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# Photoinhibition during Acclimatization of Micropropagated Spathiphyllum "Petite" Plantlets

J. M. Van Huylenbroeck, H. Huygens and P. C. Debergh
In Vitro Cellular & Developmental Biology. Plant
Vol. 31, No. 3 (Jul. - Sep., 1995), pp. 160-164
Stable URL: http://www.jstor.org/stable/4293081
Page Count: 5
Micropropagated Spathiphyllum "Petite" plantlets were acclimatized at low- or high-light intensities [photosynthetic photon flux density (PPFD) $100 or 300 \mu{mol} \cdot m^{-2} \cdot s^{-1}$]. During the first days chlorophyll fluorescence measurements show a partial photoinhibition of the photosynthetic apparatus, expressed by a decrease of the variable over maximal fluorescence ratio (Fv/Fm). This inhibition of Fv/Fm was significantly higher for plants grown at high-light intensity, leading to a photooxidation of chlorophyll. Newly formed leaves were better adapted to the ex vitro climatic condition (as shown by the increase of the Fv/Fm ratio) and had a higher net photosynthesis compared with in vitro formed leaves. Nevertheless, plants grown at $300 \mu mol \cdot m^{-2} \cdot s^{-1}$ were photoinhibited, compared with those at $100 \mu{mol} \cdot m^{-2} \cdot m^{-2} \cdot s^{-1}$. A sudden exposure to high-light intensity of 1-, 10- or 25-d-old transplanted plants (shift in PPFD from $100 to 300 \mu mol \cdot m^{-2} \cdot s^{-1}$) gave a linear decrease of Fv/Fm over a 12-h period, which was reflected in a 50% reduction of net photosynthesis. No significant interaction between day and hour was found, indicating high-light exposure causes the same photoinhibitory effect on in vitro and ex vitro formed leaves.