The acid phase of methanolic extracts of Picea glauca var. albertiana cv. Conica tissue, a difficult-to-root cultivar, had a high content of substances, at Rf 0.9 – 1.0, which inhibited the growth of Avena first internode. Chamaecyparis lawsoniana var. fletcheri, an easy-to-root variety, had a lower content of these substances. The substances stimulated root formation in mung bean cuttings, but no synergistic root-promoting effect was found when they were supplied to mung bean cuttings in the presence of 5 × 10−6M indoleacetic acid (IAA).
The substances at Rf 0.9 – 1.0 showed a dose-response effect over a concn range of 0 to 1.106 g fresh wt. Concn higher than 1.106 g did not further increase the number of roots in either species. An additive effect between extract and IAA was found in Picea at concn below 0.276 g and in Chamaecyparis at concn lower than 0.110 g and higher than 1.106 g fresh wt. The possibility that root initiation may be determined by hormone balance rather than a single substance is discussed.