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

esults are in agreement rvith previous reports by Gu_itard
et a!, (196i") ¡ however, as has been the case in yei other
studíes (¡'i-nfay et a!. 1!lO and Woodward, 1956) t}re seedlng
rates used did not cover a wide enough range to give
significant differences at two <strong>of</strong> the sites. fhe result
at Carrnan, where seedj-ng was delayed, supportecl the r.eport
<strong>of</strong> Day and Thompson (l-97O) who found thaÈ as seeding was
delayed the seedång rate needed to be increased.
Row spacing affected yield at all sites (ta¡le 56).
fhe significant effect at all sites was due to lower yield
at tiìe widest row spacíng (fanfe 57¡" Similar results were
reported by Holliday (tg6l). The results (natfe 57¡
indicated no ad,¡antage <strong>of</strong> the narrowest row spacing
compared to the interroediate, contrary to the findings <strong>of</strong>
Holliday (tgSl). llowever, at Carma¡ n under ad.verse growing
conditions with heavy weed infestations, there was a trend
toward the narrov¡est spacing yielding rnore.
No significant first order interactions occu_rred
(lable -(6). $owever, the resuLts <strong>of</strong> Table 52 indicated a
trend towards the somÍ-dwarf being more responsive to seeding
rate increases, particularly under the near-optimal
condåtions at Winnipeg, in which the tall variety shorÀ'ed
a negative response to increased seeding rateo Such trends
wer€ reported by Si;icklez' and younis (Ig66) with sorghun
genotypes Ciffering in <strong>plant</strong> <strong>height</strong>" fhe genotype x row
spaeing rneans (Table 5?), fcr Carman, also showed a trend
to hígher seini-dwarf yield at the narrowest row spacing,
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