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  • Author or Editor: Paul R. Fisher x
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Greenhouse propagation of unrooted plant cuttings is characterized by short container cell height and high irrigation frequency. These conditions can result in high moisture level and low air content in soilless container substrates (“substrates”), causing delayed growth of adventitious roots and favoring root disease. The objective of this study was to quantify and compare substrate water and air relations for three propagation substrates (peat, rockwool, and phenolic foam) that varied widely in physical characteristics using four methods: 1) evaporation method with a tensiometer, 2) frozen column method, 3) gravimetric analysis, and 4) X-ray computed tomography (CT) analysis. Moisture retention curves based on evaporation (1) and the frozen column (2) resulted in differences for peat, but similar curves for rockwool and foam. The frozen column method was simple and low cost, but was constrained by column height for peat, which had a higher water potential compared with the other two substrates. Substrate porosity analysis at container capacity by gravimetric or CT methods were similar for volumetric water and air content (VWC and VAC) in rockwool and foam, but differed for peat for VWC and VAC. Gravimetric analysis was simple, rapid, and low cost for whole-cell analysis, but CT further quantified spatial water and air relations within the cell and allowed visualization of complex water and air relations in an image. All substrates had high water content at container capacity ranging from 67% to 91% VWC with 5% to 11% VAC in the short propagation cells, emphasizing the need for careful irrigation management.

Open Access

The objectives were to 1) compare growth and yield of different ginger (Zingiber officinale) and turmeric (Curcuma longa) propagules grown under two photoperiods (Expt. 1); and 2) evaluate whether their growing season could be extended with night interruption lighting (NI) during the winter (Expt. 2). In Expt. 1, propagules included 1) micropropagated tissue culture (TC) transplants, 2) second-generation rhizomes harvested from TC transplants (2GR), and 3) seed rhizomes (R). Plants received natural short days (SDs) or NI providing a total photon flux density (TPFD) of 1.3 µmol·m−2·s−1. Providing NI increased number of new tillers or leaves per plant, rhizome yield (i.e., rhizome fresh weight), and dry mass partitioning to rhizomes in both species. There was no clear trend on SPAD index in response to photoperiod or propagative material. Although TC-derived plants produced more tillers or leaves per plant, 2GR ginger and R turmeric produced a higher rhizome yield. In Expt. 2, seed rhizomes of ginger and turmeric were grown under five treatments with different photoperiods and/or production periods: 1) 20 weeks with NI (20NI), 2) 24 weeks with NI (24NI), 3) 28 weeks with NI (28NI), 4) 14 weeks with NI + 10 weeks under natural SDs (24NISD), and 5) 14 weeks with NI + 14 weeks under natural SDs (28NISD). NI provided a TPFD of 4.5 µmol·m−2·s−1. Lengthening the production period and providing NI increased rhizome yield and crude fiber content in both species. SPAD index decreased when plants were exposed to natural SDs at the end of the production period (NISD treatments). Results demonstrate the potential to overcome winter dormancy of ginger and turmeric plants with NI, enabling higher rhizome yield under natural SDs.

Open Access

Nursery and greenhouse growers have an important role to play in conserving water resources. Many technologies are available to help growers conserve water. Yet, within the industry, there may be varying levels of knowledge about a specific strategy, along with inconsistent adoption and continued use. An understanding of these factors can be incorporated into educational programming for this audience. This study evaluated the reported knowledge level of U.S. greenhouse and nursery growers about eight specific water conservation technologies and then explored the rate at which growers had adopted and continued or discontinued their use. Technologies were ranked from high to low adoption rate, beginning with drip irrigation, rainwater capture, water reuse, and microirrigation, followed by soil moisture sensors, climate-based irrigation, subirrigation, and finally an irrigation audit. Overall, greater levels of knowledge corresponded to both greater adoption and continued use of a technology. Other factors, such as economic cost and technical feasibility are undoubtedly important. Findings highlight an opportunity to focus educational programs on the systems-based strategies that are beneficial to growers, but growers are least knowledgeable about to increase adoption of effective water conservation methods that currently have low levels of grower implementation.

Free access

The objective of this study was to compare strategies using water-soluble fertilizers (WSF) and controlled-release fertilizers (CRF) to provide adequate nutrition during both production and consumer phases of petunia (Petunia ×hybrida). Strategies included a CRF with a second prill coating (DCT) that delayed initial nutrient release, compared with a conventional single-coated CRF (OSM) and WSF. Rooted cuttings of petunia were grown for 42 days in trade 1-gal (2.84-L) containers (the “production phase”) with WSF only, a low rate of combined WSF and substrate-incorporated OSM, or low and high label rates of WSF and top-dressed (TD) OSM (WSF + OSM TD), WSF and substrate-incorporated DCT (WSF + DCT), OSM, or a commercial blend of substrate-incorporated OSM and DCT (OSM + DCT). By the end of production phase after 42 days, all fertilizer strategies tested produced horticulturally acceptable plants in terms of chlorophyll index and number of flowers. In a subsequent “consumer phase,” plants were maintained in containers or were transplanted into a landscape and irrigated with clear water for 98 days. Plant performance [number of flowers, SPAD chlorophyll index, dry weight, and tissue nitrogen (N) level] was greater during the consumer phase in treatments with high rates of CRF compared with WSF only or lower rates of CRF. On the basis of nutrient release in a sand substrate without plants at 10, 21, or 32 °C, the DCT had delayed nutrient release compared with single-coated CRF. The release rates of all CRF products and the duration of the delay in release from DCT were temperature dependent. A partial budget found that the lowest cost treatment was WSF only at $0.02/container. Comparing at high application rates, using WSF + DCT ($0.085/container) was more expensive than incorporated OSM ($0.05/container) and had a similar cost to WSF + OSM TD ($0.084/container). The greatly improved consumer performance for plants with residual fertilizer compared with WSF provides an opportunity to add value and profitability if a slightly higher sales price could be obtained. Several fertilizer strategies are available depending on material and labor cost and availability and preferred crop management style.

Full access

The objective was to evaluate and compare foliar spray and soil drench application methods of iron (Fe) for correcting Fe deficiency in hybrid calibrachoa (Calibrachoa × hybrida) grown in a container medium at pH 6.9 to 7.4. Untreated plants showed severe chlorosis and necrosis, stunting, and lack of flowering. An organosilicone surfactant applied at 1.25 mL·L-1 (0.160 fl oz/gal) increased uptake of Fe from foliar applications of both ferrous sulfate (FeSO4) and ferric ethylenediamine tetraacetic acid (Fe-EDTA). Foliar sprays at 60 mg·L-1 (ppm) Fe were more effective when Fe was applied as Fe-EDTA than FeSO4. Increasing Fe concentration of foliar sprays up to 240 mg·L-1 Fe from Fe-EDTA or 368 mg·L-1 Fe (the highest concentrations tested) from ferric diethylenetriamine pentaacetic acid (Fe-DTPA) increased chlorophyll content compared with lower spray concentrations, but leaf necrosis at the highest concentrations may have been caused by phytotoxicity. Drenches with ferric ethylenediaminedi(o-hydroxyphenylacetic) acid (Fe-EDDHA) at 20 to 80 mg·L-1 Fe were highly effective at correcting Fe-deficiency symptoms, and had superior effects on plant growth compared with drenches of Fe-DTPA at 80 mg·L-1 Fe or foliar sprays. Efficacy of Fe-DTPA drenches increased as concentration increased from 20 to 80 mg·L-1 Fe. An Fe-EDDHA drench at 20 to 80 mg·L-1 Fe was a cost-effective option for correcting severe Fe deficiency at high medium pH.

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The objective was to quantify the effect of the timing of macronutrient applications on nutrient uptake, growth, and development of Petunia ×hybrida Hort. Vilm.-Andr. ‘Supertunia Royal Velvet’ during vegetative propagation. Starting with unrooted cuttings (Day 0), fertigation was applied continuously at three time intervals (Day 0 to 7, Day 8 to 14, or Day 15 to 21) using either a “complete” (C) water-soluble fertilizer containing (in mg·L−1) 75 NO3-N, 25 NH4-N, 12 phosphorus (P), 83 potassium (K), 20 calcium (Ca), 10 magnesium (Mg), 1.4 sulfur (S), 2 iron (Fe), 1 manganese (Mn), 1 zinc (Zn), 0.5 copper (Cu), 0.5 boron (B), and 0.2 molybdenum (Mo) or a micronutrient fertilizer (M) containing (in mg·L−1) 1.4 S, 2 Fe, 1 Mn, 1 Zn, 0.5 Cu, 0.5 B, and 0.2 Mo in a complete factorial arrangement. With constant fertigation using the C fertilizer, plant dry weight (DW) doubled from Day 0 (sticking of unrooted cuttings) to Day 7 (0.020 g to 0.047 g), root emergence was observed by Day 4, and by Day 7, the average length of primary roots was 2.6 cm. During any week that the M fertilizer was substituted for the C fertilizer, tissue N–P–K concentrations decreased compared with plants receiving the C fertilizer. For example, plants receiving the M fertilizer between Day 0 and 7 had 20% lower tissue-N concentration at Day 7 compared with those receiving the C fertilizer. Although both shoot DW and leaf count increased once macronutrient fertilization was resumed after Day 7, final shoot DW and leaf count were lower than plants receiving C fertilizer from Day 0 to 21. Time to first root emergence was unaffected by fertigation. Constant application of C resulted in a higher shoot-to-root ratio at Day 21 than all other treatments. Results emphasize the importance of early fertigation on petunia, a fast-rooting species, to maintain tissue nutrient levels within recommended ranges.

Free access

There are many water treatment technologies available to the nursery and greenhouse industry, but this sector has been somewhat hesitant to adopt them. An online survey was used to evaluate nursery and greenhouse growers’ knowledge, implementation, and continued use of 12 water treatment technologies. Less than 24% of the growers had used a water treatment technology. The knowledge level was low overall, and fewer than one in four growers had implemented all 12 technologies. However, most growers who had implemented 10 of the 12 technologies continued to use them. The results imply water treatment technologies available for this group are somewhat unknown and underused, thereby implying that there is a need to increase awareness of these innovations and highlight the opportunity for growers to advocate for treatment technology use among their peers.

Open Access

The overall goal was to evaluate fertilizer options for greenhouse producers, with or without a plant growth regulator (PGR) application, to improve subsequent performance of container-grown annuals. Petunia (Petunia × hybrida) was the model container-grown crop in simulated production and consumer environments. The first experiment at two locations (New Hampshire and Florida) compared strategies using water-soluble fertilizer [WSF (17N–1.8P–14.1K)], controlled-release fertilizers (CRF), and slow-release fertilizers (SRF) that were either applied throughout or at the end of the 8-week production phase [point of shipping (POS)] for petunia rooted cuttings grown in 8-inch azalea containers. In the subsequent simulated “consumer” phase, container plants were irrigated with clear water (no fertilizer) for 6 weeks. Plant performance [number of flowers, SPAD chlorophyll index, dry weight, and tissue nitrogen (N)] at the end of the consumer phase was improved by top-dressing at POS with either CRF or granular organic fertilizer (both at 2.74 g/container N), or preplant incorporation of either a typical CRF at 4.12 g/container N or a CRF with an additional prill coating to delay initial release (DCT) at 2.74 g/container. There was no carry-over benefit from applying a liquid urea-chain product (1.37 or 2.74 g/container N) or top dressing with granular methylene di-urea (2.74 g/container N), or 400 mg·L–1 N (0.2 g/container N) from a liquid organic fertilizer at POS. The consumer benefit of applying 400 mg·L–1 N (0.2 g/container N) from a WSF at POS was increased by supplementing with 235 mg·L–1 magnesium (Mg) and 10 mg·L–1 iron (Fe). A second experiment in 10-inch-diameter pots evaluated the effect on consumer performance from providing 200 or 400 mg·L–1 N of WSF with the PGR paclobutrazol, at the final 1 L/pot irrigation at POS. Application of 3 mg·L–1 paclobutrazol delayed leaf yellowing and reduced plant height, width, and shoot dry weight during the consumer phase, resulting in a more compact growth habit and higher plant quality compared with plants that received no PGR, regardless of WSF treatment. Addition of supplemental 235 mg·L–1 Mg and 10 mg·L–1 Fe to the high rate of WSF and PGR did not improve consumer performance compared with other treatments that included a PGR. Overall, the first experiment demonstrated that the most effective fertilizer strategies require a CRF or SRF that will release nutrients throughout the consumer phase, and that impact of liquid fertilizer options is limited because of lower N supply per container. A single application at POS of a high rate of WSF with supplemental Mg and Fe may have short-term benefits, for example while plants are in a retail environment. Growers should consider combining a residual fertilizer with a PGR application for premium, value-added container annuals.

Open Access

The objective was to analyze the physical, chemical, and biological water quality in horticulture irrigation systems in 24 ornamental plant greenhouses and nurseries in the United States. At each greenhouse or nursery, water was collected from up to five points (“Sample Types”) which included 1) “Source” from municipal or private well supplies, 2) “Tank” from enclosed storage containers, 3) “Subirrigation” from water applied to crops in ebb-and-flood systems, 4) “Furthest Outlet” that were irrigation emitters most distant from the Source, and 5) “Catchment Basin” from open outdoor retention areas. On average, Source water had the highest physical and microbial quality of Sample Types including the highest ultraviolet (UV) light transmission at 86%, lowest total suspended solids (TSS) at 3.1 mg·L−1, and lowest density of aerobic bacteria with 1108 cfu/mL of water. Average quality of recycled water from Subirrigation or Catchment Basins did not meet recommended levels for horticultural irrigation water for UV transmission (68% to 72% compared with recommended 75%), microbial counts (>100,000 cfu/mL compared with recommended <10,000 cfu/mL), and chemical oxygen demand (COD) (48.2 to 61.3 mg·L−1 compared with recommended <30 mg·L−1). Irrigation water stored in Tanks or applied at Furthest Outlets had lower physical and biological water quality compared with Source water. Level of aerobic bacteria counts highlighted a risk of clogged microirrigation emitters from microbial contaminants, with highest bacteria levels in recirculated irrigation water. The physical, chemical, and microbial water quality results indicate a need for more effective water treatment to improve biological water quality, particularly with recirculated irrigation.

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Pine (Pinus sp.) wood products have potential to immobilize fertilizer nitrogen (N) and influence plant growth when used in soilless substrates for the production of containerized floriculture crops. Peat substrate was amended with (by volume) 30% pine wood fiber (peat:fiber) during a production phase with fertigation and a simulated consumer retail phase with clear-water irrigation using container-grown ‘Supertunia Vista Bubblegum’ petunia (Petunia ×hybrida). The objective was to evaluate substrate effects on substrate and plant tissue nutrient level and plant growth, with an emphasis on evaluating N immobilization from wood product amendments. Substrates consisting of peat amended with hammer-milled pine wood (peat:wood) or coconut (Cocos nucifera) coir (peat:coir) were used for comparison, and a 100% peat substrate (peat) served as a control. In Expt. 1, amending peat with pine wood fiber had no effect on leaf SPAD chlorophyll index, shoot growth, plant height and width, substrate N, or percent shoot tissue N at the end-of-production. In Expt. 2, plants grown in peat:fiber had reduced flower number, plant height and width, and shoot growth compared with plants grown in the 100% peat control. However, petunia grown in peat:fiber substrates maintained dark-green foliage with high leaf SPAD chlorophyll index values (≥44.4) and ≥45 flowers/plant, and therefore were considered marketable plants. During the production phase in both Expts. 1 and 2, N concentrations remained within the target range for petunia in both the shoot tissue and root-zone for all substrates. In addition, there was no statistical evidence of N immobilization for any substrate blend for either of the N drawdown procedures. In both Expts. 1 and 2, root-zone nutrients became depleted during the consumer phase when irrigation was with clear water (no fertilizer), and petunia developed uniform symptoms of leaf chlorosis and N deficiency. Results of this study indicate that peat amended with 30% pine wood fiber, hammer-milled pine wood, and coconut can be used for production of containerized petunia with minimal effects on plant growth or need to adjust the fertilizer program. However, increasing pine wood to >30% of the substrate volume may require growers to increase fertilization and adjust irrigation practices to compensate for greater risk of N immobilization and changes in substrate physical properties.

Open Access