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

part <strong>of</strong> that period is nost critical.
From a breeeling viewpoint, this type <strong>of</strong> cross rnight be
useful in attempting to develop genotypic combínations
particularly suÍted to the environmental- condi*ions normally
encountered during the barley growing season in i.festern
Canada. this anthor feels that the post_anthesis period is
critical, particularly in relation to the climatic pattern.
0f this period, the first part is the most criticaL, since,
in the area in question, heading time and the period foì--
lowing that are nornar fy the warmest, clríest parts <strong>of</strong> our
growing season. fherefore a genotype which headed earlier
could take advantage <strong>of</strong> slightly less stressfull growing
conditions fo!. a few more days than one which headed later"
During years when conditions are more optinum for a longer
part, or all <strong>of</strong> the post-anthesis period, such a genotype
should still be superior to a later heading type. It is
also reasonable to expect that, regardless <strong>of</strong> environmental
conditions, in terns <strong>of</strong> kernel quality such a genotype
would be generally at an advantage.
The preceeding discussÍon also illustrates some <strong>of</strong> the
reservations one rnust have regarding eorrelation values,
particularly when sample sizes are large. It is not always
a simple task to define cause and effect rel_ationships which
can be very complex, involvÍng the simultaneous effects <strong>of</strong>
several traits. Such complexity was obvious in the inter_
pretatíon <strong>of</strong> these data; since few relatlonships, although
significant, were strong; and j.ndiviitual parameters were
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