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in vitro plants are grown in an artificial environment, this leadiag to the development of a number of physilological charact,eriitics. In 'this experiment the gowth ad fhotosynthetic performanre of wild cherry
(Pnmus avium) cultured under different growtil. conditions, both in vitro and ex vitro (after 1 a&II 4 weeks) were investigated. Maximum photosynthetic rate (Pm) for in vitro plantlets was 1.3 nrlcromol Co2 m-2 s-l. Pm increased approximately 4 fold, two weeks after being transferal jato ex vitro, as compared to originally ex
vitro plantlets. In this experiment leaf biomass accumulation and leaf area in vitro were lower, as consistent with Pm. No relations were found between Pm, leaf chlorophyll (a+b) content, and a:b ra1l:io. Both a low
Ruhisco activity and a reduced electron transport capacity of in vitro plantlets underlie the low Pm. Since the leal nitrogen concentration of in vitro plantlets was significantly higher than that of plantlet:s _wn ex vitro it
can he assumed that Rubisco activity rather than amount of this enzyme limits the Pm of in vi1l.[10 plantlets.