RELATIONSHIP BETWEEN ENVIRONMENTAL STABILITY OF CULTIVARS AND THEIR ADOPTION IN THE AUSTRALIAN PROCESSING TOMATO INDUSTRY

The Australian processing tomato industry relies on the introduction of improved cultivars in order to remain internationally competitive. To make identification of potential new cultivars more efficient and effective, it is important to understand the basis for their selection by the industry. Criteria may include performance and environmental stability of critical traits. With such a variable production environment, it is assumed that the Australian industry relies on robust environmental stability rather than exploiting favourable genotype-environment interactions for each growing region. The type of stability exploited and the importance of four economically important traits (yield, soluble solids content, field holding ability and juice colour) were explored using data from replicated cultivar evaluation trials conducted throughout northern Victoria and southern New South Wales during the 2001/2002 season. Mean performance, significant differences and environmental stability of traits were calculated and the occurrence of any favourable bias for above-average performance of traits or their stabilities was determined. Three factors were shown to be important in cultivar selection; increased yields, increased holding ability and environmental stability of soluble solids. The assumption that environmental stability is a key factor in the selection of cultivars for the Australian industry has proven to be false for three of the four traits measured and an opportunity exists to actively select for greater stability. This work represents an attempt to explain cultivar choice in the Australian processing tomato industry using four key traits and their environmental stabilities and starts to establish a selection framework. This approach is discussed as the basis for future cultivar selection programs.