The effect of epistasis on chromosome mapping of quantitative characters in wheat. II. Agronomic characters

Abstract

Chromosome mapping of agronomic characters in wheat was attempted using the complete chromosome substitution series for both 'Hope' and 'Kenya Farmer' varieties as donors and 'Chinese Spring' as recipient variety, grown in replicated yield trials at four sites in South Australia. Grain yield, fertile tiller numbers, 1000-grain weight, fertile spikelets per spike, total dry weight, spike length and green tiller number were estimated from plot subsamples. Overall between chromosome interactions were found for all characters except total dry weight at one or more sites. The patterns of substitution line effects were similar for both series and did not correspond to differences between donor and recipient varieties. Within site variation was low relative to treatment effects at two sites. Sixty four significant substitution line effects were detected in the Hope series, and 67 in the Kenya Farmer series. A simple additive model for the effects of substituted chromosomes was inadequate because of epistasis. Overall epistatic effects can be predicted from the selection history and adaptation pattern of the recipient variety. Genes from the donor variety for complex growth characters cannot be satisfactorily mapped by substitution line analysis.