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

ship in common wheat. 0n the other hand, McNeal et al",
(f974) in studies using âdapted short strawed ând normal-
<strong>height</strong> wheats, reported a negative correlation as did
Rutger et al" (196?) in a barley study" Konlshi (f9?6)
indicated all the short types he studied had as many, or
slightl-y fewer, spikes than the normal strain.
ft should be noted that the number <strong>of</strong> heads per unit
area is much affected by the environment, as evidenced by
j.ts 1ow heritability estimates (Rutger g!, al. , 1966t Lebsock
and Amaya, L969), Since seeding rates can be easily rranip-
uLated to give variation in this eomponent, many workers
have acknowledged its inportance but hâve chosen not to
relate it to other characteristi"e s "
Kernels per spike ís the yield component with which the
seni-dwarf <strong>plant</strong> types have had the least problem; probably
since the material used to introduce the short culm was
selected wlth this in mind. Rasmusson (L9?3) noted that the
se:ni-dwarf mutant stock used in the Mínne sota barley program
had "normal spike length". syne (1972) indicated that the
seni-dwarf wheats had more kernels per spike than the talls,
as did Johnson et a1. (1966 (b)). syme (19?2) stated that
his studies in wheat indicated there was not necessarily a
direct associatlon <strong>of</strong> kernels per spike and <strong>plant</strong> <strong>height</strong>.
Other reports in wheat concur: Fonseca and Patterson (1968),
Lebsock and Amaya (1969). However, Barriga (L964) indicated
a positive relationship whereas the report by McNeal et aI.
(1974) showed a negative relationship between ptant <strong>height</strong>
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