Determination of Indole-3-acetic Acid in Douglas Fir Using a Deuterated Analog and Selected Ion Monitoring: Comparison of Microquantities in Seedling and Adult Tree.

Indole-3-acetic acid (IAA) content in shoot tips of Douglas fir (Pseudotsuga menziesii [Mirb.] Franco) trees and seedlings was determined by combined gas chromatography-mass spectrometry using a deuterated analog (d(2)-IAA) as an internal standard and the technique of selected ion monitoring. Ratios of the peak heights of the deuterated analog internal standard to endogenous IAA revealed a slightly higher content of IAA in seedlings compared with the shoot tips collected in June. The relatively high level of IAA (2.9 micrograms per gram fresh weight) in seedlings is discussed in relation to in vitro propagation of this species.