Performance of Twenty Four European Fraxinus excelsior Populations in Three Lithuanian Progeny Trials with a Special Emphasis on Resistance to Chalara fraxinea

Abstract

The main aim of the present study was to estimate genetic variability and the level of genetic control of disease resistance in common ash populations based on progeny testing, and to select resistant populations, families and genotypes for production of reproductive material resistant to dieback caused by Chalara fraxinea. A total of 320 half-sib families from ten Lithuanian and fourteen foreign European Fraxinus excelsior populations have been tested in three progeny trials established in Telsiai, Pakruojis, and Kedainiai State Forest Enterprises. Because of severe attacks by C. fraxinea, only 10% >f irees survived in all progeny trials at the age of eight years. Variance analysis of health condition scores revealed significant effect of genetic factors i.e., populations and families. Differences in resistance among populations were significant and ranged up to 52.8-55.1% in a degree of damage and survival rale of populations varying from 0.13 to 0.59. At the age of eight years, genetic family variance components ranged 5.3-7.5%, while the additive coefficients of genetic variation ranged 29.9-38.7% indicating the existence of strong genetic differences in progenies' resistance to C. fraxinea both at populational and family levels. There was a significant site effect on the level of damage which could be due to site conditions and'or different infection pressure from the surrounding stands. However, genotype by environment interaction (G x E) for resistance traits was weak and nonsignificant which indicated that populations and families do not differ much in their performance across environments and thus specific adaptations and genetic variation in ecological response are not pronounced