This study aimed to assess the effects of plant growth regulators (PGRs) on stock plant production of mojave sage (Salvia pachyphylla) and ‘Avalanche’ cape daisy (Osteospermum hybrid) that received foliar sprays of the following three PGRs: 200 and 400 ppm ethephon; 250 and 500 ppm benzyladenine; and 50 and 100 ppm gibberellic acid 4 and 7 (GA4+7) plus benzyladenine. Vegetative growth [height and width growth index (GI)], the number of vegetative cuttings, and fresh weight (FW) and dry weight (DW) of the harvested vegetative cuttings data were collected. A propagation study was conducted concurrently to determine the effects of the PGR treatments on rooting vegetative cuttings. GA4+7 plus benzyladenine (50 and 100 ppm) increased the production of both mojave sage and ‘Avalanche’ cape daisy cuttings by ≥18% more than the other treatments. The GI, FW, and DW results showed similar trends across experiments 1 and 2 for each perennial. In the propagation study, the rooting percentage did not differ after 4 weeks, indicating that the use of GA4+7 plus benzyladenine in production protocols could benefit producers of both perennials.
Sean J. Markovic and James E. Klett
Sean J. Markovic and James E. Klett
The objective of these experiments was to evaluate the reaction of ‘Snow Angel’ coral bells (Heuchera sanguinea) and Orange Carpet hummingbird trumpet (Epilobium canum ssp. garrettii ‘PWWG01S’) to repeated foliar applications of three plant growth regulators at two application rates. The plant growth regulators applied during a stock plant study and followed by a propagation study were 200 and 400 ppm ethephon, 250 and 500 ppm benzyladenine, and 50 and 100 ppm gibberellic acid 4 and 7 (GA4+7) + benzyladenine. The stock plant study was conducted to assess the efficacy of plant growth regulators, vegetative growth (height and width growth index), the number of vegetative cuttings, as well as the fresh weight (FW) and dry weight (DW) of the harvested vegetative cuttings. The propagation study was conducted to determine the effects of the plant growth regulator treatments on the rooting of the vegetative cuttings. The stock plant study showed that GA4+7 + benzyladenine (50 and 100 ppm) significantly increased production of ‘Snow Angel’ coral bells cuttings compared with all other treatments. However, no significant differences in FW or DW were observed with ‘Snow Angel’ coral bells between treatments. In the propagation study, no significant difference in rooting percentage was observed after 4 weeks. The Orange Carpet hummingbird trumpet stock plant study resulted in a greater number of vegetative cuttings with GA4+7 + benzyladenine (50 and 100 ppm) and benzyladenine (250 ppm) treatments. Fresh weight of vegetative cuttings harvested from plants treated with GA4+7 + benzyladenine (50 or 100 ppm) were the lowest. The only treatment that showed increased vegetative cutting production with no effect on FW was benzyladenine (250 ppm) on Orange Carpet hummingbird trumpet.
Sean J. Markovic, Shana G. Brown, and James E. Klett
Stock plant productivity is an important concern for growers of mojave sage (Salvia pachyphylla) because this species produces more woody growth as the plant ages. The objective of the study was to determine the best growth substrate and container size combination to maximize stock plant productivity. A secondary objective was to determine whether the stock plant treatments influenced the rooting of vegetative cuttings. Three different container sizes (3, 12, and 15.5 qt) and four soilless substrates composed primarily of bark, peat, and perlite (substrate 1); bark, peat, and vermiculite (substrate 2); bark, peat, and coarse perlite (substrate 3); and peat (substrate 4) were used. The stock plant experiment was conducted using 12 treatment combinations, and a subset of those stock plants was selected randomly for the rooting study that immediately followed the stock plant experiment. Stock plants responded to substrate treatments differently. The most successful stock plants, which produced more cuttings per plant and per square foot, as well as larger cuttings, were those grown in substrate 3. Regardless of substrate, the highest number of cuttings per square foot was obtained from stock plants grown in 3-qt containers, indicating that the smaller containers allow for the most efficient use of space when growing mojave sage stock plants for 4 to 6 months. The rooting of vegetative cuttings was successful (88% to 100% of cuttings rooted after 4 weeks under mist) for all treatment combinations.