF QTLs IN THE EARLY EVOLUTION...
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7.3. RESULTS
7.3.1. Heterosis in intra- and interspecific crosses
All hybrids, either from interspecific crosses or intraspecific ones were fully fertile and
no signs of sterility were noticed. All hybrids were similar or better than parents with regard
to all analysed quantitative characters (Table 7.1). Hybrids had phenotypes of better parents
for 50-60% of characters, from 10% to almost 40% characters were intermediate and for
about 25-30% heterosis occurred (Figure 7.1). In no case, hybrids were worse than parents.
For example, the interspecific hybrid derived from the cross between L. multiflorum and
L. perenne, BR3 x NZ15, was much the same L. multiflorum parent, which exhibited higher
values of analysed traits. However, it has slightly darker leaves that were rather similar to
L. perenne and it has somehow intermediate awns. It also survived winter in a much better
condition than parents. The F 1
and parents of another interspecific combination did not differ
statistically for the majority of characters although the tendency of the hybrid to be similar to
the better parent or intermediate could be realized. The hybrid of L. multiflorum was characterized
by extremely long spike and big basal leaves whereas the highest weight of tillers was
typical of the L. perenne hybrid (Table 7.1).
Heterosis was observed in all intraspecific cross combinations and in an interspecific
one. Only in the cross, HU5 x BO2, the F 1
hybrid did not exceed significantly parents. Frequencies
and the magnitudes of heterosis were similar in inter- and intraspecific crosses.
In total seven traits had higher values in the F 1
from the interspecific cross, BR3 x NZ15
(33%) and five in hybrids from intraspecific crosses (24 and 25%). All these three F 1
hybrids
exhibited heterosis for spike length and green weight of tillers and two of them for dry weight
of tillers (Figure 7.2). Moreover, the interspecific hybrid, BR3 x NZ15 exhibited heterosis for
spikelet and flag leaf traits while the L. multiflorum hybrid for basal leaf traits (Table 7.1). The
unexpected result was obtained for the L. perenne hybrid, in which heterosis was observed
for one of the most important characters differentiating L. multiflorum from L. perenne i.e.,
number of florets per a spikelet. The hybrid had 35% more flowers than the better parent
(Figure 7.2), all the more, numerically the number of flowers was even higher than in the
L. multiflorum hybrid. It is worthy to notice that this trait was intermediate or similar to better
parents in the remaining hybrids (Figure 7.2).
When we turn instead to analysed traits, among 21 of them, 12 exhibited heterosis in
at least one F 1
hybrid. Heterosis for spike characters, weight of tillers and basal leaf traits
was observed the most frequently. The magnitude of increase depended on a trait. The
most extreme values were observed for weight of tillers. Hybrids had higher green weight
of 140-160% and dry weight of more than 200% in comparison with better parents. Surprisingly,
green and dry weight of vegetative parts in any F 1
hybrid did not exceed the values of
parents.