Analysis of line x environment interactions for yield in navy beans. 1. Components of variance

Multi-environment yield trials of navy bean (Phaseolus vulgaris L.) lines w ere grown over a diverse range of locations for the years 1983-1989 in Quee nsland, in an unbalanced set of line x location x year combinations. This i s the first in a series of 3 papers reporting different perspectives on the genotype x environment (GxE) interactions in this series of experiments. I n this paper, restricted maximum likelihood (REML) estimates of GxE compone nts of variation were derived using trial means in both standard and extend ed models where concomitant genotype and location factors such as maturity, disease resistance, and experimental management regimes were investigated. Prior to estimating the variance components the heterogeneity of trial err or variances was modelled. Several alternative trialing systems were compar ed using acceptance probabilities derived from the variance components. The interaction of genotype maturity with location considerably reduced the li ne x location x year variance component and further examination of the matu rity x environment interaction suggested an advantage in stratifying the br eeding program on maturity. There is no redundancy in the current trialing system and an increase in sampling locations can be justified.