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

Íright be <strong>of</strong> great signifi.cance in row-spacing effects, and
research has been carried out on row-spacíng by genotype
interaction for yield involving genotypes differing in
ptant <strong>height</strong>. l'/orking with rice, Owen (1968) reported that
a semi-dwarf variety responded to narrow row spacing with
greater yields whiLe a tall cultivar did noì;. Stickler and
Younis (L966) report a similar result with sorghum.
Stoskopf (l-96?) reported no signíficant interaction in a
wheat study, but ihere was a trend for the short-strawed
high-yielders to yiel-d nore at narrow spacings.
Finlay et al. (tgZt) in their barley work, noted that
the higher yielding cultivars dísplayed a greater response
to narrower row spacing than did. the lower yielder:s.
The effects <strong>of</strong> row spacing on yieJ-d components have
been investigated. Decreased row spac ing has been reported
to give more spikes per unit area in barley (lttiddleton g! a1.,
1964i Finlay et al., I97I¡ Àhmed, I9?O), and more panicles
per unit area in oats (Foth et al., L964) and in rice (0wen,
1968). Narrower rows have been reported to decrease the
number <strong>of</strong> kernels per Èpike or panicle (Owen, 1968; Fintay
et al. , a97I) while Foth et aI. (f964), Middteton g!. af.,
(L964), and Csefalvai (1968) reported an increase as row
spacing decreased. îhe above authors reported little, if
any, effect <strong>of</strong> inter-row width on kernel weight.
Finlay et a1., (1971) reported earlier heading <strong>of</strong> bar-
l-ey at narrow row spacings in one <strong>of</strong> two yearsr Bríggs
(197 5) reported a trend toward earlier maturity in wheat at
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