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