Atlas: Analysing GxE interactions in lupin variety x time of sowing trials using GenStat by Bob French

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Australasian Genstat Conference 2002
December 4-6, 2002

Busselton, Western Australia, Australia

Organizers
Jane Speijers - Convenor Organising Committee, Peter Clarke - Chairman Programme Committee

Analysing GxE interactions in lupin variety x time of sowing trials using GenStat
by
Bob French
Department of Agriculture, Western Australia and Centre for Legumes in Mediterranean Agriculture, University of Western Australia
Coauthors: Mario D’Antuono (Department of Agriculture, Western Australia)

Since the mid-1990s six narrow-leafed lupin cultivars have been released in Western Australia, expanding the range of cultivars growers have to choose from. This raises the possibility that growers could exploit genotype × environment (G×E) interactions by choosing different cultivars for different environmental niches. Eight lupin cultivars (including one yellow lupin cultivar) were tested at five locations in WA from 1998 to 2000 at four different sowing times. Split-plot designs were used for all of these experiments with time of sowing as the main-plot.

Among the narrow-leafed cultivars the total G×E variance was 1.9 times the cultivar variance. 13% of the G×E variance was explained by differences between cultivars in their linear response to sowing date. Most of the rest of the G×E variance was associated with differences between years. These data suggest that there is little opportunity to select lupin cultivars specifically for early or late sowing.

We discuss some of the modelling procedures used in the standalone program ASREML (NSW Agriculture) and describe some features available in GenStat to do similar modelling. We also consider what improvements there are with a combined spatial analysis especially in the situation of combining split-plot designs. Furthermore, we discuss the use of bi-plots and the how they can be used to summarise the GxE matrix using a special interface from GenStat procedures to link other graphical programs to achieve a broader control of the graphical summaries.

Date received: November 18, 2002