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

lower seedíng rates gave higher yields when weeds and insects
were controlled, especially in years with severe moisture
stress. He used seeding rates ranging from 22 to IOI Ug,t/na,
He noted that <strong>plant</strong> survival and tillering nade up for 1ow
rates, and overall there were no differences in the number
<strong>of</strong> mature kerne Is per unit area.
Some i-nvestigations have revealed cultívar by seeding
rate interactions for yie1d. In reporting on a seeding rate
and row spacing wheat study Briggs (I9? 5) stated, "In view
<strong>of</strong> the differences j.n c ultivar response to seeding rates
for the important agronomic characteristics studied here,
it ís suggested that all newly lícensed cultivars <strong>of</strong> wheat
should be subjeeted to this type <strong>of</strong> tesi, particularly íf
they are <strong>of</strong> a novel germplasm type.rt, Such would be the
case with semi-dwarf genotypes.
Cultivar by seeding rate interactions for yield have
been reported for barley (Demirlicakmak et a!,, 1963) , for
sorghum (Stickler and Younis, 1966), and wheat (lv¡alih, t969¡
ãei.d.an, f9?4). the sorghum and wheat studies involved tall
and semi-dwarf genotype s and the interaction was due to
shorter genotypes performing better than tal-ls at greater
<strong>plant</strong> densities. Other reports ( cuitard. et aI., lg6li
McFadden, l-970; Cl-ements e! ù," 1974¡ Briggs, 1975¡ Fischer
et a1" , L9?6) indicated no interacti-on. Two <strong>of</strong> these studies
involved short stature genotJrpes, one exclusively (Fischer
et a1. , 1976) and one a range <strong>of</strong> tall and short genotypes
(Clements et 41, , L974),
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