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

given rise to increased ni-trogen in the grain, particularly
at higher level-s <strong>of</strong> applied nitrogen in barley (Reisenauer
and Dickson, 196I; Kírby, 1968; Gardener and Rathjen, 19?5),
and in wheat (Woodward, Ip66¡ Syne, 196? ¡ McNeaI g! ê1.,
19?t¡ Ðubetz, 1972 r Gardener and Jaekson, 1976; Syme et al.,
19?6), [he first increments <strong>of</strong> nitrogen fertilizer tend to
give larger yield increases with a small increase in grain
nítrogen content while further Íncreases <strong>of</strong> nitrogen tend
to give a reverse effect (Syme, L96?).
Pl-ant <strong>height</strong> increases with addition <strong>of</strong> nitrogen in
both tall and semi-dwarf varieties (Pendl-eton gq 41. , L953;
Rohde, 19ó3; Woodwarð,, I)66¡ McNeal et al., I9?I). However,
Chandler (tgøg) pointed out that in the nítrogen responsive
semi-dwarf rice varieties the internode elongation due to
nitrogen fertílizer is rel-ativel-y less than that in the
non-responsive tall types. Konishi (f9?6) indicated that
all genotypes he studied responded similarly for culm length
as fertilizer increased.
McNeal- and Davis (1954) and McNeal et al. (I9?I) report-
ed no effect <strong>of</strong> nitrogen application on test wei-ght in wheat,
while Rohde (1963), working at low rates <strong>of</strong> applied nitrogen,
reported an increase in test we ight as nitrogen level in-
creased.. Tn a barl-ey study, Reisenauer and Dickson (1960)
reported thât the fírst 40-pou¡d-per-acre increment <strong>of</strong>
nitrogen gave an increase in kernel plumpness, while the
next two 4o-pound increments resulted in decreased kernel
plunpness.
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