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

icularly when nore optimum growing conditions may be
encountered.
YieLd
Response to applied N was similar at al,l sites: large
and signifícant increases with the first N incrernent, follow-
ed by continuous but progressively snaller gains as N 1evels
increased" The combined effects <strong>of</strong> the lower original soil
N level and the weed ínfestations at Carman, which at the
zero applled N level severely suppressed the growth <strong>of</strong> the
barJ-ey; ted to significant and large yield response to N at
that location in both years. fhj-s was particularly so in
t}r.e L975 test, in which the wild oats and green foxtait
l"owered yields nost severely when fertility was inadequate "
lhese stress factors were reflected in overall lower yields
at Carnan in both years, but particularly in 19?5 when atl
genotypes yielded very poorly. This, in turn, gave rise to
no signlficant yieLd dÍfferences between genotypes in that
experinoent.
At the other sites the two tal1 genotypes and Minn64-62
produced the híghest yields, whíle yields <strong>of</strong> the other two
seni-dwarfs were lower. The lower yield <strong>of</strong> these 1atter
genotypes was responsible for the significantly lower yield
<strong>of</strong> the semi-dwarfs as a group at thrèe <strong>of</strong> the four sites
where this was the case, lhe lower yielding semí_dwarfs
matured earlíer than Bonanza i¡rhereas the higher yielding
Minn64-62 was later maturing, Since early rnaturity is
20I