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

Reports on the effect <strong>of</strong> seeding rate on the yield
c ornponents have indicated that increasing seeding rate gave
rise to increased number <strong>of</strong> <strong>plant</strong>s per unit area, and fewer
spikes per <strong>plant</strong>, associated with decreased numbers <strong>of</strong> ker-
nels per spike and weight per kerne). (Guitard et al. , J-96l-),
ïncreased seed rates gave increased nunber <strong>of</strong> spikes per unit
area by the increased number <strong>of</strong> <strong>plant</strong>s being greater than
losses due to fewer spikes per pIant. Results from work with
bartey by Bockstaele and Maddens (f966), Kirby (t96?), nay
and îhompson (1970), and Willey and Holtiday (1971)¡ work
with wheat by Malik (L969), Zeidan (f9?4), and Fischer É 4.
(A9?6); ând work wlth oats by Jones and Hayes (196? and L96B)t
are essentially in agreement with Guítard e! al. Middleton
et aI. (L964), working wíth barley, found the same with the
exception <strong>of</strong> no change in kernel weight over densitÍes.
Briggs (l.9?5) also reported no effect <strong>of</strong> densities on kernel
weight in wheat, while Woodv¡ard (1956) reported increased
seeding rates gave smaller spikes and smalfer kernels, YieId
reduetions at above -optimum seeding rates are due to eontin-
uing decreases Ín kernels per spike and kernel weight with no
further increase in spíkes per unit area to compensate for
the }osses Ìn the other cornponents (Willey and Holliday,
L97L), As previously stated, PeJ"ton (f969) indicated that
<strong>plant</strong> survival and tlllering (Í.e., inereased spikes per unit
area) can compensate to maintaln yields at lower seeding
rate s .
Increased seeding rates have been reported to lead to
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