| The emergence of the ear from such leaves that consisted of only blade
without sheaths was not regular. Internodes of the spikes were found to
be convoluted or spiral. This type of anomaly resulting into irregular shooting
can be ascribcd to the mechanical push of the ear that got arrested by the
auricles. Such type of irregular emergence has also been reported by MATSUMURA
(1955). Twin ear type chimera has been reviewed by several workers. MAC
KEY (1954) and KARAPETJAN (1960) believe that it is a recessive mutant whereas
SWAMINATHAN et al (1966) selected progenies of branched ear variants
from S35 culture and MASUBUCHI (1964) obtained branched
ears from a cross between Mantimus Amber x Red Genealogical. He classified
them according to the form and size of branching. He further remarked that
the aberrant characters were found to be cummulative and heritable. The appearance of solid internodes, on the upper region of the culm, signifies the potentialities of radiation in unravelling certain fundamental principles of evolution and cell lineages or organogenesis in wheat through mutagenesis. Other workers who have reported solid culms in their experiments are MAC KEY (1954). SCARASCIA et al. (1961) and AVANZI (1961). As per LARSON (1952) and SEARS (1956) at least some of the eleven chromosomes bearing genes for solidness might have been disturbed through irradiation. The character being monofactorial and dominant, it may be deduced that epistatic genes have been deleted from their loci (PLATT 1961). Supernumerary spikelets have also been reported oftentimes, as observed during the present studies (MAC KEY, 1954; SEARS, 1946; KARAPETJAN, 1960; BHATIA and SWAMINATHAN, 1963). MAC KEY believes that they are non heritable recessive. The degree of expression depends, to a large extent on the environment. Chimerical awning, which is of rare occurrence has been recorded by the author in Kenya Hunter - an awnless variety. Awndness has been established, through genetic studies to be a dominant character. These studies would tend to put forth that Kenya Hunter is an awned variety, the expression being inhibited by suppressor genes whose loci were deleted, while the expression of the various lengths viz. short typed (29.30%), long typed (13.37%) half awned (3.23%) and all other similar expressions, may be ascribed to the reduction or enhancement of dosage level of promotor genes. Literature Cited AVANZI, S. 1961. Atti Assoc. Genet., Italy 6: 353-64. BHATIA, C.R. and M.S. SWAMINATHAN 1963. Genetica 34: 58-65. D'AMATO, F., G.T. SCARASCIA, L.M. and A. BOZZINI 1962. Radiation Botany 2: 217-239. GAUL, H. 1963. Proc. XI Int. Cong. Genet. The Hague, Netherlands: 609-709. GAUL, H. 1965 Induction of mutation and the mutation process, Germany : 1-11. GUSTAFSSON, A., 1963. Recent Plant Br. Res. 89-104. KARAPETJAN, V.K., 1960. Agrobiology, 1: 82-85. MAC KEY, J. 1954. Hereditas, 40: 65-180 MAC KEY, J. 1960 Genetica Agraria 12 (3-4): 201-230. MATSUMURA, S. 1955. Seikenziho, Kihara Inst. Biol. Res. 7: 45-50. PLATT, A.W. 1961. IAEA Vienna 103-116. SCARASUA, G.T., F., D'AMATO, F. and A. BOZZINI 1961. Atti. Assoc. Genet. et al, 6: 371-80. SEARS E.R. 1956. Sonderdruck aus Handbuch der Pflanzenzuchtung. II. Band, 2. Aufl: 165-187 SWAMINATHAN M.S. 1964. Rep. FAO/IAEA Tech. Meet: 620-641. SWAMINATHAN M.S., V.L. CHOPRA and G.R.K. SASTRY. 1966. Ind. Agr. Res. Inst. New Delhi. TAVCAR, A., 1962. Arh. Poljopr. Nank. 15: 20-23. |
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