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Triticeae Genomics and Genetics 2014, Vol.5, No.2, 1-11
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7
and depth of the seeds, a template was used. Two
seeds were dibbled per hole and after germination one
healthy seedling was retained at each hole after
thinning. All standard agronomic practices i.e., hoeing,
weeding and irrigation etc. were adopted uniformly.
For data collection ten guarded plants for each parent
and cross were tagged at random for each replication
in both regimes and data were recorded for plant
height of each of ten randomly selected plants from
base of plant to the tip of spike excluding awns of
mother shoot. At maturity the peduncle length of
mother shoot of the selected plant was measured from
last node (bearing the flag leaf) to the base of spike.
Similarly,
tillers number of each selected plant was
counted at maturity in each replication and average
was computed. The grains from ten randomly selected
plants in each replication of every genotype were
bulked separately. 100-grains were counted
randomly from each bulk and weighed on electric
balance (Compax- Cx-600). For grain yield all spikes
of individual selected plants were threshed manually
and weighed using electric balance (Compax-
Cx-600). The collected data were analyzed to
determine significant varietal differences among the
42 genotypes under both regimes following Steel
et al
.
(1997).
3.1 Heterosis and heterobeltiosis
The percent increase (+) or decrease (-) of F
1
cross
over mid parent as well as better parent was calculated
to observe heterotic effects for all the parameters. The
estimates of heterosis over the mid parent and better
parent (heterobeltiosis) were calculated using the
procedure of Matzingar
et al
. (1962).
Heterosis (%) =
Heterobeltiosis (%) =
Where,
MP = mid parental value of the particular F
1
cross (P
1
+ P
2
) / 2,
BP = better parent value in the particular F
1
cross.
Difference of F
1
mean from the respective mid parent
and better parent value was evaluated by using a t-test
according to Wynne et al. (1970).
t =
Where,
F
1ij
= the mean of the ij
th
F
1
cross,
MP
ij
= mid parent value of the ij
th
cross, and
σ
2
e
= estimate of error variance
Contribution of each author
Dr. Jehanzeb Farooq is the author of the article and
contributed in bulk of the work including write up and
analysis of the data. This research is the part of the
PhD thesis of Dr. Jehanzeb Farooq. Dr Ihsan Khaliq
contributed in the review of the current manuscript as
he is also the supervisor of the research conducted by
Dr. Jehanzeb Farooq.
Conclusion
Wheat production in Pakistan is better than before, but
terminal heat stress is still an alarming threat that
significantly reduces yield. The inferences obtained
from this experiment would be helpful to study the
performance and relationship of F
1
hybrids and
parents and to select suitable parents and population
for scheming effective wheat breeding regarding
thermal stress tolerance in wheat.
References
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100
MP
MP) - (F1
100
MP
MP) - (F1
σ2e 83/
MPij
- F1ij