Rooting Ability of Willow Cuttings

Abstract

This study was conducted to clarify the rooting ability of 6 willow species, and the relationship between seasonal changes in the rooting ability of cuttings and the content of endogenous factors in comparison of easy- and difficult-to-root willows.
Among easy-to-root willows there were Salix koriyanagi, S. gilgiana, S. babylonica and S. alba, and among difficult-to-root willows there were S. bakko and S. vulpina. Cuttings of S. koriyanagi, an easy-to-root willow, rooted readily throughout the year irrespective of NAA treatment. Cuttings of S. bakko, a difficult-to-root one, rooted poorly without NAA treatment. With NAA treatment, however, they rooted well from July to October, but did poorly thereafter.
No differences in the activity of extracted auxin, nor in the content of total phenols were found between the easy- and difficult-to-root willows. The root promoting activity of water extract was always higher in the easy- than difficult-to-root willows, but it did not seem to participate in the seasonal changes in rooting ability in both the easy- and difficult-to-root willows, because of the lack of the correlation between them. In S. koriyanagi with and without NAA treatment and S. bakko without NAA treatment, there were no significant correlations between seasonal changes in the rooting ability and in the activity or content of endogenous factors. Only in S. bakko with NAA treatment, however, a significant correlation was recognized between the rooting ability and the activity of extracted auxin.