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

was significant for Ç-?A_2, indícating a need. to test for
yield at more than one locatíon and for more than one year.
Signíficant levels orAfr" anoufr, for Ç-?o-3 led to a
sinilar conclusÍon. In thís case these interactions, com_
bined with the large error conponent, in fact gave rise to
a heritability (28 + ZZ,O) essentially equal to zero, despite
the fact that this population had the largest yield range
(îable 9) "
The overâIl result suggests that, with the possible
exception <strong>of</strong> A-lO-2, the rnethodology enployed was inad.equate
for a precise assessment <strong>of</strong> the yieLding ability <strong>of</strong> these
l1nes. îo overcome this probJ.em, ways <strong>of</strong> reducing the error
varíance would havê to be found" In view <strong>of</strong> the very large
numbers <strong>of</strong> 1i.ne s involved a design utilizíng bJ"ocking within
replications, as weI)- as increased plot size and number <strong>of</strong>
repLicatÍons, mlght arso have aided in reducing this error.
ft also appeared from the significance <strong>of</strong> the various
genotype by environnent interactions in C_?O_Z and C-?0_3
that the utility <strong>of</strong> more environments increased as the
number <strong>of</strong> lines tested decreased, Thís may be largely the
effect <strong>of</strong> redueed range <strong>of</strong> varlability concurrent with the
deerease in Llne numbers, thus increasing the impact <strong>of</strong> a
large error term in distinguishång differences.
The results <strong>of</strong> this experíment nay have limited
application with respect to general yield testing in barley,
because the genetic varÍances and ranges <strong>of</strong> yield obtained
were greater than those normally encountered in eritieaL
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