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  • Author or Editor: Larry W. Grimes x
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Stock plants of six herbaceous species (Antirrhinum ×hybrida `Primrose with Vein' L., Chrysocephalum apiculatum `Golden Buttons', Diascia ×hybrida `Sunchimes Coral' Link & Otto, Lavendula dentata `Serenity' L., Osteospermum ×hybrida `Zulu' L., and Verbena ×hybrida `Lanai Bright Pink' L.) received nine different pinch treatments. Stock plants received a first pinch treatment at one of three pinch heights [low (L1), middle (M1), and high (H1)] followed by a second pinch at one of three pinch heights [low (L2), middle (M2), and high (H2)] in a 3 × 3 factorial arrangement. After the two pinches, cuttings were removed weekly from the stock plants. Cutting yield per stock plant increased as pinch height increased from L to H for both the first and second pinch for all species. A low first pinch followed by a low second pinch (L1L2) produced stock plants with the lowest cutting yield, while a high first pinch followed by a high second pinch (H1H2) produced the stock plants with the highest cutting yield for all species, e.g., the percentage increase in cutting yield was 133% for Antirrhinum, 98% for Chrysocephalum, 144% for Diascia, 80% for Lavendula, 250% for Osteospermum, and 44% for Verbena. This study suggests that pinch height during scaffold development of the stock plant is an important tool for increasing cutting production.

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Stock plants of four vegetatively propagated annual species (Argyranthemum frutescens `Comet Pink', Nemesia fruticans `Plum Sachet' Venten., Osteospermum fruticosum `Zulu' L., and Verbena ×hybrida `Lanai Bright Pink' L.) were grown with one (P), two (PP), or three (PPP) pinches during the scaffold development phase. The number of pinches applied to all four species affected the yield and distribution of cuttings produced over time. P began to produce cuttings first; however, the rate (number of cuttings per week) of cutting production was relatively low resulting in the fewest total cuttings produced by the end of the experiment. Cutting harvest from PPP started 3 to 6 weeks after cuttings were initially harvested from P. However, the rate of increase in cutting production was greater in PPP than P for all species, except Osteospermum, so the total cutting yield of PPP equaled P after 3 to 5 weeks of cutting production. The final cutting yield for PPP was 38%, 38%, 20%, and 8% higher than P for Argyranthemum, Nemesia, Osteospermum, and Verbena, respectively. PP produced 24%, 17%, and 21% more total cuttings than P for Argyranthemum, Nemesia, and Osteospermum, respectively, while Verbena displayed no significant difference. At the termination of the experiment, the weekly rate of cutting production increased 66.3%, 84.0%, and 30.5% as pinch number increased from P to PPP for Argyranthemum, Nemesia, and Verbena, respectively. This study demonstrates that the number of pinches performed on stock plants during scaffold development can have a significant impact on the timing, the weekly production rate, and cumulative yield of cuttings harvested.

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Poinsettia (Euphorbia pulcherrima Willd. Ex Klotzch) `Freedom Red' (FR), `Success Red' (SR), and `Winter Rose Dark Red' (WRDR) and pansy (Viola wittrockiana Gams.) `Colossus Yellow Blotch' (CYB), `Delta Pure Yellow' (DPY), and `Majestic Giants Purple' (MGP) were treated with 14 different tank mix combinations of daminozide and chlormequat ranging from 0 to 4500 mg·L-1 daminozide and 0 to 1500 mg·L-1 chlormequat. The tank mix treatments reduced stem elongation for all three poinsettia cultivars. Total bract area of FR and canopy bract diameter of WRDR decreased linearly as daminozide or chlormequat concentration increased, while bract area of SR was affected by daminozide alone. Anthesis was not delayed by any of the plant growth regulator (PGR) applications. For pansies, growth responses to the PGR treatments varied with cultivar. CYB growth was affected by daminozide alone, DPY growth was affected by daminozide and/or chlormequat, while MGP growth was relatively insensitive to both PGRs. Time to flower of pansy was not affected by the PGR applications. Chemical names used: 2-chloroethyl N,N,N-trimethylammonium chloride (chlormequat chloride); butanedioic acid mono (2,2-dimethylhydrazide) (daminozide).

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