The effects of collection date, IBA, plant gender, nutrient availability, and rooting volume on adventitious root and lateral shoot formation by Salix planifolia stem cuttings from the Ungava Bay area (Quebec, Canada)

Abstract

Salix planifolia Pursh ssp. planifolia is a shrub species presenting some potential for the restoration of disturbed sites in the Canadian Arctic and Subarctic. The performance of S. planifolia stem cuttings collected in the Kuujjuaq area, northern Quebec, was evaluated in relation to sampling period, plant gender, exogenous auxin and nutrient concentration, rooting duration, watering frequency, and soil volume. Cuttings collected in August, during the active growing season, did not perform as well as those collected in June, October, or February. The only performance variables influenced by plant gender were root number and shoot biomass, for which female cuttings were superior to males. Surprisingly, the application of indole-3-butyric acid inhibited adventitious root and lateral shoot number and biomass, particularly at the highest concentration (10 000 mg·L-1). Increased nutrient availability enhanced root, but not shoot, growth. The best performance was observed when cuttings were grown in a relatively large soil volume (200 mL), watered frequently (twice a day), and allowed a relatively long period to root (70 days).Key words: indole-3-butyric acid (IBA), nutritional status, plant gender, rooting of cuttings, Salix planifolia, sampling period.