Masters Theses

Date of Award


Degree Type


Degree Name

Master of Science



Major Professor

Creighton L. Gupton

Committee Members

E. Gray, J. W. Hilty


The Inheritance of Resistance to Isolates of Fusarium oxysporum var. nicotianae in Hurley Tobacco. (Under the direction of CreightonLee Gupton).

The objectives of this study were: (1) to determine the mode of inheritance of resistance in hurley tobacco when using individual isolates of Fusarium oxysporum and (2) to estimate the genetic parameters conditioning resistance. Five hurley tobacco varieties which range from highly resistant to susceptible were crossed in a diallei scheme to provide the genetic material for the study. Plants were subjectively evaluated for their disease reaction as six-week old seedlings in the greenhouse.

The population means of the P1, P2, F1, F2, P1F1 and P2F1 generations of each cross were subjected to a generation means analysis to determine the genetic effects involved in resistance to the Fusarium isolates. The Fj means were also evaluated for their general and specific combining ability.

Although a statistical difference in virulence was found among the isolates, and at least two physiological races were represented among them,the mode of inheritance and genetic effects for resistance appeared to be very similar for each isolate.

Results indicated that resistance of hurley tobacco to the Fusarium isolates used in this study was quantitatively inherited and that general combining ability and additive gene effects were of major importance.Dominance and epistatic effects were also important in some populations and isolate combinations.

It was concluded that the tobacco breeder can effectively use a mixture of Fusarium isolates when breeding for Fusarium wilt resistance.The breeding program should be designed to accumulate genes for resistance into pure lines since genetic effects are predominately additive.

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