In vitro [14C]-labelled 6-benzyladenine uptake and14CO2 evolution in two Japanese plum cultivars

Japanese plum cultivars Obilnaga and Santa Rosa showed different proliferation responses when grown in similar conditions in vitro. This led us to investigate BA uptake by shoots of both cultivars grown for different times (15 hrs, 1, 3, 6, 9, 13, 16 and 20 days) on an incubation medium enriched with 10Ci (370 kBq) 8-¹⁴C]BA/250 ml. The decrease of radioactivity in the medium and its increase in the EtOH-soluble and-insoluble fractions of shoots of both cultivars grown for different times (15 h, 1, 3, 6, 9, 13, 16 and 20 days) on cultivars. Increasing amounts of¹⁴CO₂ were detected in the culture atmosphere when shoots were grown in gas-tight vials. The type of container closure strongly affected proliferation. From the results reported here it is not possible to state whether different optimal subculture intervals and different proliferation responses of Santa Rosa and Obilnaja cultures are due to different tissue sensitivity to the cytokinin and/or to different metabolic activities. Nevertheless the highest proliferation rates of both plums are clearly related to a drop of EtOH-soluble radioactivity of shoots by the end of subculture.This paper is No. 620 of the Istituto di Coltivazioni Arboree. Part of the results were presented as a poster at the 15th International Symposium on Growth Regulators in Fruit Production, Rimini (Italy) 2–6 September 1985. The research was partially supported by funds of the Ministry of Education, Roma (M.P.I. 60%).