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Molecular Plant Breeding 2013, Vol.5, No.7, 36
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37
1 Results
Distribution pattern of 5+10 and 2+12 Assortment on
the basis glutenin subunits at
Glu Di
locus revealed
that 5+10 dominated in the most congenial wheat
growth region of the country i.e. NWPZ (78%) and its
frequency dropped down to just 18% in harsh
environment of CZ (Figure 1). In NEPZ, where
growth conditions are not as favourable as that of
NWPZ, proportion of these two types was around
fifty-fifty. In the zone where environment was harsh
due to cold stress i.e. NHZ, 5+10 proportion dropped
to 37%. In PZ also, only 37% material showed 5+10
banding pattern. It clearly demonstrates that when
environment becomes harsh, proportion of 2+12
increases whereas under soothing growth conditions,
5+10 types are more successful. If two zones falling in
the Indo-Gangetic Plains (ME1 region as per
CIMMYT classification) are compared, NEPZ has
harsher environment in comparison to NWPZ, and the
proportion of 2+12 type wheats in that zone is also
larger (51% in comparison to 21% of NWPZ).
Similarly within the central-peninsular India, PZ
climate is more congenial in comparison to harsh CZ,
correspondingly 5+10 types increased from 18 to 37%.
Figure 1 Frequency distribution of
Glu D1
locus in different
environments
In AICW&BIP, there are two trial series i.e. timely
sown and late sown. The late sown materials face
more heat stress as temperature is relatively higher
especially during grain ripening. When timely sown
and late sown entries were sorted zone-wise to
observe heat influence within a zone, it was noted that
in timely sown condition of NWPZ, 95% material
belonged to 5+10 group only (60 entries out of 63) but
under late sowing; this proportion dropped to 64%. It
shows that even under wheat favouring productive
land of the country, proportion of 5+10 among the
high yielders decline when crop is cultivated under
heat stress conditions. Trend was same in each zone as
frequency of 5+10 declined in short duration wheats
of late sowing as the reduction was 70 to 23% in
NEPZ, 64 to 5% in NHZ, 30 to 11% in CZ and 39 to
35% in PZ. It clearly illustrates that irrespective of
agro-climatic conditions, frequency of 2+12 type’s
increases when wheat is grown under heat stressed
condition.
1.1 Difference in grain quality
Material under study had good number of 5+10 (260)
and 2+12 (298) entries. When grain and product
quality of two groups was compared, 5+10 had clear
edge over 2+12 in bread loaf volume and bread
quality score but no difference could be noticed
quality of
chapati
and cookies (Table 1). Sedimentation
volume, wet gluten content, gluten index, grain
hardness index and Glu 1 score had been rated high
among quality determinant of Indian wheats (Mohan
and Gupta, 2013a) and the 5+10 group expressed
significant advantage over 2+12 for all such attributes.
Grain hardness index was reduced in 2+12 wheats
because genotypes of grain hardness ≤50 could only
be observed in this category. Indian wheats
characteristically lack in soft grain texture and the
study material had only eight genotypes with grain
hardness index ≤50 and they all belonged to 2+12
group. Differences between two wheat groups were
insignificant in grain weight, grain protein percentage,
dry gluten content and flour extraction rate. Even
though confounding effect of regional and crop season
variations cannot be separated in this comparison,
differences were too glaring (
P≤0.001
) to ignore and
can be rated as characteristic features of two different
category wheats.
It was noticed that bread quality in 2+12 wheats was
lower because genotypes of loaf volume ≤475 cc and
bread quality score ≤5 could be noticed only in this
group, otherwise genotypes of good loaf volume
(≥600 cc) and quality score (≥8.5) were equally
available. Genotypes of good
chapati
score (≥8) could
also be noted in both categories. Even though overall
mean of biscuit spread factor was matching,
genotypes for good cookies (spread factor ≥10) could
only be noted in 2+12 wheats as soft grains desired for
good biscuit making were available in such materials
only. It shows that genotypes of good end-product
quality (except cookies) can be noted in both categories
of wheat. It was interesting to note that genotypes