Influence of nitrogen nutrition on growth and accumulation of rosmarinic acid in sweet basil (Ocimum basilicum L.) grown in hydroponic culture

摘要

Sweet basil (Ocimum basilicum L. cv. Genovese) was grown in hydroponic culture (floating raft system) for the extraction of rosmarinic acid (RA). Two experiments were undertaken to investigate the influence of nitrogen (N) nutrition on biomass and RA production. Sweet basil seedlings were cultivated for seven weeks from April to July of 2009, under the typical greenhouse conditions of Mediterranean regions. The nutrient solutions contained different NO -3 concentrations (0.5, 5.0 and 10.0 mol m -3) or NO -/NH +3 4 molar ratios (1:0, 1:1 and 0:1; total N concentration was 10.0 mol m -3). The concentration of other nutrients were as follows: 1.0 mol m-3 P-H2PO4, 10.0 mol m -3 K+; 3.0 mol m-3 Ca2+; 1.5 mol m-3 Mg2+ plus trace elements. Plants were harvested at full bloom and RA was quantified by HPLC in roots, stems, inflorescences and leaves. In both experiments, sweet basil produced a large amount of biomass with relatively high RA concentration, which ranged from approximately 10 to 97 g kg-1 DW in leaf tissues, depending on leaf age and N nutrition. The use of a total NO - 3 concentration of 5.0 mol m -3 resulted in optimal plant growth and RA production; this suggests that the standard N concentration used in hydroponic culture (10.0 mol m-3 or higher) could be reduced considerably, with important implications from the environmental point of view. In contrast, the addition of NH + 4 to the nutrient solution was detrimental to both growth and RA production.