Agriculture Reference
In-Depth Information
standard error of the mean (s.e.)
are shown
that
the
expectation
of
your
test
should
be
below:
equal
to
zero
given
an
additive-dominance
model.
(13) A cross is made between two homozygous barley
parents. One parent is tall and resistant to mildew
(i.e. TTRR ) and the other parent is short and sus-
ceptible to mildew (i.e. ttrr ). Height and mildew
resistance are both qualitatively inherited with tall
being dominant to short, and resistant dominant
to susceptible. If the F 1 family from this cross
were self pollinated how many F 2 plants would
you need to grow to ensure a 99% certainty of
having at least one plant which was resistant to
mildew and short. Consider now the same cross
( TTRR
Mean
s.e.
P 1
244
2.00
F 1
217
2.41
B 1
232
3.64
Using an appropriate scaling test, determine
if an additive-dominance model is adequate to
describe the observed variation in this character.
When breeding field beans, it is very difficult to
obtain large numbers of F 1 seed. Therefore scaling
tests which include the F 1 or either backcross (B 1
of B 2 )
ttrr ) and in a breeding programme 6400
F 2 plants were evaluated. At harvest only the short
mildew resistant plants were selected and grown
as F 3 head rows (i.e. only these selected types were
evaluated at the F 3 stage). Determine the expected
number of genotypes and phenotypes you would
have when you harvest the F 3 rows.
×
is prohibitive. Design an appropriate scal-
ing test using the F 2 ,F 3 families and both parents
(P 1 and P 2 )
and using m ,
[
a
]
and
[
d
]
,
show
 
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