Effects of reduced plant height on breeding requirements and ...

while the tall sho\^/ed virtually no yield difference between
]-39
the narrowest and the intermediate spacings" Similar
results v,¡ere reported from a wheat study b¡, Stoskopf (Lg6?) "
Ä significant genotype x seeding rate x row spacing
interaction occurred at Õarman (ra¡re 56). This interaction
wâs due to Bonanza consistently outyielding the semi_dwarf
at al-Ì levels <strong>of</strong> al_l seeding-rate - rovr'_spacing combinations
except for the combination <strong>of</strong> the narrowe st row space and
the highest seedíng rate. At this treatment co¡nbination
Minn 64-62 outyierded Bonanza by an amount equal to that by
which the reverse had Õccurred at all other treatment
co¡nbinations. This effect was probably due to the adverse
growth conditions at this site, resulting in particular
stress on the seni-dwarf due to earty weed competition. At
the narrow row spacing and higher seeding rate the semi_
dwarf was able to compete with the weeds as well as the
tal1 genotJrpe and thu.s yielded rnore grain at thât treatrnent
combination. Similar results were reported from a ,¡rheat
study (You.ng and Bauer, Ig?3),
Spikes ner ünit Area
At Sanford and lfinnipeg the semi-dwarf had significantly
more spikes per unit area than the tall (Table 5B),
In agreement with the findings <strong>of</strong> Guitar.d et q!. (]961)
a positive effect on spikes per unit area resulted from
íncreased seedì-ng rates (fable 59), atthough the ehange was