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Results and discussion
All the traits (grain yield/m2 number of tillers/m2, 1000-grain
weight and number of grains/ear) except biological yield were highly
significant which indicate very high variability in the material
under study.
Out of the nine newly developed lines, four lines yielded higher than
all checks including the most popular variety PBW343 in northern and
western parts of the country (Table 1). The
line DL1266-2 significantly out yielded the best check variety PBW343
and also both parental lines (SFW and Vaishali). This genotype is the
ideal genotype with respect to optimum combination of tillers
(335/m2), high grain weight (45. 6 g) and number of grains per ear
(46). This genotype also occupied first rank on mean yield per plot
basis. Breeding genotypes combining optimum tillers per plant and
higher yield contributing traits (grain weight and number of grains),
DL1266-2 is the most suitable example.
Another genotype DL1266-1 from the same cross also yielded higher
than all the four cheeks and parental lines. However, it ranked 8th
on the basis of grain yield per plot. This genotype has the best
combination of 1000-grain weight (51.5 g) and grains per ear (50) but
has low tillering habit. This type of genotype becomes the base
material for further improvement in tillering habit. DL1266-6 is the
third genotype of the same parentage, which is similar to DL1266-2 in
optimum combination of yield contributing traits.
The fourth genotype DL1280-1 from a cross between HD2329 and Vaishali
is also superior to all the check varieties. However, this genotype
has a different combination of yield contributing traits. It has the
highest number of tillers (611/m2 ) and also very high 1000-grain
weight (46.1 g) but less number of grains per ear (24). This genotype
ranked second on the basis of grain yield per plot.
DL1267-3 (SFW x Vidisha) that yielded on a par with the best check
(PBW 343) has optimum combination of all the three yield contributing
traits.
SFW has low tillering (304/m2) and low 1000-grain weight (33.3 g) and
moderate grains per par (40) but the number of spikelets per spike
were very high, though poorly filled. It has been observed that the
grains were very long but shriveled resulting in low grain weight.
The two parents Vaishali and Vidisha have higher tillers per plant
and high grain weight and low grain number per ear.
With the new strategy, DL1266-2, DL1266-1 and DL1266-6 (with common
parentage) have been developed with new plant type (Fig.
1) where in the physiological efficiency of partitioning of dry
matter to economic yield has increased. This increase in
physiological efficiency is due to increased availability of
photosynthate for proper filling of sink leading to very high grain
weight and proper filling of all the grains in all the spikelets
resulting in higher number of grains per ear. In fact, in SFW, the
number of spikelets/spike are very high but grain formation is low
because the poorly filled grains are highly shriveled and
unaccountable. The grains per ear in line DL1280-1, which do not have
SFW as one of the parents, are very low (24), further suggesting the
role of SFW in contributing to high grain number in newly developed
genotypes. It is generally observed by several workers (Gandhi et al.
1964; Bhatt 1973; Chaudhary et al. 1977; Sinha and Sharma 1979;
Balyan and Singh 1987; Pawar et al.1990) that two yield contributing
traits, grain weight and grain number per spike are negatively
correlated. It is also known that the increase in tiller number per
plant leads to decrease in grain weight and number of grains per ear.
However, the newly constituted plant type (in the form of DL1266-1,
DL1266-2 and DL1266-6) has shown increase both in grain weight and
grain number per ear with moderate tillerinig capacity (Fig.
2 and Fig. 3). The significant positive
correlation between grain weight and grains per ear is evident from
this study (Table 2).
It was also possible to successfully combine high tiller number and
high grain weight in a genotype DL1280-1, which are otherwise
negatively correlated components of yield.
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