Chlorophyll fluorescence as an indicator of photosynthetic functioning of in vitro grapevine and chestnut plantlets under ex vitro acclimatization
2001
Carvalho, L.C. | Osorio, M.L. | Chaves, M.M. | Amancio, S.
This study reports the effects of light availability during the acclimatization phase on photosynthetic characteristics of micropropagated plantlets of grapevine (Vitis vinifera L.) and of a chestnut hybrid (Castanea sativa x C. crenata). The plantlets were acclimatized for 4 weeks (grapevine) or 6 weeks (chestnut), under two irradiance treatments, 150 and 300 micromol m-2 s-1 after in vitro phases at 50 micromol m-2 s-1. For both treatments and both species, leaves formed during acclimatization (so-called 'new leaves') showed higher photosynthetic capacity than the leaves formed in vitro either under heterotrophic or during acclimatization (so-called 'persistent leaves'), although lower than leaves of young potted plants (so-called 'greenhouse leaves'). In grapevine, unlike chestnut, net photosynthesis and biomass production increased significantly with increased light availability. Several parameters associated with chlorophyll a fluorescence indicated photoinhibition symptoms in chestnut leaves growing at 300 micromole m-2 s-1. The results taken as a whole suggest that 300 m-2 s-1 is the upper threshold for acclimatization of chestnut although grapevine showed a better response than chestnut to an increase in light.
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