Comparative greenhouse study of Eucalyptus grandis in vitro plantlets and half-sib seedlings, I. Net photosynthesis.

Tissue culture-derived plantlets from three superior five-year-old Eucalyptus grandis Hill ex Maid hybrids were compared to their related half-sib seedlings under greenhouse conditions. Net photosynthesis, chlorophyll a and b concentrations, and nitrogen concentration were sampled four times at 40-day intervals. Comparisons were started 40 days after plantlets and germinating seedlings were moved from mist to greenhouse conditions. Seedlings had higher net photosynthesis, chlorophyll and nitrogen concentration at early harvests. However, as the study progressed the difference between plantlets and seedlings decreased and reached similar values. No family differences were observed regardless of plant origin (seedlings or plantlets). Plantlets and seedlings showed similar general trends in all the measured parameters over the four harvests.