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Materials and methods
The experiment was laid out in a triplicated randomized complete
block design in split-plot fashion. Inqalab 91 and Pasban 90 are two
promising genetically diverse cultivars in Pakistan and are
cultivated in different zones. Inqalab 91 is a high yielding variety
well suited to irrigated conditions in comparison with Pasban 90.
These varieties were planted in main plots consisting of 10 rows of
five meter length with 25 cm spacings between rows. The varieties
under main plots were subjected to following treatments under
split-plots.
T1 = Control (Intact plants)
T2 = Flag leaf removed at heading (spike emergence)
T3 = 3rd nodal leaf removed at heading
T4 = Awns removed at heading
At spike emergence flag leaves of 10 randomly selected plants, 3rd
nodal leaves from other 10 plants and awns from another set of 10
plants were removed and plants were individually tagged. Similarly 10
intact plants were also tagged as control. Flag leaf and 3rd nodal
leaf area was measured according to Muller (1991). Observations on
spikelets per spike, seed set, grains per spike, grain weight per
spike and 100-grain weight were also recorded at maturity. Data
collected were subjected to analysis of variance according to Steel
and Torrie (1980) to sort out differences among treatments. Treatment
means were compared using Duncan's multiple range test as described
by Duncan (1955). Percent reduction for significantly affected traits
was also calculated in each of the treatment in comparison with
control.
Results and discussion
Varieties, in addition to other yield related traits, also
differed significantly for flag leaf and 3rd nodal leaf area
(Table 1). Mean flag leaf and 3rd nodal
leaf area was 19.53 and 23.78 cm2 in Pasban 90 and 26.20
and 34.32 cm2 in Inqalab 91, respectively, (Table
2).
A significant effect of the treatments (removal of green
photosynthetic parts) was observed for seed set percentage, grains
per spike, grain weight per spike and 100-grain weight (Table
1).
The results revealed a prominent overall reduction, 16.4% in seed
set, 14.8% in grains per spike, 34.5% in grain weight and 20.0% in
100-grain weight when flag leaf, the main photosynthetic organ, was
removed (Table 2).
Maximum seed set (70.0%) was obtained in intact plants and removal of
just a flag leaf reduced this value to minimum (66.8%). Removal of
other parts, i.e. awns and 3rd nodal leaf also reduced the seed set
significantly but their effect was not so much pronounced as that of
removal of flag leaf alone (Fig. 1a). Seed
set percentage is directly related to number of grains per spike thus
the similar trend was observed in case of grains per spike (Fig.
1b). When the flag leaf was removed, the number of grains reduced
to minimum (50.2) in comparison with the maximum (58.9) in intact
plants. Removal of 3rd nodal leaf or awns had also depicted a
significant impact on grain number per spike. Nevertheless, effect of
both of these treatments was statistically at par among themselves
for this trait.
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