| Peduncle length is predominantly controlled by polygenes and it is under
additive gene action (VlRK & AULAKH 1975). Longer peduncle is a dominant
character (CECCARELLI et al. 1973). Partial or complete dominance
of long peduncle has been indicated by the studies of HSU & WALTON (1970).
But in the present investigation partial dominance of shorter peduncle was
observed. BHAT & GOUD ( 1979) reported that the chromosomes i.e. 2A, 3A,
5A, 6A, 7A,1B, 2B, 4B, 5B, 6B, 5D, 6D and 7D increased the peduncle length.
In the present investigation, six critical lines 1A, 6A, 7A, 2B, 3B and
4B increased the peduncle length while the other three critical lines 5A,
5B and 6B decreased it (Table 1). From the present
investigation it is evident that, chromosomes 1A, 6A, 7A, 2B, 3B and 4B
in Bijaga Yellow carry genes inhibiting the peduncle length whereas chromosomes
5A, 5B and 6B carry promoter genes. Cytogenetic investigations of internode length are scanty. However, SHNAIDER & DOROKHOVA (1979) assigned the genes responsible for reduction in internode length on 1A, 3A, 4A, 5A, 6A, 1B, 2B, 3B, 7B, 1D and 3D in variety T13 and on 1A, 2A, 3A, 6A, 7A, 1B, 2B, 3B, 6B, 2D, 3D and 6D in variety Norona. In the present study, partial dominance for short internode length was observed. The two chromosomes i.e. 5A and 6B of Bijaga Yellow carried genes for first internode length and 6B alone reduced second internode length significantly whereas the critical lines for 1A, 2A, 3A, 3B and 4B for first internode and 1B, 2B, 3B and 4B for second internode increased the internode lengths (Table 1). Number of tillers per plant showed low heritability (NANDAPURI 1958, PANIGRAHI 1962, SELIM 1963). Partial dominance of low tillering ability over high tillering was found by SELIM (1963). In contrast to the above, CHAPMAN (1967), observed only additive gene action for tillering ability. The present investigation supports CHAPMAN'S (1967) results. Monopentaploid lines 1A, 2A, 3A, 5A, 3B, 4B and 6B were found to be critical for this character (Table 1). All these critical chromosomes had significantly lesser number of tillers. BHAT & GOUD (1979) reported the genes for decreased number of tillers to be located on chromosomes 2D and 3D and for increased number of tillers to be present on 7B and 6D chromosomes of UP 301. SEARS (1954) found nullisomics for chromosomes 2B and 3D having few tillers as compared to Chinese Spring disomic parent, which implied that these chromosomes had genes for increased tillering. Since Bijaga Yellow has more number of tillers, the decreased tiller numbers in seven monopentaploid populations involving the chromosomes of Bijaga Yellow may be attributed to hemizygous dominant nature of genes controlling the tiller numbers which in homozygous condition gave more tiller numbers. |
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