REEXAMINATION OF THE PHOTOSYNTHETIC CAPACITY OF INVITRO-CULTURED STRAWBERRY PLANTLETS

Photosynthesis and growth of in vitro-cultured strawberry plantlets (Fragaria xananassa Duch. cv Kent) were investigated during a 4-week in vitro culture in a rooting medium and a 4-week ex vitro period. The leaves formed in vitro on a medium containing sucrose developed a positive photosynthetic capacity. At transplanting to the ex vitro environment, their photosynthetic rate was 12.76 mumol CO2/m2 per second, which was as high as that of leaves generated and grown in the greenhouse. During the ex vitro period, photosynthetic rates of in vitro-generated leaves decreased and dark respiration rates increased. However, in vitro leaves were photosynthetically active throughout the 4 weeks ex vitro. In the first 2 weeks of the ex vitro period, in vitro-generated leaves had an important contribution to the overall plantlets' photosynthetic capacity.