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Materials and methods
The materials involved as parental lines in the development of
high yielding genotypes were local germplasm (SFW) and two released
wheats (Vaishali and Vidisha) with bold, lustrous grams and carrying
tightly linked resistance genes for leaf and stem rust from
Agropyron elongatum (Lr24/Sr24 ).
SFW has very long ear-heads with high spikelet number but unfilled
middle spikelets, long and shriveled grains, and fewer tillers per
plant and high susceptibility to rusts. This germplasm line has been
included as one of the parents in crossing program with a view to
filling all the spikelets with bolder grains and combining other
desirable traits from the second parent.
The other parents Vaishali and Vidisha which were crossed with the
local type are released cultivars for timely sown irrigated
conditions and late sown irrigated conditions in North Eastern Plains
Zone and Central Zone, respectively. These parents were chosen with
the objective to combine genes for resistance to stem and leaf rusts
and also to look for optimum combination of tillering habit, grain
weight and grain number in single genotype. Along with this material,
four varieties, namely, PBW343, HD2687, HD2329 and UP2338 were
included as checks in the present investigation for comparing yield
and yield yield components.
The new efficient plant type combining desirable yield components
along with resistance to stem and leaf rusts was developed through
modified pedigree method of selection from F2 to
F5 generations. Two crosses of SFW with Vaishali and
Vidisha were attempted and F1's were bulked. A very large
F2 population (approx. 2500 plants) of these two crosses
was planted. The spreader rows were planted all around and in
between, at regular interval. The artificial epiphytotic of leaf rust
was created by inoculating the spreader rows with the urediospores of
most virulent and prevalent pathotype 77-5 with the help of
hypodermal syringe. The selection in F2 generation was
exercised for plants combining optimum tillering, long and well
filled ear-heads and resistance to leaf rust. Selected F2
plants were individually harvested and screened for well-filled, bold
and lustrous grains; F3 families were raised from
F2 plants in 2.5 m x 2 rows plots. In selected
F3 families exhibiting resistance to rust and good
tillering, long and well filled ear-heads were picked up and threshed
individually. In F4 and F5 generations, ear row
progenies were planted in epiphytotic conditions of leaf rust, and
long, well-filled ear-heads were selected from the selected progeny
rows having desired plant type and grain selection was exercised. The
finally selected ear-heads from a progeny row were bulked and
evaluated in a yield trial comprising 6 rows of 5 m length with 3
replications evaluated in randomized block design during 1999-2000.
One square meter plot from the middle of the plot of each entry in
all replications was cut from the ground level when it is fully
matured. The data on biological weight, grain yield, number of
tillers were recorded from this one square meter plot area. The
number of grains per ear-head were calculated from randomly selected
50 ear-heads from the harvested plot. The data collected on various
traits were analyzed for variance (ANOVA) and correlation among these
traits.
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