Can Commercial Sorghum Lines be Made Resistant to Ergot Damage?
by
Scott Foster
Queensland Government's Department of Primary Industries
Coauthors: Damian Herde (Queensland Government's Department of Primary Industries)

Ergot (Claviceps africana) is a floral pathogen of grain sorghum (Sorghum bicolor). The pathogen colonises only the flowers of the plant, replacing them with a toxic fungal mass. Resistance was identified in a non-commercial and low yielding line. Ergot resistance is a quantitative trait, meaning it is greatly influenced by environmental effects, and possibly controlled by many genes (which can result in low heritability of the trait). A natural question is: can the resistance genes be bred into commercial lines?

A generation means experiment was carried out near Warwick, Queensland. It contained populations that were based on the resistant line crossed with a highly susceptible line and also a moderately susceptible line (with reference varieties added for comparison).

The severity of the ergot damage (as measured by percent of flowering head affected by ergot) is dependent on time. The time effects will need to be removed before any inference can be made about the genetics. The effect of time seems to be different for each genetic line, which makes any inference about genetical parameters more difficult.

In this talk methods of removing the time effect are presented along with what to do with estimating genetical parameters for the time varying responses.

Date received: August 29, 2002