Effect of the nitrogen form used in the growth medium (NO3 −, NH4 +) on alkaloid production in Datura stramonium L.

Abstract

Plants of Datura stramonium var. tatula L. Torr. were cultivated on vermiculite and received two different mineral solutions. In one treatment only NO3 −-nitrogen was added, while in the other NO3 −-nitrogen was partly (20%) replaced by NH4 +-nitrogen. Total dose of nitrogen as well as interionic ratios were kept constant in both treatments. With the combined treatment (NO3 −-NH4 +) a significant higher hyoscyamine content was found at the time when highest biomass was reached. This was apparently the result of an increased alkaloid biosynthesis. Also scopolamine content was positively influenced, but only at a point past maximal biomass yield. No significant differences in amounts of nitrogen bound per plant were found between both treatments. The higher alkaloid content observed with the combined treatment was associated with a higher relative proportion of bound nitrogen present in the alkaloids. It seems that more nitrogen is available for secondary metabolism when NH4 +-nitrogen is present in the culture medium.