Agriculture Reference
In-Depth Information
or plant yield) is likely to give the better response to
equivalent selection intensities, and why? Consis-
tently higher average values of
h
n
were obtained
at the farm near Boise. Which site, if either, is
likely to provide the most accurate estimate of
h
n
,
and why? Some of the heritability estimates (par-
ticularly those for plant height for 95.BAR.69 in
Moscow) varied greatly over the 3 year period.
What could be the cause?
(14) 4000 F
3
lentil breeding lines were evaluated for
yield and the highest yielding 500 genotypes
selected. The average yield of the 500 selection was
1429 kg/ha while the average yield of the discard
genotypes was 1204 kg/ha. A random sample from
the discards and the 500 selected lines were grown
in a properly designed F
4
trial where the average
yield of the random genotypes was 1199 kg/ha and
the yield of the selected 500 lines was 1362 kg/ha.
Determine the narrow-sense heritability for yield
at the F
3
in lentil.
(15) In a high diastase barley breeding programme it
is known that the correlation between yield and
diastatic power is
r
= 0.60. In this breeding pro-
gramme 3000 doubled haploids are evaluated for
yield and diastatic power in a properly designed
field trial. If you wish to retain approximately the
'best' 150 lines what proportion would your dis-
card based on yield and what proportion would
you discard based on diastase to achieve this
selected number.
(16) In 1998, 10 000 F
3
head-rows were grown in
an unreplicated, but randomized, design from
Bobby Z's Wheat Breeding Program
. At harvest,
seed from all rows were thrashed and weighed.
The average yield of all 10000 lines was found to
be 164.24 kg. After weighing, 200 rows were taken
at random and retained irrespective of their yield
performance. From the remaining lines the 'best'
1000 rows were selected for further evaluation in
the breeding scheme. The average yield of these
selected lines was of course higher than the whole
population at 193.74 kg. In 1999, the bulk F
4
seed
from the 200 random lines and the 1000 selected
lines were grown in a randomized complete block
design. At harvest, each plot was harvested sepa-
rately and the yield recorded. From this 1995 trial
it was found that the average yield of the selected
lines was 168.11 kg, while the average yield of the
200 randomly chosen lines was 133.41 kg. Deter-
mine the narrow-sense heritability for yield using
the above information. Explain how this value of
heritability found might influence your selection
strategy at future F
3
head-row selection stages.
(17) In a Douglas fir breeding programme you have
only sufficient resources to screen segregants from
two cross each year. However, in 1995, you have
been provided data of family mean (MEAN),
phenotypic variance (VAR), and narrow-sense
heritability (
h
2
from six crosses. From these three
statistics determine which two crosses you will put
your efforts in 1995 assuming that you will select
at only the 10% level, and explain, briefly, your
choices.
)
h
2
Cross code
MEAN
VAR
DF.33.111
22.3
16.7
0.45
DF.66.123
24.6
14.3
0.51
DF.97.37
28.1
6.3
0.47
DF.97.332
26.1
15.3
0.11
DF.99.1
22.5
10.2
0.84
DF.99.131
18.9
26.1
0.75
(18) 25 progeny from ten winter wheat crosses were
evaluated for yield in a properly designed F
3
cross
prediction study under field conditions. From the
results the following cross means and additive
genetic standard deviations (
σ
A
) for seed yields
were obtained:
Mean
σ
A
92.WW.46
236.60
127.34
92.WW.53
199.33
191.40
92.WW.54
241.82
91.43
92.WW.61
142.00
119.10
92.WW.71
133.11
125.46
92.WW.74
236.73
102.14
92.WW.93
233.55
281.77
92.WW.108
201.22
106.63
92.WW.111
229.37
299.39
92.WW.116
169.11
119.32
