Effects of atmospheric CO2 enrichment on the growth and development of Hymenocallis littoralis (Amaryllidaceae) and the concentrations of several antineoplastic and antiviral constituents of its bulbs

Two 2-yr crops of tropical spider lily (Hymenocallis littoralis) plants wer e grown in field soil in clear-plastic-wall open-top enclosures in the Sono ran Desert environment of central Arizona. Half of the plants were exposed to ambient air of 400 ppm atmospheric CO2 concentration and half of them we re exposed to air of 700 ppm CO2. This 75% increase in the air's CO2 conten t resulted in a 48% increase in aboveground plans biomass and a 56% increas e in belowground (bulb) biomass. is also increased the concentrations of fi ve bulb constituents that have been demonstrated to possess anticancer and antiviral activities. Mean percentage increases in these concentrations wer e 6% for a two-constituent (1:1) mixture of 7-deoxynarciclasine and 7-deoxy -trans-dihydronarciclasine, 8% for pancratistatin, 8% for trans-dihydronarc iclasine. and 28% for narciclasine. for a mean active ingredient percentage concentration increase of 12%. Combined with the 56% increase in bulb biom ass, these percentage concentration increases resulted in a mean active ing redient increase of 75% for the 75% increase in the air's CO2 concentration used in our experiments.