Growing basil in the underwater biospheres of Nemo's Garden®: Phytochemical, physiological and micromorphological analyses.

• Nemo's Garden® underwater biospheres are a green, alternative agriculture system. • Underwater basil did not show micromorphological changes of the leaf indumentum. • Relevant differences were detected in the essential oil and head space compositions. • More photosynthetic pigments and polyphenols were produced in the underwater plants. • Basil seems well adapted: studies on other species are needed to evaluate a scale-up. The need for alternative cultivation methods is urgent for regions of the world where cultivable land is scarce: underwater areas are unexploited and vast. Nemo's Garden® Project aims at creating a green and alternative agriculture system: its biospheres are underwater greenhouses, developed for areas where plants growth is difficult in terrestrial conditions, due to climate change. Basil was chosen as model plant to study its phytochemical, physiological, and micromorphological parameters, in comparison with the same plants grown in terrestrial conditions in the Sanremo Research Centre for Vegetable and Ornamental Crops (CREA-Centro di Ricerca Orticoltura e Florovivaismo) greenhouse. While the micromorphological analyses showed no detectable differences between control and biospheres samples, the phytochemical investigations evidenced a switch of the essential oil chemotype from methyl eugenol/linalool to methyl eugenol, respectively. The headspaces were also different: sesquiterpenes dominated the biospheres samples, whereas oxygenated monoterpenes accounted for half the control sample emission. Differences also emerged in the physiological investigation: total chlorophyll, total carotenoids and total polyphenols were present in higher amounts in the biospheres samples, with a 31.52% and 13.3% increase in the antioxidant activity and polyphenols content, respectively. Basil was well adapted in the biosphere environment, whose influence should be studied in different species to assess the viability of an industrial scale-up of the Nemo's Garden®. [ABSTRACT FROM AUTHOR]