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Analyses of ash provenance trials

We measured and analysed provenance trials consisting of 52 provenances, mainly German (42) in origin, & planted in 1987. First results have shown significant differences between provenances for height and circumference data and genotypic heritability varied between 0.32* and 0.76*** on the two sites examined. The coefficient of phenotypic variation decreased with time; it ranged from 15-19% for data collected in 1990 to 5-6% for data collected in 2000. The analysis of data on stem form and crown form showed very highly significant differences among provenances and heritability was characterised as medium to very low (from 0.68 **** to 0.26 NS).

Provenance effects were also very highly significant for frost damage at two sites and genotypic heritability was good (from 0.60 *** to 0.72***). The genotypic hertabilities and gains were computed after a multi site analysis of all characters measured. This showed that provenance effect was highly significant for height growth but not for height increment and stem girth. Height heritabilites were 0.78*** from 1990 growth data, decreasing to 0.53** for 2000 data. Provenance effect was at least, significant for crown and stem form giving genotypic heritabilities from 0.44* to 0.77***.

In collaboration with oterh project partners, a global statistical analysis of all of the data from 16 yr old trees from 46 provenances which were established in France and Germany in 1987 was undertaken on the characters of height, girth, stem form, forking and frost resistance. It showed that the provenance, site and interaction effects for girth and height were all very highly significant. The site effect was the most significant, followed by provenance and interaction effects.

An analysis of stem form showed a similar effect of site over provenance. In summary these results indicate the strong influence of site on the performance of ash trees, and that selection for important characters such as stem form can be made at the levels of provenance and progeny. However it was also noted from the global analyses a strong site effect and that selection of the best provenances may be valid for local and regional superiority only.

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