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  • Author or Editor: John. E. Erwin x
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Five cuttings from different node positions on stock plants were taken from each of 3 Clematis cultivars (Jackmani, Contesse de Bouchard, and Gypsy Queen) and Clematis purpurea plena elegans. Actively growing plants with 5 nodes were acquired. Node number increased from 1 at the base of the plant to 5 at the tip of the plant. Cuttings were treated with or without 0.1% IBA (indole-3-butyric acid) and placed in 1 of 5 different media: 100% washed sand (WS), 50% washed sand and 50% sphagnum peat (WP), 50% sphagnum peat and 50% perlite (SP), 100%) perlite (PT), or 50% sphagnum peat plus 25% perlite plus 25% vermiculite (PV). Rooting date, primary and secondary root number, and root dry weight were collected after 8 weeks. `Gypsy Queen' showed the earliest rooting with the greatest root development. Jackmani showed the worst rooting. Media WS and PT showed the best rooting whereas WP and SP showed the worst. Cuttings taken from the first 3 nodes rooted the best. As node position increased root number and dry weight decreased and time to root increased. Application of IBA had no significant effect on time to root or degree of rooting.

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A phone survey was conducted to assess the total impact of the floriculture industry on the Minnesota economy. Data were collected from wholesale growers, garden center retailers, chain stores, and florists. Information was gathered on `hard good' sales associated with greenhouse produced plants as well as plant sales. In addition, data on labor and salaries associated with the production, distribution, and retailing of plants and goods associated with the floriculture industry was collected. This data will be provided to local flower growers organizations to enable these groups to actively lobby for their concerns within the state.

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Lypcopersicum esculentum cv `Money Maker' seeds were germinated at constant 20C. Three days after germination seedlings were randomly divided into 3 groups and placed into 3 growth chambers maintained at 23/17, 20/20, or 17/23C (day/night temperature) (DT/NT). Irradiance and photoperiod were maintained at 250 μmol s-1 m-2 and 12 hrs, respectively. At the 2 leaf stage, plants in each chamber were divided into 3 groups of 3 plants each to receive a growth regulator treatment. Growth regulator treatments consisted of spray applications of either ancymidol (52ppm), GA3 (12ppm), or water applied every 3 days for 21 days. Measurements were taken on internode length and chlorophyll content after 21 days. Internode length increased as the difference (DIF) between DT and NT increased (DT-NT). Exogenous applications of GA3 overcame inhibition of stem elongation resulting from a -DIF environment. Application of ancymidol did not significantly decrease stem elongation in a -DIF environment. Temperature regime had a significant impact on chlorophyll content per mg dry weight. In contrast, growth regulator applications had a significant impact on chlorophyll content cm-2. There was no significant impact of either temperature regime or growth regulator treatment on the chlorophyll a/b ratio.

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The interaction between day/night temperature (DT/NT) and irradiance during the photoperiod prior to the inductive night on Pharbitis nil (L.) cv. Violet flower induction was studied. Plants exposed to 12 or 18 °C NT did not flower regardless of DT. When NT was 24 or 30 °C, percent flowering plants increased progressively as DT increased from 12 to 30 °C. Percent flowering plants and total flower bud number per plant was greatest when seedlings were induced with a 24 or 30 °C DT/30 °C NT regime. DT/NT did not affect the node number to first flower. Irradiance did not affect flowering. Temperature effects on P. nil flowering could be described as a function of average daily temperature, where flowering increased as temperature rose from 22 to 30 °C.

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Rose plants (cvs `Royalty' and `Lovely Girl') in an established canopy were cut back to node 1, 3, 5, 7, 9, 11, or 13 from the base of the stem at harvest. Harvest was defined as the reflexing of the outermost petal. Most rose stems were composed of 13 nodes, therefore, pruning to the 13th node involved removing the flower only. Three leaf removal techniques were evaluated: 1) no leaf removal, 2) removing the node leaf only, or 3) removing all leaves on the stem. Total break number increased as the node position which stems were cut back to increased. For instance, break number increased on `Lovely Girl' from 1.8 to 2.6 breaks as node position increased from 1 to 13. The number of lateral breaks which developed into marketable flowers also increased as the node position which stems were cut back to increased. `Lovely Girl' flower number increased from 0 to 2.6 flowers per stem as node position increased from 1 to 13. Leaf removal reduced the number of marketable flowering shoots. For instance, flowering shoots decreased from 2.6 to 1.4 per stem on stems cut at the 13th node following removal of all leaves on that stem. `Royalty' had more lateral breaks than `Lovely Girl' but also had more non-flowering lateral breaks following pruning. Commercial implications of this research will be discussed.

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Our objectives were to assess the efficacy of various plant growth regulators (PGRs) on stem elongation and branching of 11 kalanchoe (Kalanchoe) species with ornamental characteristics: beauvard’s widow’s-thrill (K. beauvardii), K. glaucescens, lavender scallops or red-leaved kalanchoe (K. fedtschenkoi), K. longiflora, chandelier plant (K. manginii), marnier’s kalanchoe (K. marnieriana), K. millotii, flower dust plant (K. pumila), K. rosei, common kalanchoe or nentabos (K. rotundifolia), and K. streptantha. Foliar spray applications of deionized water, ancymidol (15−60 ppm), benzyladenine (75−300 ppm), chlormequat chloride (750−3000 ppm), daminozide (1250−5000 ppm), ethephon (250−1000 ppm), paclobutrazol (10−40 ppm), or uniconazole (5−20 ppm) were applied 2 weeks after plants were pinched. Stem length at the time of application and 4 weeks after applications and branch number were recorded. While effective chemicals and concentrations varied widely among species, paclobutrazol and uniconazole were identified as providing broad efficacy with respect to inhibition of stem elongation across all 11 species in this study. Additionally, benzyladenine and ethephon increased the number of branches for several species.

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Day (DT) and night temperatures (NT) influenced Lilium longiflorum Thunb. `Nellie White' stem elongation and development rate from the visible bud stage (VB) until anthesis. Plant height increase after VB was a function of the difference (DIF) between DT and NT (DT-NT). Plant height increased 90% as DIF increased from - 16 to 16C. A cubic model described bud development rate as a function of temperature from 14 to 30C. A linear model adequately described bud development rate as a function of average daily temperature from 14 to 21C. Based on the linear model, bud development rate increased 0.05 per day for each 1C increase in average daily temperature. The base temperature for bud development, i.e., the temperature at which bud development rate was 0, was calculated as 3.5C.

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Effect of media type, cultivar, and indole-3 butyric acid (IBA) application on Clematis spp. stem cutting rooting was studied. Cutting survival across all treatments was highest on `Comtesse de Bouchard' and `Gypsy Queen' cuttings and lowest on `Jackmani' cuttings. Cutting survival was greatest in perlite and lowest in peat-perlite-vermiculite. IBA application increased `Jackmani' cutting survival only. Time of root emergence was longest on `Jackmani' and least on `Gypsy Queen' cuttings across treatments. Root emergence occurred first in sand and perlite and last in peat-perlite across treatments. Root dry mass on cuttings from `Jackmani' and Clematis viticella purpurea plena elegens plants were unaffected by medium type. In contrast, root dry mass on `Comtesse de Bouchard' cuttings was highest in perlite and root dry mass on `Gypsy Queen' cuttings was highest in sand, perlite, and peat-perlite-vermiculite. The best media for propagating clematis were sand and perlite. Benefits to rooting cuttings in sand or perlite were similar, except rooting cuttings in perlite resulted in higher cutting root dry mass.

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The role of irradiance and/or ethylene in inducing mortality and self-branching disorders in Gerbera jamesonii Bolus. seedlings was studied. Seedling mortality increased from 8% to 57% when seed was covered with vermiculite than left uncovered during germination. Supplemental lighting for 30 days after germination decreased seedling mortality and decreased the time to visible bud compared to seed germinated under natural light only. In subsequent experiments, seeds were germinated and then seedlings were water logged or sprayed with ethephon (0.69, 3.45, or 17.25 mM) at four different stages of seedling development. Half of the ethephon-treated seedlings were sprayed with silver thiosulfate (STS). Seedling mortality was greatest after cotyledon expansion but before expansion of the first tree leaf. The highest ethephon concentration caused reduced seedling dry weight after 42 days. Applying STS did not overcome self-branching or meristem necrosis.

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Nephrolepis exaltata (L.) Schott `Dallas Jewel' plants were grown for 92 days under 16 day/night temperature (DT/NT) regimes and two photoperiods for a total of 32 environments. Temperatures ranged from 15 to 30 ± 1.5C. Photoperiod was either 9 hours (short days) or 9 hours plus a 4-hour night interruption (long days) using incandescent lamps. Photoperiod had no significant effect on either morphology or development rate. Frond length and leaflet count per frond were highly correlated with the average daily temperature (ADT). Frond length increased from 9.3 to 21.9 cm and leaflet count increased from 21 to 42 leaflets per frond as ADT increased from 15 to 30C. Solon count and frond orientation were highly correlated with the weighted difference (WDIF) between DT and NT. The weighted difference between DT and NT was equal to: (DT × photoperiod) - (NT × scotoperiod). The scotoperiod was inclusive of the night interruption. Stolon count increased as the weighted NT increased relative to the weighted DT, i.e., as WDIF decreased. In contrast, frond angle relative to the soil surface, i.e., frond orientation, increased as WDIF increased. Frond unfolding rate and total plant dry weight increased as temperature increased to ≈ 25C, then decreased.

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