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Bt Research 2013, Vol.4 No.5 24-28
ISSN 1925-1939
http://bt.sophiapublisher.com
26
With Bt in genetic background, it is mandatory to
enhanced the total photosynthetic output of the plant
so that the plant can meet the demand of enhanced
harvest index. Traits such as higher photosynthetic
ability, higher leaf area, stay green nature, etc become
very important in overcoming this Bt induced
mismatch between source and sink. These traits first
need to be incorporated in the parental genotypes so
that they can be released as varieties and additionally
they become good source for developing hybrids.
The objectives of the present study were: Bt gene
produces poisonous protein to kill bollworm. Is it
causing any other effect on the plant? Is the increased
sink’s capacity realized? What is the impact of this on
the Source? Is the plant phenology capable of
sustaining enhanced sink?
This research work was aimed at seeking answer to
these questions.
1 Results and Discussion
1.1 Productivity features of Bt cotton hybrids
The data on 15 hybrids developed through crossing
were subjected to statistical analysis. The results
revealed that among the entries tested, the hybrid 1
has registered the highest yield of 4726 kg/ha, this
reflects that the harvest index of upper half and lower
half same 0.32, 0.31 respectively, this hybrid came
from a good crossing. The same result was found in
hybrids 2,3,4,5,6,7,8,9,10 and 11. On the other hand,
the hybrid 15 showed the lowest yield of 3106 ha/kg
that means the harvest index in lower half (0.28) is
more than upper half (0.21) and this hybrid came from
a bad crossing. The same result was found in hybrids
12, 13 and 14 that recorded lower yield and
differences between lower half and upper half that
mean these hybrids came from bad crossing. From
those data we can see that many of the less productive
Bt hybrids revealed higher productivity in the lower
half than the upper half, the harvest index was higher
in the lower half as compared to upper half (Table 1).
It can be inferred that Bt gene induces enhanced sink
and in some of these less productive hybrids the
vegetative growth can not match the demand of
enhanced sink thereby leading to lower yield coupled
with leaf reddening and early senescence.
Table 1 Productivity features of Bt cotton hybrids
No. of entries: 15 harvest index yield (kg/ha)
Harvest index
Yield (kg/ha)
Entry name
Boll number
Boll weight (g)
LH
UH
LH
UH
Total yield (kg/ha)
Hybrid 1
31.5
4.9
0.31
0.32
2458
2269
4726
Hybrid 2
41.0
6.1
0.31
0.32
2385
2202
4587
Hybrid 3
33.0
5.1
0.32
0.31
2303
2213
4517
Hybrid 4
34.5
5.1
0.32
0.31
2299
2209
4507
Hybrid 5
31.5
4.9
0.31
0.31
2236
2191 4427
Hybrid 6
42.3
6.2
0.32
0.31
2175
2131
4306
Hybrid 7
37.2
5.6
0.29
0.28
2110
2196
4305
Hybrid 8
35.7
5.4
0.33
0.32
2147
2147
4294
Hybrid 9
39.7
5.9
0.29
0.23
2684
1510
4194
Hybrid 10
30.8
4.3
0.29
0.23
2628
1478
4106
Hybrid 11
46.5
6.8
0.31
0.23
2522
1545
4067
Hybrid 12
37.3
5.6
0.32
0.25
2474
1516
3990
Hybrid 13
44.7
6.6
0.32
0.25
2403
1537
3940
Hybrid 14
35.5
5.2
0.28
0.21
2154
1377
3530
Hybrid 15
33.5
5.2
0.28
0.21
2081
1025
3106