EFFECTS OF ELEVATED CO₂ ON ACCLIMATIZATION OF IN VITRO-REGENERATED CHESTNUTS: GROWTH ANALYSIS

In this study, we present the results of growth analysis of in vitro-regenerated chestnut hybrid plantlets (Castanea sativa × C. crenata), during the acclimatization stage, using two CO₂ concentrations (350 and 700 µl L^-1) at 250 µmol m^-2 s^-1 as irradiance level (PPFD). Elevated CO₂ did not affect the survival rate and it was susceptible to increase progressive autotrophy, expressed by a significant increase in relative growth, shoot/root ratio and leaf area ratio (LAR). The plants under elevated CO₂ showed a higher stomatal frequency but the new leaves developed at the end of acclimatization revealed a gradual normal stomatal morphology and they reduced the stomatal frequency.
Their morphology showed an effective water loss control which is one of the most important problem during this critical phase of the autotrophic competence acquiring process.
The net photosynthesis rate was similar in both treatments but the plants acclimatized at elevated CO₂ showed an increase in maximum photosynthetic rate (A_max), and this can lead to a better physiological development.
We think that the gains that we have achieved with the use of elevated CO₂ can be more significant if a higher light intensity can be used instead because they have a better response capacity to an increment of the level of irradiance.

II International Symposium on Acclimatization and Establishment of Micropropagated Plants

M.T. Coelho, M.G. Diogo, J.C. Gonçalves

acclimatization, chestnut, growth analysis, CO₂, autotrophy

https://doi.org/10.17660/ActaHortic.2007.748.19