Effects of gamma radiation on microcuttings of plum (Prunus salicina Lindl.) 'Shiro'.

Abstract

In vitro cultures of the Japanese plum ( Prunus salicina Lindl.) 'Shiro' were irradiated with different doses of gamma rays. Microcuttings were subjected to acute irradiation (530 Rad/min) for total doses of 0, 10, 20, 30 or 40 Gy. After gamma-ray irradiation, shoots were transferred to a proliferation medium. In the first subculture no mortality was recorded for unirradiated control shoots or for shoots treated with 10 Gy, while with 20, 30 and 40 Gy, mortality rates of 5%, 29% and 64%, respectively, were recorded. Proliferation rate of irradiated shoots differed from the unirradiated control only when treated with 30 or 40 Gy. Microcuttings originated from shoots irradiated with 30 and 40 Gy showed a reduced rooting capacity. The dose which gave the total reduction in growth closest to LD50 was 30 Gy, for which a 55% total growth reduction was recorded. Lower doses were not effective enough, while 40 Gy was too high, causing a total growth reduction of 81%. A survey orchard was established with self-rooted trees deriving from irradiated shoots. Some variants for vegetative and fruit traits were observed.