Improvement of acclimatization of micropropagated grapevine: Photosynthetic competence and carbon allocation

Grapevine plantlets multiplied in vitro were acclimatized at 40 or 90 mu mo l m(-2) s(-1) photon flux density for 12 or 16 h per day, respectively. In the high-light regime a decrease in total chlorophyll and an increase in ch lorophyll a/chlorophyll b ratio occurred. However, at high-light intensity lower photosynthetic capacities and higher apparent photosynthesis were mea sured than at the low-light regime. In leaves expanded during acclimatizati on, the light compensation point was higher in plantlets under high-light w hile quantum yield was higher in low-light conditions. High-light also gave rise to an increase in carbohydrate concentration. As a whole, the results suggest that high-light increases carbon assimilation and growth although with a low investment in the photosynthetic apparatus.