In a partial diallel mating design, seven ecotypes of Arabidopsis thaliana, from wide geographical locations in Europe, were examined along with their F1 hybrids for their response to supplementary ultraviolet-B (UV-B) radiation. Morphological characters included plant height, number of shoots and branches, and rosette diameter. Reproductive and total dry mass and time of flowering were also examined. The plants under treatment received 8-12 KJD-1 of biologically effective UV-B radiation while the control plants did not receive any UV-B radiation. Although strong genotype effects were observed for all the characters, a significant treatment effect was detected only for height and the reproductive mass. This effect was marginal for rosette diameter and the total dry mass. Significant genotype X treatment interactions were found for height, rosette diameter, and the reproductive mass. Except for time of flowering, highly significant values were found for the genotype X replication interactions.

Key words: Arabidopsis thaliana, diallel mating design, ultraviolet-B radiation