Stock plant nutrition and stem cutting water relations during propagation of four woody nursery crops

Abstract

To evaluate the effects of stock plant nutrition and propagation medium moisture content on stem cutting propagation, two separate studies were conducted. In one study, stem cuttings of Juniperus horizontalis Moench ‘Wiltonii’, Rhododendron (Lindl.) Planch ‘Hino-Crimson’, and Ilex crenata ‘Helleri’, were propagated in 1 peat : 1 perlite (v/v) at 125 %, 250 %, 375 %, 500 %, and 625 % moisture. Stem cutting survival and rooting, midday xylem water potential, and basal water uptake all generally increased with increasing medium moisture level. Incidence of cutting basal rot was not directly related to medium moisture level, but was related to species and growth stage of the stock plant. Basal water uptake by cuttings was highest during the first few days after insertion and thereafter decreased until root emergence. Propagation was most successful in the wettest medium (625 %).

In a second study, containerized stock plants of Ilex crenata Thunb. ‘Rotundifolia’ were liquid-fertilized with 25, 50, 100, 200, and 300 mg N · liter⁻¹ in two forms (100 % NH₄NO₃ or 50 % Urea + 50 % NH₄NO₃) in a factorial treatment design. Percent rooting of stem cuttings decreased linearly with fertilizer rate. Leaf and stem percent N increased from suboptimal to excessive levels with fertilizer rate. Total nonstructural carbohydrates (TNC) levels increased in leaves and remained constant in stems with increasing fertilizer rate. Stem cutting percent moisture was highly correlated with fertilizer rate. The form of N applied made no statistical difference in these trends. The decrease in percent rooting with increasing fertilizer rate was attributed to increases in shoot growth activity.