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In NP 880 the rust reaction recorded for cheek was of 2
type, but the mutant line 3-25(3), 3-26(1) and 3-11(1)
showed '0' type reaction, thereby indicating better
resistance over the check. It was an interesting observation
that all the seven mutant lines which revealed better
resistance at seedling stage had originated from EMS
treatments (Table 2). This type of
specificity of EMS treatments for the manifestation of
mutants with better resistance is of great practical
importance. Some sort of specificity with EMS treatments
have been reported by FAVRET (1960) in barley and
SWAMINATHAN et al.(1962) in wheat.
Induction of specific type of mutations by EMS has been
attributed to its localized chromosomal effects where the
respective genes are presumably located. Mutant lines
conferring resistance to stem rust both at seedling and
adult plant stage have been isolated after NMU treatments in
Kharchia Local and Lal Bahadur bread wheat varieties
(SAWHNEY et al. 1979).
About fifty thousand of M2 plant population was
separately screened for tetraploid and hexaploid wheat
varieties to isolate, visible mutations pertaining to
alteraction in height, early maturity, and adult plant rust
resistance. Subsequently, fifty progenies emerging from
different treatments were selected on the basis of
M3 progeny performance. Emphasis for selecting
promising progenies was associated with desirable traits of
uniform maturity, compact spike length, erect leaf and
reduced mottling in kernels in M4 generation. In
this case, observations were confined to single plant yield,
100 kernel weight and protein percentage. Further screening
and selection in M4 and M5 ultimately
culminated in the recovery of sixteen promising mutant
lines, which showed variable yield potentials, better
resistance and some upgrading in protein percentage. Mutant
selection 246 showed yield of 40.3 q/ha against 26.9 q/ha
recorded in normal check HD 4502. Mutant lines also
exhibited better yield performance in comparison to parental
check. It was interesting to note that with the increase in
yield there was no corresponding decrease in grain yield.
For 100-seed weight there was substantial increase in mutant
line 314, 276 and 104-122. Protein content was not
significantly affected in mutant lines of durum wheat
but moderate increase in mutant selections 104-122, 246 and
268, was recorded. These mutant lines also depicted
significant increase in yield over the parental check HD
4502. It was thus evident that some of the negative linkages
have been broken and new mutant character association have
been formed in some mutant lines. Three mutant selections
from durum wheat viz., 104-122, 246 and 268 are
presently being evaluated at All India initial evaluation
trials.
Mutation breeding has also been used for the improvement of
grain quality. Higher percentage of protein without
affecting grain yield has been achieved in some mutant lines
of Lal Bahadur (SAWHNEY et al. 1978). Induced
variability for protein content in bread wheat was reported
by SINGH et al. (1979) where the protein range for
mutant line was 10.2 to 13.9 per cent as compared to 11.1
per cent in control. Some mutant lines with higher protein
content but reduced grain yield was reported by DESAI
(1979). Interestingly, the lines which gave higher protein
percentage in HD 4502 also gave higher yield than control
(Table 1). Yield and seed weight
are generally negatively correlated. However, in mutant
lines 276, 314 and 104-122 of HD 4502 have not only shown
substantial increase in yield but have revealed higher grain
weight. It is interesting that 104-122 alongwith increase in
yield (control 26.9, mutant 32.3 q/ha) and higher grain
weight (control 4.13, mutant 5.25 g/100 seeds) was coupled
with higher protein percentage.
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