The effect of light quality on growth, photosynthesis, leaf anatomy and volatile isoprenoids of a monoterpene-emitting herbaceous species (Solanum lycopersicum L.) and an isoprene-emitting tree (Platanus orientalis L.)

The effect of different light qualities on growth, photosynthesis, leaf anatomy and isoprenoid emission was studied in two plant systems: a herbaceous crop, tomato, and a tree, oriental plane. Both plant species were subjected to three different light quality regimes: RGB (Red 33%, Green 33%, Blue 33%) and RB (Red 66%, Blue 33%), provided by light emitting diodes (LED); and white light (WL), provided by white fluorescent lamps. Compared to WL, RGB and RB reduced plant height, plant biomass and leaf area. The CO2 assimilation rate (A) was lower in tomato grown under WL than RGB and RB, while A was similar in oriental plane exposed to the three light regimes. In tomato, stomatal (gs) and mesophyll (gm) conductance were higher under RGB and RB compared to WL. In plane, gs was also higher under RGB and RB, while gm was not significantly influenced by different light qualities. In both species, leaf lamina thickness (LT) and stomata size were the anatomical traits most affected by the different light regimes. In tomato, leaf lamina thickness was significantly reduced in RGB and RB leaves, whereas in oriental plane leaf lamina thickness was significantly higher in RGB and RB than in WL leaves. In both species, RB leaves showed bigger stomata size than WL and RGB leaves. Light quality also affected photosynthesis- dependent volatile isoprenoids. In tomato, b-phellandrene was lower under RB and RGB compared to WL. However, RGB and RB stimulated a-pinene, carene and a-terpinene emissions. Oriental plane released about 14 nmol m-2 s-1 isoprene when growing at WL, while the emission was reduced under RGB and even more under RB. In summary, photosynthetic performance, leaf anatomy, biomass production, and volatile isoprenoids are affected by light quality differently in tomato and plane plants. Light quality control may have important applications to modulate plant productivity and increase biosynthesis of useful biochemical compounds.