Tobacco (Nicotiana tabacum L.) plantlets were grown in vitro and for the last subculture 10 μM abscisic acid (ABA) was added to the medium. After three weeks plantlets were transferred into pots with Perlite and grown either under low or high irradiance of 150 (LI) and 700 (HI) μmol m-2 s-1, respectively.
After ex vitro transfer, stomatal conductance and transpiration rate decreased considerably in comparison with in vitro grown plantlets and remained lower also 7 d after ex vitro transfer, especially in ABA-treated plants and so wilting of plants was practically eliminated. Water use efficiency significantly increased in ABA-treated plants.
Contents of xanthophyll cycle pigments and ABA precursors (neoxanthin and violaxanthin) were lower in ABA-treated plants than in control plants indicating less stress in these plants.