Asexual Propagation of Salix humilis Using Stem Cuttings I: Cutting Types

Abstract

Salix humilis Marsh. (prairie willow) is an underutilized native shrub willow with potential for broader application in ornamental horticulture and managed landscapes. With attractive features, winterhardiness, and adaptability to a range of site conditions, including a purported tolerance to both extremes of the soil-moisture spectrum, prairie willow may be especially valuable for urban landscapes and green infrastructure applications. Despite the broad range of settings in which the species could be used, prairie willow is unusually difficult to propagate asexually, a feature that limits clonal improvement efforts as well as its availability in the green industry. To date, there has been no formal research conducted to explore or improve asexual propagation efforts of prairie willow. Through a series of four experiments, this project aimed to help address these gaps in knowledge by evaluating different cutting types, including dormant hardwood, semihardwood, softwood, and single-node cuttings. Semihardwood cuttings rooted at 12% and dormant hardwood cuttings rooted at 56% to 88%. Single-node cuttings gradually formed roots, reaching 45% rooting at week 9, but failed to produce shoots. Plant growth regulator application significantly increased propagule rooting. Based on these findings, it is recommended that nursery production companies use dormant hardwood cuttings treated with 5000 to 10,000 ppm K-IBA.