GENETICS OF RESISTANCE TO RENIFORM NEMATODE (Rotylenchulus reniforms), YIELD AND YIELD COMPONENTS IN CASTOR (Ricinus Communis L.)
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Date
1996
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AAU, Anand
Abstract
The study was conducted at Departments of Plant Breeding and Nematology, B.A. College of Agriculture, Gujarat Agricultural University, Anand Campus. Anand during kharif, 1995-96 involving eleven crosses viz., SPS 43-3 x 48-1, 48-1 X ARUNA, 48-1 x TMV 5, SPS 43-3 x SKI 49, VP 1_ x ARUNA, VP 1 X TMV 6, ARUNA x SKI 49, TMV 5 x SKI 12, SKI 12 X SKI 49, ARUNA x TMV 5 and ARUNA x SKI 12, each having six generations (P1, P2, F1, F2, B1 and B2) in a compact family block design replicated thrice for the estimation of genetic parameters (Gene action, Heterosis, Inbreeding depression, Heritability and Genetic advance) for resistance to reniform nematode, seed yield and yield components in castor (Ricinus communis L.). Scaling test (Hayman and Mather, 1955) was done to check the adequacy of the additive and dominance components Gene effects were estimated using six parameter model suggested by Hayman (1958) and three parameter model suggested by Jinks and Jones (1958). The analysis of variance revealed significant variation among different generations for all the characters except oil content in almost all crosses studied indicating considerable variability in the material tested. Higher magnitude of additive and non-additive gene effects in the expression of resistance to reniform nematode in hybrid combination SPS 43-3 x 48-1, and higher mean and significant heterosis (-41.42 %) and heterobeltiosis (-40.98 %) in desirable negative direction suggested that the isolation of homozygous recombinants having desirable level of resistance to reniform nematode from advance segregating generations would be feasible. For seed yield and its components (viz., length of main raceme, number of capsules on main raceme, number of total and effective branches/plant and 100 seed weight) two hybrids viz., ARUNA x SKI 12 and VP 1 x ARUNA expressed significant positive heterosis and heterobeltiosis. The cross, ARUNA x SKI 12 showed highest relative heterosis (58.96 %) and heterobeltiosis (53.20 %) with the maximum seed yield (269.44 g) per plant followed by hybrid VP 1 x ARUNA with 45.54 % relative heterosis, 21.94 % heterobeltiosis and 208.76 g seed yield/plant. Additive and non-additive gene effects largely involved in the expression of seed yield and its component characters suggested the feasibility of the exploitation of hybrid vigour on commercial scale or alternatively to follow cyclic method of breeding involving selection of superior recombinants and their inter se crossing for evolving desirable genotypes of castor. In general, the crosses showing significant heterosis and heterobeltiosis also exhibited significant inbreeding depression. Low magnitude of narrow sense heritability observed for resistance to reniform nematode, seed yield and yield components in almost all crosses studied revealed the importance of non-additive gene action in the expression of these traits. Moderate to high heritability coupled with moderate genetic advance as per cent of mean for seed yield and its components in various crosses suggested that seed yield and its components can be improved upon by following selection in succeeding generations. Low narrow sense heritability coupled with low genetic advance observed for oil content suggested slow improvement in this quality trait through selection.
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PLANT BREEDING AND GENETICS, AGRICULTURE, A STUDY