Habilidad combinatoria de los caracteres relacionados con la producción de habichuela (Phaseolus vulgaris L.)

Las variedades de habichuela cultivadas en Colombia presentan un bajo potencial de producción, por lo que se hace necesario adelantar programas de mejoramiento, cuya ejecución depende del conocimiento de la habilidad combinatoria de los cultivares disponibles. Con el objetivo de evaluar la acción génica predominante en caracteres de importancia económica, se evaluaron 15 híbridos directos y seis progenitores. Las habilidades combinatorias general (HCG) y específica (HCE), se estimaron con el Método 2 modelo 1 de Griffing, que considera a los progenitores y sus cruzamientos directos. Se midieron los caracteres: número de vainas y producción por planta, peso promedio y longitud de la vaina. Los resultados indicaron efectos genéticos aditivos para longitud de la vaina; por el contrario, el número de vainas y producción por planta, se vieron influenciados por efectos genéticos no aditivos, mientras que el peso promedio de la vaina fue controlado por efectos genéticos, tanto aditivos como no aditivos. Los progenitores 1 y 6 mostraron efectos positivos más altos de HCG, para el peso promedio y longitud de la vaina, mientras los progenitores 5 y 6, lo fueron para la producción de vainas por planta y los progenitores 4 y 5, para el número de vainas por planta. La estimación de HCE más alta para todos los caracteres, se presentó en el hibrido 1x2, siendo la más adecuada para mejorar la producción de la habichuela.

Green bean varieties grown in Colombia have low production potential, therefore it is necessary to carry out plant breeding programs, which execution depends on the knowledge of the combinatorial ability of the available cultivars. To evaluate the predominant gene action in economically important traits 15 direct hybrids and six parents were evaluated. General combining ability (GCA) and specific combining ability (SCA) were estimated with Griffing's Method 2 model 1, which considers parents and their direct crosses. The characters: number of pods and yield per plant, average weight and pod length were measured. The results indicated additive genetic effects for pod length. In contrast, pod number and yield per plant were influenced by non-additive genetic effects, while average pod weight was controlled by both additive and non-additive genetic effects. Parents 1 and 6 showed higher positive effects of HCG for average pod weight and pod length, while parents 5 and 6 for pod yield per plant and parents 4 and 5 for number of pods per plant. The highest ECGH estimation for all traits was found in the 1x2 hybrid, being the most suitable for improving bean production.

Genetic control of reproductive and fruit quality traits in crosses involving cultivars and induced mutants of tomato (Solanum lycopersicum L.)

Development of mutants and their effective utilization to incorporate desirable traits in tomato would be a sound improvement strategy to develop so called ‘smart’ tomato variety of the coming century. Initially we developed three induced mutants from two varieties, ‘Patharkuchi’, a local adapted cultivar and an introduced variety ‘Berika’, and then three crosses (Berika 9 P Mut-5, Berika 9 P Mut-11, Patharkuchi 9 B Mut-1) were made to involve in these two varieties and their respective mutants. Six generations (P1, P2, F1, F2, BC1 and BC2) of three crosses were utilized to study the genetic control of yield and quality traits, and to study the genetic basis of formation of dark green fruit. The nature and magnitude of gene action controlling the inheritance of 27 quantitative traits differed from one cross to another and from one trait to another, mostly conditioned by nonadditive gene action and duplicate epistasis. The prevalence of duplicate epistasis in three crosses for most of the traits revealed that the pace of progress through conventional selection process would be hindered as this kind of epistasis might result in decreased variation in F2 and subsequent generations. Recurrent selection in biparental progenies would be helpful for exploiting this type of nonallelic interaction through generation of high frequency of desirable recombination and concentration of genes having cumulative effects in the population. We also observed complex genetic behaviour of some of the traits revealing significant epistatic components. Inheritance study of ‘dark green fruit’ (dg1) of Berika 9 P Mut-5 cross revealed a single recessive gene governing the trait and expressed when the mutant gene was in homozygous recessive condition (designated as dg-1/dg-1).

Determination of gene action for yield and its related traits in soybean under North-Western Himalayas conditions of India

Aim: To understand the nature and magnitude of gene action for yield and its related traits in soybean.Methodology: Fifty four triple test cross progenies developed by crossing 18 lines with three testers Him soya and Hara soya (P1 and P2) and their F1s were used as testers ‘L1’,’L2’ and ‘L3’. F1 seeds were produced by crossing Him soya with Hara soya during kharif 2011. By crossing these three testers with 18 lines (females), 54 triple test cross hybrids were developed during kharif 2012. The fifty four F1 hybrids along with 18 lines and 3 testers were sown during kharif 2013 in a randomized block design with three replications. Results: In the triple test cross progenies, sufficient genetic variations were found for all the traits, except petiole length. Epistasis was observed to be an integral part of genetic variations for traits like plant height, branches per plant, nodes on main stem, internode length, pods per plant, pod length, biological yield per plant, seed yield per plant, oil content, crude protein content. Epistatic interaction for most traits was additive x dominance and dominance x dominance (j+l) type. In addition to additive x dominance and dominance x dominance (j+l), additive x additive (i) type epistasis was observed for plant height, internode length, pods per plant and biological yield per plant. For the inheritance of most traits, fixable type of gene action was found as additive component (D), was more pronounced than dominance component (H), except pod length. Interpretation: For improvement of traits, selection in the early generations will be useful as additive gene action was observed. The importance of additive x dominance (j) and dominance x dominance (l) type of epistasis in the inheritance of seed yield and other related traits signifying the importance of recurrent selection in order to develop high yielding varieties. For pod length, both additive and dominant components were observed. Thus genetic improvement in seed yield would be easier through indirect selection for pod length.

Assessment of various genetic components through NCD-I and NCD-III designs of biparental mating in opium poppy

Creation of genetic variability and development of varieties having higher yield potential depends on information about nature of gene action. The present investigation was undertaken to decipher the nature of gene action and allied genetic parameters involved in the inheritance of yield and yield-related component traits in opium poppy (Papaver somniferum L.). The biparental inbreeding progenies derived from four segregating base populations of crosses NB-1Kr40-3/3×NB-1Kr30+0.2-2/1, NB-5Kr40-7/2×58/1, NB-1Kr30+0.2-2/1×58/1 and NB-Kr40-3/3×NB-5Kr40-7/2 of opium poppy were analysed to study the gene actions involved in the inheritance of yield and component traits. Additive component of variance played a predominant role in North Carolina design (NCD)-I, while both additive and dominance genetic components were found important in NCD-III design. The presence of additive as well as nonadditive components of variance suggested that one or two generations of intermating in further generations followed by selection may lead to development of novel genotypes.