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

could in part account for the poor showing <strong>of</strong> the semi_
dwarfs. 0n the other hand, a símilar argument holds for
the low yield <strong>of</strong> the best ta1l line ín C_?O-),
0vera11, it appears reasonable that intensÍve serection
<strong>of</strong> short types, thereby provi.d.lng Larger numbers <strong>of</strong> lines to
test for yie1d, would greatly enhance progress toward short,
htgh yielding genotype s, since the small sample obtaÍned
randoml-y in the present study contained. some good materiar.
Statistically, since both Bonanza and Minn6 4_62 are
homozygous and their mean yields were calculated from large
nurnbers <strong>of</strong> pLots at each site, their standard errors should
be a good estirnate <strong>of</strong> the envÍronmental error for yield over
the whole study. With this standard error a least signífi-
cant difference for yieJ-d could be computed. Such computa_
tion gave a least significant difference equal to 1l_0 grans
per plot. 0n this basis, there were no significant differ-
ences between the hlghest yielding lines: among the <strong>height</strong>
categories, among the populations, or across the whole experinent.
This result again stresses the need for further,
more effective' yield testing <strong>of</strong> this rnaterial and indicates
the inadequacy <strong>of</strong> the techniques used to characterize the
true yieldíng ability <strong>of</strong> these genotypes.
The population nean ptant <strong>height</strong>s and yietds ind.ícated
the possibility <strong>of</strong> yíetd potential in the short strawed
materiaL. Although the mean <strong>height</strong> <strong>of</strong> e-?O-3 was signifi_
cantly shorter than for C-ZO-L, C-?O-Z and Bonanza (ín fact
C-7O-3 contained. no line as talL as Bonanza), it's mean
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