Quantitative inheritance of Fiji disease resistance in sugarcane

Abstract

The inheritance of Fiji disease resistance in sugarcane was studied, so that strategies for breeding for resistance could be developed. Resistance was highly heritable and most of the genetic variance was additive when infection pressure was low to moderate. Infection pressure was very heavy in one experiment and this reduced discrimination between parent clones and families. The data were skewed and this affected statistical and genetical analyses which showed that non-additive genetic variance was high. In general, however, it was concluded that selection of resistant parents would produce families with resistant progeny. Some moderately susceptible families produced a small number of resistant progeny and, if these families have agronomic merit, the breeding strategy should enable such families to be planted. The computerised strategy adopted rejects crosses if the average susceptibility of the two parents is too high, and emphasises the use of more resistant parent clones. As some susceptible clones will be selected, clones are subjected to a field screening trial as soon as practicable. These strategies have reduced the percentage of susceptible clones in the population from 70–80% to 20–30%.