Freedom Red Research Articles

Identifying the Temporal Sensitivity of Poinsettia Flowering to High Temperatures

The objective of this study was to identify the specific weeks and night lengths when poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch) flowering is most sensitive to high temperatures. One experiment was conducted in greenhouses under natural daylength (ND) conditions at lat. 34.7°N starting on 4 Sep, and a second experiment was conducted in growth chambers with an initial night length (NL) of 11 hours 01 minutes that was increased by 2 min/d to simulate ND conditions through September and October. Each week, one group of plants was moved from a moderate-temperature environment [22 °C average daily temperature (ADT)] to a high-temperature environment 28 °C ADT. Each group of plants spent 1 week in the high-temperature environment before returning to the moderate-temperature environment. The temperature treatments lasted for 7 or 8 weeks for the growth chamber and greenhouse studies, respectively. Additional groups of plants were kept in either the moderate- or high-temperature environment for the entire treatment period as controls. Four cultivars were used in the greenhouse study: Advent Red, Freedom Red, Prestige Red, and Tikal Red; only Prestige Red was used in the growth chamber study. Advent Red was identified as the most heat-tolerant cultivar followed by Tikal Red, Freedom Red, and Prestige Red. ‘Advent Red’s’ period of sensitivity to high temperatures ranged from 4 Sep to 1 Oct. ‘Tikal Red’s’ period of sensitivity to high temperature ranged from 11 Sep to 8 Oct. ‘Freedom Red’ had a longer period of high-temperature sensitivity: from 11 Sep to 22 Oct. ‘Prestige Red’ had the longest period of sensitivity to high temperatures encompassing 4 Sep to 29 Oct, and 11 hours 01 minute to 12 hours 37 minutes NL for the greenhouse and growth chamber studies, respectively. Within periods of sensitivity to high temperatures, time to visible bud and anthesis were most affected by high temperatures in earlier weeks, and final bract color development and time to first bract color were more affected by high temperatures during the latter weeks. As cultivars varied in their duration of sensitivity to high temperatures, duration, as well as magnitude of response to high temperature, should be considered in future breeding projects.

Reducing Substrate Moisture Content during Greenhouse Production of Poinsettia Improves Postproduction Quality and Economic Value

The objective was to determine the effect of substrate moisture content (SMC) during poinsettia (Euphorbia pulcherrima) greenhouse production on plant quality, postproduction longevity, and economic value. Two experiments were conducted, one in 2016 with ‘Freedom Red’ and the other in 2017 with ‘Christmas Eve Red’. Treatments included two SMC levels (20% or 40%) applied in four timing of application combinations. Total production (TP) time was 14 (2016) or 12 (2017) weeks in which vegetative production (VP) occurred from week 33 (2016) or 35 (2017) to week 39 and reproductive production (RP) continued from week 40 to 47. The four timing of application treatments were 40/40 = TP at 40% SMC; 20/40 = VP at 20% + RP at 40%; 40/20 = VP at 40% + RP at 20%; 20/20 = TP at 20% SMC. After simulated shipping in the dark, plants were evaluated in a simulated retail environment with two packaging treatments: no sleeve covering or plastic perforated plant sleeves covering container and plant. At the end of greenhouse production, plants grown in 20% SMC during RP (20/20 and 40/20) had shorter bract internode length, stem length, and smaller growth index (GI), decreased shoot and root dry weight (DW), and bract and leaf surface area compared with those in 40% SMC during RP (40/40 and 20/40). Photosynthetic rate was higher when plants were watered at 40% SMC regardless of production stage compared with those in 20% SMC. Leaf thickness, petiole thickness, total bract and leaf number were unaffected by SMC treatments. Plants in 20% SMC during RP (20/20 or 40/20) had earlier bract coloring despite days to anthesis being the same for all SMC treatments. Compared with 40/40, 40/20, and 20/20 could save 44.2% or 43.6%, respectively, irrigation and fertilizer usage, and 39.1% and 47.8%, respectively, labor time. During postharvest, ethylene concentration was unaffected by packaging method. Sleeved plants, regardless of SMC treatment, received lower light intensity in the middle of the plant canopy, causing plants to have lower total leaf number due to abscission and SPAD reading at the end of postproduction. The 40/40 treatment abscised more bracts during five weeks (in 2016) of postproduction and with no sleeve had higher number of bracts with bract edge burn (BEB). In summary, reducing SMC to 20% during TP or RP reduced water usage during production and produced more compact plants with increased postproduction quality.

Influence of different levels of Ethephon on the growth and flowering of Euphorbia pulcherrima var. 'Freedom Red'.

This study was carried out at the experimental farm of Horticultural Department, Faculty of Agriculture., Al-Azhar University, Nasr City, Cairo, Egypt, during the two successive seasons of 2014/2015 and 2015/2016. The effect of ethephon at different the rate on Euphorbia pulcherrima var. 'Freedom Red' plants was studied to dwarf their height aiming to produce more compact potted plants. The maximum dwarfing was obtained with ethephon at 1000 ppm, which recorded average height of 22.95 and 23.95 cm/plants for November and December periods, respectively. Furthermore, applying plants with the same ethephon level gave the highest the number of branches, followed by 500 ppm ethephon compared to the other concentrations or the untreated plants (control). The maximum leaves the number was obtained with ethephon treatment of 500 ppm. All concentrations of ethephon delayed the first bract color timing, whereas ethephon treatments at 1000 ppm increased the number of days until the first bract coloring more than other treatments of 300 or 500 ppm and the control. The biggest bracts canopy was observed in the control plants, since it recorded 57.61 cm/canopy. On the other hand, the higher level of ethephon (1000 ppm) led to the lowest bracts canopy.

Controlling Poinsettia (Euphorbia pulcherrima Will.) Height with Growth Retardant Application in West Java, Indonesia

A study was conducted to evaluate the effects of the growth retardant Cycocel application in the growth and development of poinsettia (Euphorbia pulcherrima) ‘Freedom Red’. Cycocel was applied by spraying plant shoots at the concentrations of 1000, 1500, 2000, 2500 ppm. The increase in cycocel concentrations reduced plant height, leaf size, internodal length, plant spread and the number of flowering plants. All cycocel concentrations resulted in an ideal potted plant height. The optimum spray concentration of Cycocel used to obtain compact and uniformly flowering plants under tropical West Java environment was 1000 ppm.

Use of nondestructive sensors to assess nitrogen status in potted poinsettia (Euphorbia pulcherrima L. (Willd. ex Klotzsch)) production

Utilizing precision farming techniques in a greenhouse setting to manage plant site-specific nitrogen (N) needs can help to prevent N deficiency, increase final plant quality, reduce cost of excessive fertilizer, and prevent N runoff. Optical sensors are a fast and nondestructive approach to estimate plant chlorophyll content by measuring the reflectance or absorbance of the green leaves. The objective of this study was to test the reliability of normalized difference vegetative index (NDVI) values calculated by the GreenSeeker™ hand held sensor as an indirect indicator of poinsettia (Euphorbia pulcherrima L. (Willd. ex Klotzsch) N status, and compare the sensors performance to other optical sensors on the market. The second objective of the study was to investigate if plant quality is improved by correcting N fertilizer application during production based on the sensor readings. The experiment was conducted in fall 2013. Poinsettia ‘Prestige Red’ and ‘Freedom Red’ pots were supplemented with 0, 5, 10, 15, and 20g of 15N-9P-12K controlled release fertilizer (CRF). Soil and plant analysis development (SPAD) chlorophyll meter, GreenSeeker™ NDVI sensor, and atLEAF meter readings were recorded for four consecutive weeks. Readings and visual qualities differences were monitored for significant separation between the different rates. At 40 days after planting (DAP), based on visual qualities differences, half of the deficient treatments were supplemented with extra fertilizer for treatment correction. All pots were completely randomized. All sensors values were compared to actual leaf N concentration to determine efficiency. Plants were assessed at the end of commercial production period by recording final height, final width, number of bracts, length of bract, dry weight, and salability. The GreenSeeker™ NDVI sensor correlated well with actual leaf N concentration during the vegetative phase of poinsettia production. As for the overall production period, SPAD and atLEAF meters showed an advantage with greater correlation to actual leaf N concentration. The GreenSeeker™ readings were less correlated with leaf N concentration at early stages of establishment due to plants small size and background noise, as well as at later stages of establishment due to anthesis. Poinsettia ‘Freedom Red’ responded better to treatment correction than ‘Prestige Red’. The correction treatments showed greater results for plant growth in the treatment correction 5 (+5g) compared to treatment correction 0 (+10g), and as good as the 10g treatment, indicating that the correction treatment could be used to correct deficiencies during production.

Influence of growth retardant on growth and development of Euphorbia pulcherrima Willd. ex Klotzsch

This study was undertaken to evaluate the influence of single foliar flurprimidol treatment on morphology and transpiration of ‘Roman’ and ‘Freedom Red’ poinsettias. The growth retardant flurprimidol (Topflor 015 SL) was applied once as a foliar spray at concentrations of 5, 10 or 15 mg × dm<sup>-3 </sup>when lateral shoots were about 5 cm in length. Single foliar flurprimidol treatment was sufficient to inhibit stem elongation of both poinsettia cultivars. The degree of growth inhibition depended on cultivar and growth retardant concentration. As compared to the control, the shoots of flurprimidol treated ‘Roman’ and ‘Freedom Red’ plants were up to 44% and 37% shorter, respectively. The desirable plant heights for ‘Roman’ and ‘Freedom Red’ poinsettias were obtained with flurprimidol at concentrations of 5 and 10 mg × dm<sup>-3</sup>, respectively. The shoots of flurprimidol sprayed poinsettia were also more rigid and aligned relative to each other and thus the bracts on the plant were placed on the same level. The diameters of growth retardant treated poinsettias were up to 13% narrower. The leaf areas, petiole lengths, fresh and dry weights of ‘Roman’ and ‘Freedom Red’ poinsettias treated with flurprimidol were substantially smaller as compared to the control. The bract diameters of both poinsettia cultivars were only slightly affected by growth retardant application. Plants exposed to flurprimidol had also intensified green leaf pigmentation. There was almost no abscission of the oldest leaves in the low portions of growth retardant treated plants, compared to those of the control ones. Flurprimidol had no effect on transpiration rate per unit leaf area and stomatal conductance in both poinsettia cultivars. No phytotoxicity was observed in flurprimidol treated plants. Chemical name used: α-(1-methylethyl)-α-[4-(trifluromethoxy)phenyl]-5-pyrimidinemethanol (flurprimidol).

Effects of Daily Light Integral and Canopy Density on Shoot Growth and Development in a Poinsettia (Euphorbia pulcherrima Willd. ex. Klotsch) Stock Plant Canopy

Poinsettia stock plants consist of a dense canopy of competing shoots, and the growth and development of these individual shoots have not been previously quantified. The effects of air temperature, daily light integral (DLI), and canopy density (CD) were investigated on poinsettia (Euphorbia pulcherrima Willd. ex. Klotsch) ‘Freedom Red’ shoot development in a stock plant canopy. Plants were grown at two constant temperatures (20.3 or 25.7 °C), five CD (43, 86, 129, 172, or 215 shoots/m2), and three DLI treatments (2.6, 4.4, or 7.7 mol·m−2.d−1 for the September planting and 4.0, 6.0, or 10.6 mol·m−2.d−1 for the January planting). Shoot position at the final data collection was used to assign shoots to different levels within the canopy; Level 1 = the four highest shoots, Level 2 = the next four highest shoots, and so forth for Levels 3, 4, and 5. Temperature did not significantly affect leaf unfolding rate (LUR), shoot fresh mass (FM), or shoot caliper, whereas DLI and CD affected shoot growth and development. LUR and FM increased as DLI increased from 2.6 to 10.6 mol·m−2.d−1, whereas LUR and FM decreased on the uppermost shoots in the canopy, e.g., Level 1 shoots, as CD increased from 43 to 129 shoots/m2. Therefore, higher CD required higher DLI to achieve similar LUR and FM. Shoot caliper on Level 1 shoots increased from 6.3 to 7.4 mm as CD decreased from 129 to 43 shoots/m2; and shoot caliper increased from 5.8 to 7.6 mm as DLI increased from 4.0 to 10.6 mol·m−2.d−1. The DLI environment needs to be managed to accommodate greater CD, to sustain growth and development of individual shoots within the canopy of poinsettia stock plants.

Floriculture Sustainability Research Coalition: Bringing the Latest Sustainability Research to the Industry

C onsumer interest in environmentally friendly products has increased greenhouse growers’ interest in sustainable production techniques. It is estimated that consumers would spend up to 15% more for sustainable floricultural products than conventionally produced products, and purchasers of herbaceous or floricultural plant products tend to be more eco-friendly than those who purchase woody plant materials (Behe et al., 2010; Hawkins et al., 2011). In 2008, the Floriculture Sustainability Research Coalition (FSRC) was formed to provide information regarding sustainable production techniques for growers. Forming a coalition has allowed the group to broaden our expertise to have a more meaningful impact on growers’ production practices. The FSRC began in 2008 at the National Floriculture Forum. Founding institutions include Purdue University, University of New Hampshire, Cornell University, and University of Maine. Our core purpose is to develop central sustainability themes for outreach and research programs that synergistically build on individual strengths to increase knowledge and create outreach materials that benefit our audience. Alone, it is difficult to have much of an impact on such a large topic. But, as a group, we could potentially have more impact—not only topically, but also regionally. Cornell University examines sustainable and organic fertilizer use and energy conservation, Purdue University provides expertise in sustainable lighting and energy conservation, University of New Hampshire specializes in nonchemical growth regulation and sustainable fertilizer use, and at University of Maine, research focuses on water conservation and organic substrates and fertilizers. Over the past 3 years, the FSRC has provided research-based information to help growers produce floricultural crops more sustainably. Recent initiatives have included exploring techniques for sustainably heating greenhouses, reducing plant stretch without the use of chemical growth retardants, and developing protocols for using organic fertilizers. Conserving energy is a priority for greenhouse growers throughout the United States. A survey of greenhouse growers indicates that 55% of growers are currently using energy conservation practices; an additional 8% would like to conserve energy (Dennis et al., 2010). Our group has published several articles on novel techniques to reduce energy. For example, Lopez and Krug (2009) reported that growing medium-vigor poinsettia (Euphorbia pulcherrima) cultivars at a temperature 10 F less than recommended (75/ 67 F day/night) does not reduce crop quality for some cultivars, including ‘Freedom Red’. But, this reduction in temperature set points in the fall would reduce fuel usage for greenhouse growers. At Cornell, bedding plants including ‘Safari Orange’ marigold (Tagetes patula), ‘Delta Formula Mix’ pansy (Viola ·wittrockiana), ‘Dreams Midnight’ petunia (Petunia ·hybrida), ‘Montego Mix’ snapdragon (Antirrhinum majus), and ‘Dreamland Mix’ zinnia (Zinnia elegans) were grown in an unheated high tunnel. Compared with the heated greenhouse environment, temperatures in the high tunnel were 5 F cooler (Table 1). Pansy plants did not finish significantly later in the high tunnel compared with the greenhouse; the other plants finished about 1 week later in the high tunnel. Part of our efforts in this area has focused on extension and outreach to support growers who are transitioning to more sustainable heating technologies. In trade publications, we have highlighted innovative growers who may inspire others by example (Burnett et al., 2010). Currently, Purdue University, in collaboration with Michigan State University, University of Arizona, and Rutgers University, isworkingonaU.S.Department of Agriculture (USDA) Specialty Crops Research Initiative grant to develop light-emitting diodes as supplemental and photoperiodic lighting for greenhouses. Another highlight of our work with sustainable production has focused on finding alternatives to chemical growth retardants. Our approach to reducing plant stretch without chemical growth retardants has been to recommend that growers adjust the greenhouse or plant environment. R. Lopez and B. Krug have represented our group to growers nationally and regionally. Some techniques we have successfully used include reducing water to reduce turgor in a controlled manner. Using new moisture sensors, plants may be grown in substrates that are maintained at constant moisture contents. So, they may be grown in relatively dry substrates (volumetric water content = 15% to 25% in a peatlite mix) without risking plant damage. This may reduce plant height, but controlled drought also reduces branching (Burnett and van Iersel, 2008). One straightforward way to reduce elongation is simply to grow plants at the appropriate light level. This will reduce plant stretch by minimizing shading, particularly from neighboring plants.

Manipulation of Light Environment to Produce High-quality Poinsettia Plants

The phytochromes, a family of photoreceptors that maximally absorb red (R) and far-red (FR) light, play an important role in defining the architecture of the plant and consequently its value in the market. In this work, we evaluated the manipulation of light quality as an alternative to the use of plant growth regulators (PGRs) to produce poinsettia plants (Euphorbia pulcherrima Willd. ex Klotzsch) without affecting commercial quality parameters. ‘Freedom Red’ poinsettia plants were cultivated in two light environments characterized by different R/FR ratios in combination with or without one application of PGR. We used a photoselective film that significantly reduced the FR component of the light and a transparent film to obtain high and low R/FR ratios (5.7 and 1.1, respectively). Plants cultivated under a high R/FR ratio were shorter and more compact than those grown under transparent film. Other quality characters like bract and leaf area, dry weight, stem diameter, number of lateral branches, and plant width did not differ significantly between light treatments. Flowering time was slightly delayed in plants grown under a high R/FR ratio compared with those cultivated under the control treatment. Additive effects were detected between light quality and PGR factors indicating that light quality manipulation is an alternative strategy to reduce or to replace the use of PGRs in commercial production systems that usually require several PGR applications.

Suppressing Sting Nematodes with Brassica sp., Poinsettia, and Spotted Spurge Extracts

With synthetic nematicide options becoming limited, two studies were initiated to investigate the usefulness of selective botanical extracts for the suppression of sting (Belonolaimus longicaudatus Rau) nematodes. Plant materials were from greenhouse‐grown mature specimens of spotted spurge (Chamaesyce maculata L. Small); poinsettia (Euphorbia pulcherima Willd. ‘Freedom Red’); lantana (Lantana camara var. hybrida); mature, field‐grown tall lettuce (Lactuca canadensis L.); and goldenrod (Solidago altissima L. var. scabra), plus a seed meal extract from Brassica juncea ‘Pacific Gold’ (BSM). Nematodes were exposed to 1.2‐mL extract of either shoot or roots of each plant species. Nematode mortality counts were made daily for 4 d. In Study 1, effects of botanical extracts on nematode mortality were evaluated when applied directly to laboratory‐controlled sting nematode populations in test tubes. Root extracts of spurge, poinsettia, and lantana provided 69, 70, and 57% mortality, respectively, by 96 h while goldenrod and tall lettuce root extracts and the untreated provided 0% mortality. Shoot portions of poinsettia and spurge provided 95 to 98% mortality while goldenrod, tall lettuce, and lantana shoot extracts had 64, 40, and 25% mortality, respectively. Greenhouse studies evaluated the most successful laboratory extracts in a soil environment and included poinsettia shoot extracts and BSM. Poinsettia shoot extracts with irrigation provided 70% control compared with the untreated pots while poinsettia nonirrigated provided 73% control. Brassica sp. seed meal with irrigation provided 92% control while BSM nonirrigated provided 99.5% control. Brassica sp. seed meal, poinsettia, and spurge shoot extracts showed most promise as possible biocontrol agents of sting nematodes.

(309) Consumer Survey Reveals Poinsettia Cultivar Preferences for 2005

Twenty-one cultivars of poinsettia [Euphorbia pulcherrima Willd. Ex Klotzsch] were evaluated by respondents who voluntarily completed a paper survey (n=293) at TSU. Rooted cuttings from five major U.S. suppliers were potted and grown during the preceding 4 months according to standard industry practices. Cultivars were displayed without their names for the survey, and respondents were asked to rate each cultivar on a Likert-type scale, where 1=strongly dislike and 5=strongly like. The top eight rated cultivars (mean > 3.9) were all traditional red forms, which included the new cultivar `Red Dragon', followed in descending preference by `Christmas Spirit', `Freedom Red', `Cortez Electric Fire', `Prestige Red', `Premium Red', `Novia Red', and `Candlelight'. For each cultivar, the price respondents indicated they would be willing to pay was highly correlated with the Likert-type scale score. When asked about purchases in the prior year, 89% of respondents bought at least one red poinsettia. Retail outlets and prices paid varied among respondents. Color was by far the most popular criterion respondents used to determine whether they like or dislike a cultivar, followed by foliage and price. Consistent with recent trends for value-added products, consumers indicated that they would be willing to pay significantly more for a purple-painted plant with glitter than for a white-flowered plant that was otherwise of comparable quality. These results suggest that, while red poinsettias continue to dominate the poinsettia market, niche markets exist for unique flower and foliage traits created through breeding and through enhancements such as paint and glitter.

(67) Survey at Poinsettia Open House Reveals Preferred Cultivars

A high quality finished plant from each of 22 cultivars was displayed at a poinsettia [Euphorbia pulcherrima Willd. ex Klotzsch] open house at Tennessee State University in Dec. 2004. The cultivars represented the range of flower colors, flower traits, and plant vigor available through the major suppliers Dummen USA, Ecke, Fischer, and Oglevee. Attendees of the open house completed a written survey (n = 101) in which they were asked to rate their cultivar preferences. Cultivars (identified only by an alphabetic letter) were rated by respondents on a Likert-type scale (1 = strongly dislike to 5 = strongly like). Highly rated cultivars (mean ≥4) included `Freedom Red', `Premium Red', `Nutcracker White', `Early Orion', `Cortez Electric Fire', and the new cultivars `Visions of Grandeur' and `Kris Krinkle'. Cultivars were also rated on the price range potential consumers were willing to pay. Respondents were willing to pay the most to purchase `Visions of Grandeur', which is a vigorous cultivar with large, pillowy, peach-colored bracts. Overall, traditional red cultivars and large, non-red cultivars were preferred. Most of the respondents indicated that they purchased red plants, and color was the most important selection criterion. Results suggest that although most consumers prefer traditional red cultivars, women prefer some alternative inflorescence colors and unique bract shapes more than men.

EFFECT OF 1-MCP ON THE POSTHARVEST PERFORMANCE OF UN-ROOTED POINSETTIA CUTTINGS

Un-rooted poinsettia (Euphorbia pulcherrima 'Eckespoint Freedom Red') cuttings were placed into plastic bags at 10, 18 or 26°C for 72 h. 1-methylcyclopropene (1-MCP) sachets were placed into one half of the bags at each incubation temperature, while the other half of the bags served as a controls. Ethylene concentrations inside the bags were monitored at 12, 24, 48 and 72 h. The cuttings were placed on a propagation bench following 72 h of storage, and leaf abscission was recorded after 4 days in propagation. Leaf abscission increased in the control packages as temperature increased from 10 to 26°C, while 1-MCP reduced leaf abscission at 18 and 26°C. Thus, at 26°C 0.8 or 0.15 abscised leaves per cutting were monitored for control or 1-MCP-treated cuttings, respectively. The ethylene concentration measured at 48 h in the control packages increased from 0 to 0.5 ppm as the temperature increased from 10 to 26°C, while in the packages with 1-MCP it increased from 0 to 2.1 ppm with increasing temperature. Thus, while no ethylene was produced by the cuttings at 10°C, with or without 1-MCP, the presence of 1-MCP resulted in accumulation of significantly higher ethylene concentrations in the packages stored at 18 or 26°C. Our results suggest that 1-MCP sachets placed in packages of un-rooted poinsettia cuttings provide a viable means for reducing their leaf abscission following shipment of 72 h at non-optimal temperatures, in spite of the high ethylene levels accumulated in the packages under these conditions. However, these higher ethylene concentrations induced by the 1-MCP treatment may cause a concern if shipments are delayed and the efficacy of the 1-MCP decreases over that time.

Establishment of Calibration Curves for Comparing Pour-through and Saturated Media Extract Nutrient Values

Most commercial and university substrate testing laboratories' recommended floriculture nutritional values are based on the saturated media extract (SME) method. With the recent gain in popularity of pour-through nutritional monitoring, alternative recommended values are needed for nutrient analyses based on pour-through extracts. Pour-through nutritional values were compared to the SME values to develop calibration curves and recommended nutritional values. Euphorbia pulcherrima `Freedom Red' Willd. ex Klotzch. were grown for two consecutive growing seasons in 16.5 cm plastic pots with Fafard 4 P root substrate and fertigated with 200, 300, or 400 mg·L-1 N from a 13N-0.88P-10.8K fertilizer. Linear relationships existed and inverse calibration curves for pour-through and SME comparisons were developed for (r2): EC (0.98), NO3- (0.98), P (0.97 to 0.99), K (0.99), Ca (0.94 to 0.97), and Mg (0.91). In addition, recommended pour-through substrate value ranges were developed for comparison with SME values. The established calibration curves and pour-through substrate value ranges will allow substrate-testing laboratories to make nutritional recommendations based on pour-through extractions.

The Effect of Daminozide and Chlormequat on the Growth and Flowering of Poinsettia and Pansy

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).

Expression of induced systemic resistance in poinsettia cuttings against Rhizoctonia stem rot by treatment of stock plants with binucleate Rhizoctonia

Abstract Three cultivars of poinsettia (V14 Glory, Freedom Red, and Angelica White) were evaluated for induction of host resistance to Rhizoctonia stem rot in cuttings acquired from stock plants treated with binucleate Rhizoctonia (BNR) in a Pesta formulation. Resistance to stem rot in cuttings of V14 Glory was induced within 7 days of treatment with BNR while Freedom Red and Angelica White did not express resistance until 10 or more days after application of BNR to stock plants. None of the cultivars expressed resistance to stem rot when cuttings were taken from stock plants that were treated with BNR for only 3 or 5 days before propagation. Population dynamics of BNR on poinsettia root tissue were consistent with the expression of induced resistance. A dramatic increase of root colonization by BNR was observed in all cultivars between day 5 and 7. The integrated use of both BNR and Burkholderia cepacia, previously characterized as a stem rot control agent during poinsettia propagation, was evaluated to test for enhanced resistance against stem rot. No additive effect on stem rot control was observed when cuttings taken from stock plants treated with BNR were propagated in rooting strips treated with B. cepacia compared to cuttings propagated in root strips treated with B. cepacia alone. Our results may be the first to demonstrate induced systemic resistance by BNR fungi during vegetation propagation where the biocontrol agent applied to roots of a stock plant was able to protect cuttings from Rhizoctonia solani during propagation.

LEAF ANATOMICAL AND NUTRIENT CONCENTRATION RESPONSES TO NITROGEN AND SULFUR APPLICATIONS IN POINSETTIA

ABSTRACT Today the many varieties of poinsettia available for production-dates printpubdate="07/01/2002" are typically designated as one of two types: dark leaf vs. green leaf/light leaf types. Research has shown that dark leaf varieties require less fertilizer than green leaf types. The objectives of this research were to evaluate the effect of varying nitrogen (N) and sulfur (S) fertilizer applications on leaf anatomy, essential nutrient elements, and the growth and development of a dark leaf variety of poinsettia. Vegetative “Freedom Red” poinsettias were grown in a soilless mix following a typical production-dates printpubdate="07/01/2002" schedule except for fertilization. Plants received N at 50, 100, 200, or 275 mg L−1 in combination with S at 0, 12.5, or 25 mg L−1. Visual observations of plants indicated that “Freedom Red” poinsettia responded differently to various application rates of N and S. Plants inferior in size, form, and color were produced when S was applied at rates of 0 mg L−1 in combination with any level of N and 12.5 or 25 mg L−1 S at 50 or 100 mg L−1 N. Specific N-S ratios of applied nutrients were not a reliable predictor of visual quality. Anatomically, “Freedom Red” leaves were typical of poinsettia, consisting of a single-layer papillate epidermis and a single row of palisade cells. There appeared to be one notable difference among treatment extremes: in treatments receiving 50 mg L−1 N, the length of palisade cells was nonuniform from one cell to the next. Leaf tissue analysis indicated that most of the essential elements were present in sufficient amounts. Nitrogen and S concentrations ranged from below critical level to normal range in direct response to the quantity of each nutrient applied. The application of N affected boron, copper, and chlorine while S had an effect on molybdenum.

Recycled Newspaper Reduces Nutrient Leaching from Container-grown Poinsettia

Two experiments were conducted to evaluate recycled newspaper products as nutrient filters in the bottom of containers. In Expt. 1 with poinsettia, Euphorbia pulcherrima Willd. ex Klotzsch `Glory', three paper products were evaluated: ground paper, paper crumble, and paper pellets; each placed 2 or 3 cm deep in the bottom of containers, so that drainage holes were covered. Leachate samples were collected at the first irrigation after each liquid fertilization. Nitrate (NO3--N) and ammonium (NH4+-N) leachate concentrations were reduced up to 84% with recycled paper pellets, compared to the control (no paper). Recycled paper retained up to 732 mg of nitrogen (N) per container (paper pellets 3 cm deep). Shoot dry weight was reduced with paper pellets but was not affected by ground paper or paper crumble. In Expt. 2, `Freedom Red' poinsettias were grown with either single weekly applications of 500 mg·L-1 N from Peter's 20N-4.3P-16.6K, or 200 mg·L-1 N at each irrigation (2 or 3 times a week, as needed). Recycled paper treatments included paper crumble or paper pellets placed 2.5 cm deep in the bottom of containers, and a control without paper. Leachate NO3--N and NH4+-N concentrations were reduced up to 100% and 94%, respectively, 6 days after planting (DAP), and up to 57% and 50%, respectively, 25 DAP with paper crumble compared to nonpaper control. Paper pellets in the bottom of containers retained up to 776 mg N per container. Poinsettia shoot dry weight was lowest with paper pellets in the bottom of containers and continuous fertilization.

COMPARISON OF THREE CONTROLLED-RELEASE NITROGEN FERTILIZERS IN GREENHOUSE CROP PRODUCTION

Controlled-release nitrogen fertilizers allow growers to reduce nitrogen loss from leaching in comparison to soluble formulations. Plant growth and nitrogen leaching during greenhouse production of Begonia × semperflorens-cultorum Hort. cv. “Brandy” (Begonia), Euphorbia pulcherrima Willd. ex Klotzch cv. “Freedom Red” (Poinsettia), Ficus benjamina L., and Nephrolepis exaltata (L.) Schott cv. “Bostoniensis” (Boston Fern) were evaluated for eight weeks using three commercial controlled-release nitrogen fertilizers in combination with phosphorus and potassium sources to maintain a 3 : 2:1 NPK ratio. Mini Polymer Coated Urea (MPCU) 41-0-0, Trikote 42-0-0, and Regalite Nitroform (RN) 38-0-0 were incorporated into the substrate at rates of 0.9 kg nitrogen (N) m−3 and 1.5 kg N m−3 prior to potting. Total soluble salts in the leachates reflected the initial leaching of salts from the substrate, some increase or maintenance of salt levels through the third week, and lower levels from the fourth through eighth weeks. The high and low rates of Trikote and the high rate of MPCU provided acceptable levels of NH4 + for production purposes through the fourth or fifth week, the low rate of MPCU provided low levels through the third week and minimal levels thereafter, while both levels of RN showed progressive decreases from the outset. NO3 − levels varied within treatments during the eight-week period, with levels suitable for production observed during the trial with MPCU and Trikote, and declining to low levels with RN. Growth indices were similar among treatments, with the exceptions of Begonia and Poinsettia, which were larger with a low rate of RN 40 days after potting (DAP). Begonia was also larger with a low rate of Trikote 40 DAP. Shoot fresh weights (SFW) of Begonia and Poinsettia were higher with a low rate of Trikote than with MPCU or RN 40 DAP, and higher for Poinsettia with low rates of both MPCU and Trikote compared to RN 57 DAP. SFW and shoot dry weights (SDW) were similar among treatments with Boston Fern and Ficus benjamina.

Earthworm Castings as a Substrate for Poinsettia Production

Experiments were conducted to evaluate earthworm castings (vermicompost) as a substrate for poinsettia (Euphorbia pulcherrima Willd.) `Freedom Red' production. Vermicomposts produced from sheep, cattle, or horse manures were mixed at different ratios with 70 peatmoss: 30 perlite (v/v) to create 13 substrates. Chemical and physical properties were measured on all substrates used. Growth index, foliar and bract area, and dry weight were greater on plants grown in substrates with castings from sheep or cattle manure. These castings had greater initial nutrient content than the castings from horse manure. Mixtures of castings and peat produced better plant responses than castings alone. Better plant responses were sometimes associated with values outside the recommended pH and electrical conductivity levels for poinsettia production. The highest values obtained for growth index, foliar and bract area, dry weight, and root development were produced in the substrates with moderate pore space or water holding capacity. Substrates with greater air space produced plants with greater dry weight and root development than substrates with less air space. The highest quality plants were grown in substrates with 25% castings from sheep or cattle manures.