Growth and metabolism of basil grown in a new-concept microcosm under different lighting conditions

To simulate a typical market-oriented cultivation in laboratory, plants of basil (Ocimum basilicum L.) were grown from seedling to flowering stages in a new-concept microcosm device that enables roots and aerial parts to grow as under real crop conditions. To test the device efficacy, two microcosms were used with the same lighting architecture, temperature and photoperiodic conditions and with two different light spectra, white (W) or blue-red (BR), displaying a similar spectral power in the blue region. Plant growth, biomass yield, photosynthetic efficiency and nutrient uptake were determined. An innovative analytical approach for secondary metabolic profile was also developed to determine basil quality. The plants grew vigorous and healthy for the whole cultivation period and under both the lighting regimes, giving a biomass yield similar to those of basil grown under conventional greenhouse and field conditions. The two lighting regimes differently affected plant growth and yield, with the BR light, that was characterized by a higher photosynthetic photon flux density (PPFD), associated to higher plants, earlier flowering and greater yield. In the average, fresh and dry aerial biomasses per plant were about 250 g and 41 g under BR and about 114 g and 9 g under W light. Higher concentrations of major nutrients were detected in plants under W light, thus indicating that yield levels and major nutrient concentrations are not necessarily related to each other. Similar Fv/Fm (0.76–0.78) and ETR values were observed under the two light regimes, possibly indicating that plants under long lasting cultivation can adapt to different light regimes to reach similar photosynthetic efficiency levels. Different secondary metabolic profiles were detected in tissues sampled at the end of cultivation period and previously unreported profiles for basil were also recorded, possibly indicating that the extent of plant growth affects secondary metabolism in basil, in addition to light spectrum and PPFD level. This is the first report of basil grown under microcosm conditions from seedlings to adult plants. Our results indicate that the microcosm based-technology is effective in simulating a typical market-oriented cultivation and that long lasting cultivation emphasizes the effects of different environmental conditions on plant growth and metabolism.