Subtle changes in light intensity affect in vitro responses but not ex vitro performance of Limonium sinuatum

Environmental conditions during the in vitro stages of a micropropagation process can further affect the ex vitro plant performance. In this work, the behaviour of four blue cultivars of statice (Limonium sinuatum) was studied with respect to four distances (18.0, 12.5, 8.0, or 2.0 cm) between culture tubes and the light source during their in vitro multiplication stage. In vitro shoots of statice were cultured on MS medium supplemented with 4% sucrose, 0.9% agar and 0.2 mg L^-1 BA and incubated under four slightly different light intensity treatments (PPFD of 96.9, 99.6, 101.2, or 102.7 µmol m^-2 s^-1) for 35 days at 23 °C with a daily photoperiod of 16 h. The light treatments assayed resulted in no significant differences in in vitro propagation ratio and ex vitro survival and crop production and quality (as judged by the number of inflorescence stems per plant, length of inflorescence stems and number of both spikes and branches per stem produced). However, in vitro growth (estimated as the length of the longest leaf in a shoot at the end of the culture period) and levels of pigments (chlorophylls and carotenoids) and antioxidants (as estimated by the DPPH test) showed variations among cultivars. This indicates that statice cultivars were able to adjust their metabolism in response to the small differences in light intensity of the treatments applied. Results point to the importance of optimization of growth room use to increase profitability of micropropagation processes.