Quantitative genetic studies in flue-cured tobacco (Nicotiana tabacum L.). II. Certain physical and chemical characters

Abstract

PANDEYA, R. S., V. A. DIRKS, G. POUSHINSKY, and B. F. ZILKEY. 1985. Quantitative genetic studies in flue-cured tobacco (Nicorionn tnbnc.um L.). 11. Certain physical and chemical characters. Can. J. Genet. Cytol. 27: 92-100. Genetic analyses of flue-cured tobacco leaf physical characteristics (percent lamina, lamina weight, and filling value) and chemical characteristics (percent total alkaloids, reducing sugars, nitrogen, ash, and cellulose) were conducted on a five parent diallel set (excluding reciprocals) evaluated at the Delhi Research Station in a randomized block design over a 2-year period. The ANOVA indicated that there was variance associated with the genetic source for all characteristics except filling value. Griffing's analysis for variances owing to general and specific combining abilities suggested additive genetic variance as the main source of genetic variation. Variances owing to specific combining ability for all traits were exceeded by the variance of the estimates indicating dominance to be of no major consequence in the expression of these physical and chemical traits. Total alkaloids and percent nitrogen expressed maximum heritability, and W,-V, graphs supported the conclusions. Parental diversity was evident from the scatter of array points and graphic analysis also indicated lack of dominance. Examination of pleiotropic effects revealed that traits related positively with alkaloids and nitrogen were negatively correlated with carbohydrate fractions such as reducing sugars and cellulose. Key w0rd.s: tobacco, heritability, dominance, additive effects. PANDEYA, R. S., V. A. DIRKS, G. POUSHINSKY et B. F. ZILKEY. 1985. Quantitative genetic studies in flue-cured tobacco (Nicotianc~ tnbncum L.). 11. Certain physical and chemical characters. Can. J. Genet. Cytol. 27: 92-100.Des analyses genetiques portant sur des feuilles de tabac traitees a I'air chaud ont ete poursuivies chez un groupe de cinq parents dialleles (excluant les reciproques) evalues par blocs casualises sur une pkriode de 2 ans, a la Station de Recherche de Delhi. Les caracteristiques considerees furent, sur le plan physique, les pourcentages de limbes, du poids des limbes et de la valeur de remplissage et, sur le plan chimique, les pourcentages en alcaloi'des totaux, en sucres reducteurs, en azote et en cellulose. L'ANOVA (I'analyse de variance) a indique que de la variance etait associee a la source genktique pour la plupart des caracteres, sauf pour la valeur de remplissage. L'analyse de Griffing, pour les variances dues aux aptitudes de combinaisons generales et. specifiques, suggere une variance genetique additive comme principale source de variation genktique. Les variances dues a I'aptitude aux combinaisons specifiques pour tous les caracteres ont ete surpassCes par la variance des estimes, ce qui indique que la dominance n'a aucune consequence majeure sur I'expression de ces caracteres physiques et chimiques. Les alcaloi'des totaux et le pourcentage d'azote ont exprime le maximum d'heritabilite et les graphiques W,-V, ont ap...