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Protoplast preparations from barley (Hordeum vulgare L.) enzymatically converted [5-3H]tryptophan to [3H]indole-3-acetic acid (IAA). Both a chloroplast and a crude cytoplasmic fraction, isolated from protoplasts that had previously been fed [5-3H]tryptophan, contained [3H]IAA. Chloroplast and cytoplasmic preparations, isolated from protoplasts and thereafter incubated with [5-3H]tryptophan, also synthesized [3H]IAA, although, in both instances the pool size was less than 50% of that detected in the in-vivo feeds. There were no significant differences in the amounts of [3H]IAA that accumulated in protoplast and chloroplast preparations incubated in light and darkness.

Incubation with acetone and dichloromethane had little effect on the germination of different lots of Norway spruce seeds. This was not the case with Scots pine where almost half the seed lots tested were adversely affected by acetone and dichloromethane. The auxins indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) were applied to Scots pine seeds in acetone, dichloromethane and phosphate-citrate buffer. The uptake of the two compounds was most rapid from acetone. Although the uptake from dichloromethane was slower than from acetone it reached the same level after 6 h. Uptake of the growth regulators from buffer was significantly lower than from the organic solvents. The accumulation of IAA and IBA into the seeds from both acetone and dichloromethane was linear between 0.5 and 10 mM, and between 0.5 and 15 mM from buffer. IAA and IBA levels in infused seeds declined over a 5-day germination period, the former more rapidly than the latter. The metabolic activity of the IAA degradation system was as effective in seeds after immersion in the organic solvents as seeds immersed in buffer.

Nine seed lots each of Norway spruce (Picea abies L.), and Scots pine (Pinus sylvestris L.) were treated with combinations of the growth regulators: Indole-3-acetic acid, indole-3-butyric acid, etephone, kinetin, fusicoccin, and the gibberellins A1 A3 A4/7, and A9. GA9 GA4/7 and fusicoccin significantly promoted the germination of five Norway spruce, and three Scots pine, seed batches. Independent of species, the germinability of seeds treated with auxins, etephone, kinetin, GA1 and GA3 were unaffected or reduced. The rate of germination was stimulated for both species when treated with GA9 or GA4/7. The germination percentage for Scots pine seeds was enhanced by GA9 but not by GA4/7. Neither of the two GAs enhanced the germination percentage of Norway spruce seeds.