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

score and yield on a rank correlatÍon basis, hinted at the
possibility <strong>of</strong> using thís parameter as a selection criterion.
For this to become a reality, further and more extensive re_
search would have to ìre carried out in that area.
llhe laek <strong>of</strong> association between coleoptile length and
emergence rate index for these genotJ¡pes is encouraging.
llowever, the method. <strong>of</strong> determination and the limited scope
<strong>of</strong> the study involved in the calculation <strong>of</strong> emergence rate
index, as well as the use <strong>of</strong> rank correlation procedures,
were lnadequate to obtain conclusive results.
One <strong>of</strong> the fears expressed by several dryland area <strong>plant</strong>
breeders regardlng semÍ-dwarfs is that the root systems <strong>of</strong>
these genotypes may not be adequate to withstand the drought-
hy conditions <strong>of</strong>ten encountered.
Al,though not statistícally significant, d.ue to the dif_
ficulty invoÌved in the measurement <strong>of</strong> these paraÍieters, the
trends which developed indicated that, for these genotypes,
the fears <strong>of</strong> the breeders may be justified. rhe semí-dwarfs
apparentl-y had both smaller and slower-growing root systems"
0f particular note was the tendeney <strong>of</strong> the semi-d.warfs to
show drastically <strong>reduced</strong> root growth rates at week seven,
whiLe the tal1s did not show this reduction until week nine.
This rnay in part be assoclated. with the tendency for the
speeífie semi-dwarfs studied to ripen <strong>of</strong>f quickly.
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