| Results and Discussion The characteristics of the mutants isolated in the present studies are as follows: (i) Needle leaves - mutant plants are characterised by the leaves modified into needle like structures, either partially or fully; mutant plants are identifiable 45 days after germination (Fig. 1). (ii) Narrow leaves - the width of the leaves is reduced (1 - 1.5 cm) relatively to control (3.5 - 5.5 cm); leaves are errect (Fig. 2). (iii) Leaf tip plant - the leaves of the mutant plants are characterised by round apex, as against acute apex in control. These plants are 10 - 20 cm shorter than control/heterozygotes (Fig. 3). (iv) Waxless leaves - the mutant plant leaves are olive green colour (light green), smooth surface (due to absence of waxy coating) and slightly coiled; plants are dwarf (Fig. 4). (v) Twisting of flag leaf - the flag leaves of mutant plants at muturity were spirally coiled, the leaf sheath being malformed. (vi) White striped leaves - the mutant plant leaves characterised by the presence of irregular white patches (due to lack of chlorophyll pigment) and plants can be identified at any time from seedling stage to maturity of the plant. Segregation pattern and breeding behaviour of the mutants were studied in M2 , M3 and later generations. Out of six morphological mutants isolated for leaf character in each of the four hexaploid triticale varieties (Bagle, Coorong, TL 419, Welsh), except twisting of flag leaf the remaining mutants were found to be monogenically controlled with recessive inheritance. The Chi-square test for these five mutants gave a good fit to 3 : 1 ratio within M2 and M3 segregating rows (Probability ranging from 0.7 to 0.9) and a good fit to 1:2:1 ratio among M3 rows. While the mutant twisting of flag leaf segregated into mutant and normal without any definite pattern suggest that perhaps chromosomal disorders are involved. High frequency of mutants for leaf character relative to other morphological mutants (GRZESIK 1980, REDDY 1985) indicates that the genes responsible for these characters are more sensitive and readily available for mutagenic action of both gamma rays and EMS. High frequency of these mutants (REDDY 1985) in EMS treatments over gamma rays also supports that EMS causes more point mutations (GAUL 1964). References GAUL, H. (1964). Rad. Bot 4: 155-232 GRZESIK, H. (1980). Hod. Rosl, Akli. I Nasie. 24: 593-600 REDDY, V.R.K. (1985). Ph.D. Thesis, Meerut University, Meerut, India. |
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