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

showed no environmental interaction in C_?O_Z, However, in
C-70-1 and C-?O-3 heritabilities were low and subject to
l-arge standard errors¡ in C-fo-I the low level <strong>of</strong>{ corn_
bined with the large øfr" *as primarily responsible. A very
-)
rargeO¡õy was the culpr5.t in C-IO-J, This again pointed to
the effects <strong>of</strong> stress on C_IO_J; a similarly high genotype
by year interaction was found in that cross for days to
heading. Ln I9Z4 C-?O-j headed earlier and had fewer kernel"s
per spike than in IgZ3,
the significant levels <strong>of</strong>Aåf in C_lo_2 and C-?o_j
indicated that testing for kernels per spike required more
than one year <strong>of</strong> data, while the lack <strong>of</strong> significant levels
,
o¡Ofrf, suggested that one locatlon was sufficient. The un-
desirably farge Oi! may have resuLted from Lack <strong>of</strong> adequate
repll-cation, sanplÍng size, or a combination <strong>of</strong> these.
Tield. Genotype by environment interaction has <strong>of</strong>ten
been implicated in difficulties in differentiatl_ng among
yield 1eve1s in various crops. Neverthel-ess, the results
<strong>of</strong> the present study tended to agree with those <strong>of</strong> Rasmusson
and class (L96?). In all three popuJ.ations the error
t
component Ç) <strong>of</strong> variance was larger than the genotype by
environnent interaction components, suggestÍng that nore
replication and/or rârger ptot size would have beer¡ a rnore
efficient way to increase the heritabílity <strong>of</strong> yield than the
utilization <strong>of</strong> more locations and./or years <strong>of</strong> testing. fhis
was parti.eularly the case in C-?0_j..
Heritability was relatively hlgh (58 + 14.0) ana6f""
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