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

inheríted" observation <strong>of</strong> thÍs materíal indicated the
i-nf luence <strong>of</strong> mod if ier gene s which led to the occ u*ence <strong>of</strong>
stable genotypes <strong>of</strong> íntermediate <strong>height</strong> as welL as reeovery
<strong>of</strong> the parental classes. These interrûediate <strong>height</strong> geno-
tl¡pe s were in fact the most agronomically desirabLe group
ín the present etudy.
?he resuLts fro¡n alI three populations investigated,
in particular c-lo-J, indicated. that lines with a desrrabLe
combinatlon <strong>of</strong> performânce characteristÍcs occured wíth
greatest frequency among genotypes ln thi_s Íntermediate
<strong>height</strong> category. lhese lines had improve¿l straw strength
relatlve to the talLer lines, yet also had acceptable leve1s
<strong>of</strong> yieLd and kernel size paramete!.s and more acceptabLe
maturity. This was exemplified by C-|O-J, in which the
majority <strong>of</strong> derived lines fell in the intermediate <strong>height</strong>
class. Despite this.the populati.on means and ranges for
most <strong>of</strong> the other eharacteristics were similar to those
obtained among lines from the other two crosses, lodging
being an exeeption, but on the favourable side (fables g
and 9).
The high heritabitity <strong>of</strong> <strong>plant</strong> <strong>height</strong> and the lack <strong>of</strong>
conpetitive ability <strong>of</strong> semi-d.warfs relative to ta1l genotypes,
suggest modifícations <strong>of</strong> breeding procedures may be
required 1n attempting to inprove and adapt semi-dwarfs by
hybridizíng them with better performing taller genotypes
available. fhe low incídence <strong>of</strong> true semi_d.warfs indícated
a need for large F, poÞulations, perferably at lower <strong>plant</strong>
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