Influence of root hypoxia and NaCl salinity on sweet basil (Ocimum basilicum L.) grown hydroponically for the production of rosmarinic acid

Two experiments were undertaken to investigate the influence of hypoxia and NaCl salinity on sweet basil (Ocimum basilicum L.) grown hydroponically for the production of rosmarinic acid (RA). The plants were cultivated in floating raft system under greenhouse conditions for eight weeks during summer, under the typical greenhouse conditions of Mediterranean regions. In experiment 1 the plants were grown in aerated or not aerated nutrient solution, while in experiment 2 three nutrient solutions containing 2.0 (control), 25 or 50 mmo1/1 NaCl were tested. Dissolved oxygen content averaged 7.8 mg/1 and 3.2 mg/1 in aerated and not-aerated nutrient solution, respectively. The plants were harvested at full bloom and RA was quantified in both root and leaf tissues. Floating raft system provides a suitable growing method of sweet basil for agro-industrial production of RA. Both shoot growth and leaf RA content were not affected by hypoxia conditions and NaCl salinity. In contrast, the content of this metabolite in root tissues decreased or increased in response to hypoxia stress and salinity, respectively.