THE EFFECT OF GAMMA-IRRADIATION ON GROWTH-CHARACTERISTICS AND ARBUTINCONTENT OF BEARBERRY (ARCTOSTAPHYLOS-UVA-URSI, CV ARBUTA)

Between 1986 and 1989 we studied the influence of gamma-irradiation (2 .5 - 80 Gy) on growth processes and the content of arbutin glycoside. Bearberry [Arctostaphylos uva-ursi (L.) Sprengel] shows polycyclic cha racteristics of growth; the vegetation period is divided by summer dor mancy (June) into periods of spring and summer growth. As plants age t he summer dormancy gets longer and the period of summer growth is shor ter. Irradiation with a dose of 80 Gy was lethal and a dose of 60 Gy d amaged plants so much that they were not able to grow in the first spr ing after irradiation. Significant growth stimulation (both in the hei ght of plants and in branching) was shown only in the second year afte r irradiation (2.5 - 60 Gy). In the fourth year the growth in all irra diated variants was weaker than in the control. Doses of 2.5 and 5 Gy did not influence the content of arbutin significantly; higher doses o f irradiation changed the dynamics of production and decomposition whi ch is connected with growth changes.