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Results and
Discussion
The plant height, seed weight, coleoptile length, root number and
maximum root length of parental lines and their mutants have been
presented in Table
1. All the
mutants were significantly shorter in plant height than their
respective parents. The maximum reduction in plant height compared to
parental line was recorded in M-19 (65.5cm) of wheat variety NI 5439
(106.3cm). Reduction in plant height of mutants was associated with
the reduction in seed size in all the mutants except three, M-53,
M-256, and M-257 of wheat variety K 65.
Seven mutant lines showed significant reduction in coleoptile length
as compared to parental lines. Three mutants, M-10 of wheat variety C
306, M-53 of wheat variety K 65 and M-252 of wheat variety NI 5439,
did not show any significant difference in coleoptile length as
compared to respective parental lines.
The embryonic root number in 7 days old seedlings of seven mutant
lines reduced significantly as compared to the parental lines. In the
rest three mutant lines, M-53 and M-256 of wheat variety K 65 and
M-250 of wheat variety NI 5439, there was significant increase in the
root number as compared to parental lines.
The root length of four mutant lines significantly decreased than the
parent varieties. Mutant 250 of wheat variety NI 5439 showed
significant increase in root length as compared to the parent
variety. In the rest five mutant lines the root length remained
unaffected.
All the three attributes of rainfed wheats i.e. coleoptile length,
root length and root number were combined in only one mutant (M53)
which did not show any reduction in grain weight also. Two mutants
(M-10 and M-252) showed long coleoptile (more than 6cm) as well as
seminal roots (more than 13cm) but this increase was associated with
the reduction in root number. Mutant 250 had increased root number as
well as root length but with reduced coleoptile length. Mutant 306
had increased root number only, the coleoptile as well as root length
were significantly reduced. In rest of the five mutants the reduction
in plant height was associated with the reduction in coleoptile and
root number and also with root length in M-56, M-257 and M-253.
Yadav and Sharma (1982) reported a positive association of embryonic
root number with root length and suggested selection for root length
on the basis of root number. In the present study no such association
was apparent since mutant 252 showed increased root length with
decreased root number and mutant 256 had decreased root length with
increased root number.
The faster early growth measured in terms of long coleoptile which is
an essential requirement for varieties under rainfed conditions. The
study indicated that in spite of a positive correlation between the
length of coleoptile and plant height it is possible to select fines
having long coleoptile with semi-dwarf plant stature. The study also
indicated that embryonic root length is not associated with root
number. Such studies may help in selecting suitable genotypes for
rainfed conditions. It is also evident from the study that the
coleoptile length is not under pleiotropic control of dwarfing genes
as reported by Woo and Konzak (1969).
References
Allan RE, Vogel DA, Surleigh JR and Peterson JrCJ (1961)
Inheritance of coleoptile length and its association with culm length
in four winter wheat crosses. Crop Sci 1: 328-332.
Anonymous (1976) International Rules for Seed Testing. Seed Sci &
Techno 4: 120.
Rajendra Kumar (1984) Induced mutagenesis for rust resistant in
wheat. Ph. D. Thesis, IARI, New Delhi-110012.
Rozentreter NA (1950) The importance of root system in wheat breeding
(Russian). Plant Breed Abstr 1951 21: 883.
Vedrob NG (1971) Questions concerning the breeding of wheat for
resistance to spring and summer draught (Russian). Plant Breed Abstr
43 (ii): 8619.
Woo SC and Konzak CF (1969) Genetic analysis of short culm mutants by
EMS in Triticum aestivum. Induced Mutations in Plants. Vianna
IAEA 551-555.
Yadav SP and Sharma SP (1982) A comparative study of seedling
characters in wheat, barley, Triticale and rye. Seed Research 10: 91-
97.
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