Combining Ability Analysis for Seed Yield per Plant and its Contributing Traits in Castor (Ricinus communis L.)
Abstract
Aline × tester analysis of twenty four hybrids developed by crossing four lines and six testers were carried out under three diverse environments. The components of genetic variance were estimated from the analysis of variances for combining ability of different characters for each environment and pooled also. The analysis of variance for combining ability individual as well as pooled over environments revealed that mean squares due to lines and testers were significant for most the characters, Line × Tester was significant for all the characters except seed yield per plant and estimated genetic variance due to GCA and SCA was non-significant for all the characters in pooled over environments. The ratio of σ2gca/σ2sca was less than unity which revealed the predominant role of non-additive gene action for inheritance of the traits for days to flowering, days to maturity, number of nodes up to primary raceme, effective length of primary raceme, seed yield per plant and 100-seed weight. Therefore, heterosis breeding may be suggested to exploit hybrid vigour and recombinant inF and subsequent 2 generations for isolating lines for seed yield and its contributing traits. The line SKP 126 and tester SKI 420 were found as good general combiners for the yield attributing characters in pooled over the environments. Among the crosses, best three specific combiner were SKP 120 × SKI 420, SKP 126 × SKI 357 and SKP 106 × SKI 412 for seed yield per plant and its contributing traits.
Keywords
Download Options
Introduction
Castor (Ricinus communis L.), a monotypic species in the spurge family (Euphorbiaceae) with 2n = 20 chromosomes, is an important non-edible oilseed crop. India is one of the largest producers of non-edible oilseeds in the world. It is also known as the castor-oil plant, higuerito, higuerillo, palma, christi, carrapateira and many other common namesi.e. arindi, divela. In mature castor seed, 90-95% of the total seed protein is in the endosperm. In the endosperm, crystalloid proteins comprise 70 to 80% of the total protein and are insoluble in water. It has the approximate fatty acid composition of ricinoleic acid (87%), oleic acid (7%), linoleic acid (3%), palmitic acid (2%) and stearic acid (1%), with trace amounts of dihydroxystearic acid. Ricinoleic acid available in castor bean oil has its proven effectiveness in inhibiting the growth of various species of viruses, bacteria, yeasts and moulds. Ricin, a poisonous substance found in castor, is state-of-art tool in neurobiology for selectively destroying neuronal populations (De-La-Cruz et al., 1995).
The combining ability helps in partitioning the total genetic variation into general combining ability of parents and specific combining ability of crosses, which is useful to assess the nature and magnitude of gene action controlling different characters. The efficient partitioning of genetic variance into its components viz., additive and non-additive will help in formulating an effective and sound breeding programme. The cases where the cost of hybrid seed are of greater importance, the use of additive gene effects of parents could be used to retain the vigour in subsequent segregating generations to develop stable varieties, while non-additive gene effects respond to heterosis breeding. Among the several methods, Linex Tester analysis of combining ability is one of the important biometrical tools to identify the promising male and female parental lines as well as to obtain necessary data on the expression of heterosis for the future. Linex Tester analysis provides information for combining ability. The study of general combining ability (GCA) effects help in selection of superior parents and specific combining ability (SCA) effects for superior hybrids. With the help of this information it gives overall genetic pictures of the materials under investigation.
Conclusion
The estimates of genetic variance revealed preponderance of non-additive gene action for inheritance of days to flowering, days to maturity, number of nodes up to primary raceme, effective length of primary raceme, number of capsules on primary raceme, seed yield per plant and 100 seed weight. Therefore, population improvement by advancing hybrids involved in both good general combiner parents may be followed along with heterosis breeding; thus, superior recombinants may be isolated for future breeding programmes. The lines SKP 126 and tester SKI 420 were found as good general combiners for the yield-attributing characters in pooled over the environments. Therefore, these parents would be of immense value for the simultaneous improvement of desirable agronomical/morphological attributes in addition to heterosis breeding. Among the crosses, the best three specific combiner hybrids were SKP 120 × SKI 420, SKP 126 × SKI 357 and SKP 106 × SKI 412 for seed yield per plant. They also exhibited significant and desirable SCA effects for other component characters, justifying seed yield phenomena as a dependent complex character and is the outcome of direct and indirect effects of different component characters.
