Growth Substances in Relation the the Rooting of Salix fragilis Cuttings

An attempt has been made to correlate seasonal variations inthe rooting responses of Salix fragilis cuttings with theircontent of growth-promoting substances. Although they were bothlow in early dormancy and higher in late dormancy and in summerthere was not an exact correlation in all months. It was found that extracts of S. fragilis cuttings taken indormancy strongly inhibited the action of IAA on the growthof Avena coleoptile segments. This inhibitory influence wasless in extracts of cuttings taken at the end of dormancy andin summer. Extracts of cuttings which had been left in waterto root showed a striking decrease in their inhibitory actionon IAA.