@article{durand_jackson_fonteno_michel_2023, title={Particle size distribution of growing media constituents using dynamic image analysis: Parametrization and comparison to sieving}, ISSN={["1435-0661"]}, DOI={10.1002/saj2.20518}, abstractNote={Growing media constituents have heterogeneous particle size and shape, and their physical properties are partly related to them. Particle size distribution is usually analyzed through sieving process, segregating the particles by their width. However, sieving techniques are best describing more granular shapes and are not as reliable for materials exhibiting large varieties of shapes, like growing media constituents. A dynamic image analysis has been conducted for a multidimensional characterization of particle size distribution of several growing media constituents (white and black peats, pine bark, coir, wood fiber, and perlite), from particles that were segregated and dispersed in water. Diameters describing individual particle width and length were analyzed, then compared to particle size distribution obtained by dry and wet sieving methods. This work suggests the relevance of two parameters, FeretMAX and ChordMIN diameters for assessing particle length and width, respectively. They largely varied among the growing media constituents, confirming their non-spherical (i.e., elongated) shapes, demonstrating the advantages of using dynamic image analysis tools over traditional sieving methods. Furthermore, large differences in particle size distribution were also observed between dynamic image analysis and sieving procedures, with a finer distribution for dynamic image analysis. The discrepancies observed between methodologies were discussed (particle segregation, distribution weighing, etc.), while describing in details methodological limitations of dynamic image analysis.}, journal={SOIL SCIENCE SOCIETY OF AMERICA JOURNAL}, author={Durand, Stan and Jackson, Brian E. and Fonteno, William C. and Michel, Jean-Charles}, year={2023}, month={Apr} }
 @article{bartley iii_yap_jackson_fonteno_boyette_chaves-cordoba_2023, title={Quantifying the Sorptive Behavior of Traditional Horticultural Substrate Components Based on Initial Hydraulic Conditioning}, volume={58}, ISSN={["2327-9834"]}, DOI={10.21273/HORTSCI16698-22}, abstractNote={The ability of a substrate component (organic or inorganic) to capture and retain water (hydration and wettability) is important to investigate and promote water-use–efficient practices. Many factors may play a role in the wettability of the material, including the processing of the material and its initial handling. The goal of this experiment was to determine the effect of moisture content (MC) on the sorptive behavior of substrates after an initial and secondary hydration cycle. Coir, peat, and aged pine bark were evaluated at a 33%, 50%, and 66% MC by weight. At all moisture levels, coir and bark were minimally affected by MC or the initial hydration cycle. Peat was the most vulnerable to changes in sorptive behavior as a result of wetting and drying cycles. After a wetting and drying cycle, the maximum volumetric water content of peat from surface irrigation was reduced 21.5% (volumetrically), more than three times any other treatment. The hydration efficiency of peat was improved when blended with as little as 15% coir. These experiments provide evidence that MC and initial handling of the substrate can lead to differences in initial water use efficiency.}, number={1}, journal={HORTSCIENCE}, author={Bartley III, Paul C. and Yap, Ted C. and Jackson, Brian E. and Fonteno, William C. and Boyette, Michael D. and Chaves-Cordoba, Bernardo}, year={2023}, month={Jan}, pages={79–83} }
 @article{durand_jackson_fonteno_michel_2023, title={Quantitative Description and Classification of Growing Media Particle Morphology through Dynamic Image Analysis}, volume={13}, ISSN={["2077-0472"]}, DOI={10.3390/agriculture13020396}, abstractNote={The physical properties of growing media are dependent on the morphological characteristics of the particles composing them. Thus, their characteristics can be more precisely altered for specific purposes by a better morphological design of materials to optimize the use of raw materials and increase water efficiency. There are many references on the relationship between basic particle size and physical properties, but the arrangement of the particles and the resulting physical properties are also affected by the shape of the particles. Growing media have seldom been characterized by shape criteria and, therefore, their influence remains unknown. A dynamic image analyzer, the QicPic device, was used to assess particle shape and size for a wide diversity of growing media constituents. As well as FeretMAX and ChordMIN diameters describing individual particle length and width, respectively, individual particle shape was analyzed in terms of several descriptors (aspect ratio, circularity, roundness, and convexity). A classification was established to discern different particle shapes and all materials were described accordingly. Correlations between particle morphology descriptors were reported, showing that the greater the particle length, the smaller the width/length ratio, circularity, roundness, and convexity. Circularity, roundness, particle length, and its associated relative span were identified as the most relevant parameters describing materials’ morphology. This work shows a large diversity in particle morphology of growing media constituents, which were categorized into four classes of materials. Three classes were mainly described according to their particle shapes, with a decreasing elongation and an increasing circularity, roundness, and convexity: (1) fine and coarse wood and coir fibers; (2) all Sphagnum white peats, milled or sod; and (3) black peats, sedge peat, coir pith, fresh and composted pine bark, green waste compost, and perlite. A fourth class was represented by coir medium (mixing pith and fibers) and was above all characterized by high diversity in particle length. These findings extend the characterization of the materials for a more thorough evaluation of the links between particle morphology and physical properties.}, number={2}, journal={AGRICULTURE-BASEL}, author={Durand, Stan and Jackson, Brian E. and Fonteno, William C. and Michel, Jean-Charles}, year={2023}, month={Feb} }
 @article{woznicki_jackson_sonsteby_kusnierek_2023, title={Wood Fiber from Norway Spruce-A Stand-Alone Growing Medium for Hydroponic Strawberry Production}, volume={9}, ISSN={["2311-7524"]}, DOI={10.3390/horticulturae9070815}, abstractNote={There is an increased interest in the hydroponic production of strawberries in protected cultivation systems, and it is, therefore, urgent to develop new, more sustainable growing media alternatives. This study investigated the physical properties of wood fiber produced from Norway spruce (Picea abies (L.) H. Karst.) and peat:wood fiber substrate blends as well as the performance of the wood fiber in comparison to the industry standards, i.e., peat and coconut coir in the cultivation of hydroponic strawberry. Tray plants of the June-bearing strawberry (Fragaria × ananassa Duch.) cultivar ‘Malling Centenary’ were transplanted into five different growing media: a peat (80%) and perlite (20%) mixture, stand-alone (100%) coconut coir and three stand-alone (100%) Norway spruce wood fiber substrates (including coarse textured fibers with compact and loose packing density and compacted fine-textured fibers). Ripe strawberries were harvested and registered throughout the production season. The overall marketable yield was comparable across all the tested growing media; however, after 4 weeks of harvest, both coarse wood fiber and fine wood fiber showed better fruiting performance than the peat-perlite mixture. A trend for earlier berry maturation was observed for all wood fiber-based substrates. Plant parameters recorded after the end of production showed that plant height, number of leaves, and biomass production were higher in coarse wood fiber than in the peat-perlite mixture. Moreover, plants grown in wood fiber-based substrates had less unripe berries and flowers not harvested in comparison to both the peat and coir treatments.}, number={7}, journal={HORTICULTURAE}, author={Woznicki, Tomasz and Jackson, Brian E. and Sonsteby, Anita and Kusnierek, Krzysztof}, year={2023}, month={Jul} }
 @misc{bartley_fonteno_jackson_2022, title={A Review and Analysis of Horticultural Substrate Characterization by Sieve Analysis}, volume={57}, ISSN={["2327-9834"]}, DOI={10.21273/HORTSCI16583-22}, abstractNote={The physical, hydrological, and physico-chemical properties of horticultural substrates are influenced by particle shape and size. Sieve analysis has been the predominate method used to characterize the particle size distribution of horticultural substrates. However, the literature shows a diversity of techniques and procedures. The effects of agitation time and sample size on particle size distributions of soilless substrates were evaluated for several measures of sieve analysis, including sieve rate (a calculation of the percentage of material passed for each unit time of agitation), distribution median, sd , mass relative span, skewness, and kurtosis. To obtain the standard sieve rate (0.1%/min), pine bark, peat, perlite, and coir required agitation times of 4 minutes and 47 seconds, 7 minutes and 18 seconds, 10 minutes, and 11 minutes, respectively. However, there was concern that unwanted particle breakdown may occur during the particle size analysis of some materials. Therefore, a sieve rate (0.15%/min) for more friable materials was also determined. As a result, the endpoint of sieving was reached sooner for pine bark, peat, perlite, and coir, at 3 minutes and 10 seconds, 4 minutes and 42 seconds, 5 minutes and 14 seconds, and 6 minutes and 24 seconds, respectively. Increasing agitation time resulted in decreased distribution median, sd , and skewness for all materials. Sample sizes half and twice the volume of the recommended initial volume sieved did not change particle size distributions. For more precise characterization of particle size distributions when characterizing substrate components, agitation times and sample sizes should be specified for each material or collectively for all materials to ensure consistency and allow comparisons between results.}, number={6}, journal={HORTSCIENCE}, author={Bartley, Paul C., III and Fonteno, William C. and Jackson, Brian E.}, year={2022}, month={Jun}, pages={715–725} }
 @article{dickson_helms_jackson_machesney_lee_2022, title={Evaluation of Peat Blended with Pine Wood Components for Effects on Substrate Physical Properties, Nitrogen Immobilization, and Growth of Petunia (Petunia x hybrida Vilm.-Andr.)}, volume={57}, ISSN={["2327-9834"]}, DOI={10.21273/HORTSCI16177-21}, abstractNote={The first objective was to evaluate wood components for differences in nitrogen (N) immobilization and effects on substrate physical properties. The second objective was to evaluate peat substrates amended with pine wood components for effects on plant growth, shoot tissue N, and fertigation practices during production. Substrates consisted of a coarse sphagnum peat blended with four types of processed pine wood at rates of 15%, 30%, 45%, and 60% (by volume). For comparison, peat was also blended with an aged pine bark, perlite, and coconut coir. Nitrogen immobilization was measured for individual components, except perlite. Individual components and blended substrates were evaluated for particle size distribution, total air porosity, container capacity, and dry bulk density. In a greenhouse experiment, petunia ( Petunia × hybrida Vilm.-Andr.) were grown in hanging basket containers with each substrate blend as well as 100% peat, which served as a nonblended control substrate, and fertilized at each irrigation with 200 mg·L −1 N. Blended component and blend percent interacted in effects on all measured substrate physical properties; however, physical properties of all substrate blends were considered adequate for horticultural purposes. In the laboratory, pine bark immobilized 9% of total N supplied, whereas the remaining pine wood components immobilized <5% of total N. In the greenhouse experiment, blend component influenced shoot growth and flowering, which were greatest for petunia grown in 100% peat. Increasing the blend percent of all components decreased shoot growth and flowering with all blended components. Blended substrates had minimal effects on number of fertigation events, and substrate treatments differed by a maximum of three fertigation events per container over a 56-d period. This study illustrates the challenges of measuring N immobilization because results from the laboratory were not consistent with plant performance in the greenhouse. Increasing blends of each substrate (including perlite) were also observed to interact with fertigation practices and therefore applied N, tissue N, shoot dry weight, and total N uptake. As a practical conclusion from this study, peat incorporated with 60% wood fiber increased the risk of reduced plant growth and N uptake, but this risk was lower as the blend percentage decreased. In addition, other analytical methods to test N immobilization, such as microbial respiration, should be further explored.}, number={2}, journal={HORTSCIENCE}, author={Dickson, Ryan W. and Helms, Kalyn M. and Jackson, Brian E. and Machesney, Leala M. and Lee, Jung Ae}, year={2022}, month={Feb}, pages={304–311} }
 @article{bartley_amoozegar_fonteno_jackson_2022, title={Particle Densities of Horticultural Substrates}, volume={57}, ISSN={["2327-9834"]}, DOI={10.21273/HORTSCI16319-21}, abstractNote={The heterogeneity of horticultural substrates makes basic physical characteristics, such as total porosity and particle density, difficult to estimate. Due to the material source, inclusion of occluded pores, and hydrophobicity, particle density values reported from using liquid pyknometry, vary widely. Gas pycnometry was used to determine the particle density of coir, peat, perlite, pine bark, and wood substrates. Further precision was examined by gas species and separation by particle size. The calculated particle densities for each material determined by He, N 2 , and air were relatively constant and varied little despite the species of gas used. Particle size affected the measured particle density of perlite and pine bark but was minimal with coir, peat, and wood. Reducing the particle size removed more occluded pores and the measured particle density increased. Given the small variability, the use of particle density values obtained by gas pycnometry provides repeatable, precise measurements of substrate material total porosity.}, number={3}, journal={HORTSCIENCE}, author={Bartley, Paul C., III and Amoozegar, Aziz and Fonteno, William C. and Jackson, Brian E.}, year={2022}, month={Mar}, pages={379–383} }
 @article{nguyen_kraska_winkler_aydinlik_jackson_pude_2022, title={Primary Mechanical Modification to Improve Performance of Miscanthus as Stand-Alone Growing Substrates}, volume={12}, ISSN={["2073-4395"]}, DOI={10.3390/agronomy12020420}, abstractNote={Selecting proper mechanical processing can improve performance of miscanthus substrates. We studied the effects of mechanical processing methods on substrate morphology, hydrological properties, pH, and nitrogen immobilization. Miscanthus × giganteus biomass was processed into field chips (FC, forage harvester), shreds (S5, mechanical fraying machine through a 5-mm screen) and chips (C15, C10, C5 and C3, hammermill with screen size of 15, 10, 5, or 3 mm). Processed miscanthus materials were also tested as propagation substrates for Chinese cabbage seedlings. Results showed that particle size distribution of miscanthus substrates formed four groups in ascending order of particle size: C3 < C5 < (C10, C15, S5) < FC. The finer miscanthus substrates had higher water holding capacity following the same groupings in particle size. The hydrophobicity of processed miscanthus was low and reversible, with the increasing order of risk as C3 < C5 < C10, C15 < S5, FC. All miscanthus substrates had similar and low pH buffering capacity. Nitrogen immobilization was similar among miscanthus substrates. The seedlings in miscanthus substrates had similar germination rates but a lower biomass compared to those grown in peat and coir. Primary mechanical modification of miscanthus offers opportunities for different sizes of substrate materials with few changes to the physical or chemical properties tested in this work.}, number={2}, journal={AGRONOMY-BASEL}, author={Nguyen, Van T. H. and Kraska, Thorsten and Winkler, Winona and Aydinlik, Sercan and Jackson, Brian E. and Pude, Ralf}, year={2022}, month={Feb} }
 @article{poleatewich_michaud_jackson_krause_degenring_2022, title={The Effect of Peat Moss Amended with Three Engineered Wood Substrate Components on Suppression of Damping-Off Caused by Rhizoctonia solani}, volume={12}, ISSN={["2077-0472"]}, DOI={10.3390/agriculture12122092}, abstractNote={The use of wood-derived materials in soilless substrates for horticultural crop production is increasing; however, there is little information about the effects of wood on the incidence and severity of soilborne diseases of container-grown plants. The objectives of this research were to compare three differently processed wood substrate components blended with sphagnum peat and to investigate the effect of the peat:wood blend ratio on damping-off disease caused by Rhizoctonia solani using radish as a model system. In objective one, raw sphagnum peat was blended with three types of processed pine wood, screw-extruded, twin disc-refined, and hammer-milled, at a volumetric ratio of 70:30 and compared to a 70:30 peat:perlite mix. Radish plants grown in the hammer-milled wood and disc-refined wood had significantly lower damping-off disease severity compared to plants grown in the peat–perlite control. In objective two, sphagnum peat was blended with the three types of processed wood at a volumetric ratio of 90:10, 80:20, and 70:30 and compared to a 70:30 peat–perlite mix. The effect of the blend ratio varied by wood processing type. Higher percentages of Forest Gold and pine tree substrate resulted in lower disease severity. In both objectives, radish plants grown in any of the substrate treatments containing wood infested with R. solani tended to have lower disease severity compared to plants in the control. Results of this study indicate that the blending of processed pine wood-derived components into peat may enhance the natural suppression of damping-off disease of radish. Further research is needed to elucidate the mode of action of wood-derived materials on disease suppression in container-grown crops and to study the effects for other plant pathogens and crop species.}, number={12}, journal={AGRICULTURE-BASEL}, author={Poleatewich, Anissa and Michaud, Isobel and Jackson, Brian and Krause, Matthew and DeGenring, Liza}, year={2022}, month={Dec} }
 @article{li_hu_li_truong_li_lin_naik_xiang_jackson_kuo_et al._2021, title={Enhancing the multi-functional properties of renewable lignin carbon fibers via defining the structure-property relationship using different biomass feedstocks}, volume={23}, ISSN={["1463-9270"]}, DOI={10.1039/d0gc03828h}, abstractNote={Lignin from different biomass feedstock has been explored to make quality carbon fiber. The mechanistic study revealed the <italic>β-O</italic>-4 linkages of lignin linearly correlated to both mechanical and electroconductive performance of carbon fibers.}, number={10}, journal={GREEN CHEMISTRY}, author={Li, Qiang and Hu, Cheng and Li, Mengjie and Truong, Phuc and Li, Jinghao and Lin, Hao-Sheng and Naik, Mandar T. and Xiang, Sisi and Jackson, Brian E. and Kuo, Winson and et al.}, year={2021}, month={May}, pages={3725–3739} }
 @article{schulker_jackson_fonteno_heitman_albano_2021, title={Exploring Substrate Water Capture in Common Greenhouse Substrates through Preconditioning and Irrigation Pulsing Techniques}, volume={11}, ISSN={["2073-4395"]}, DOI={10.3390/agronomy11071355}, abstractNote={Particles in a substrate create a network of pore pathways for water to move through, with size and shape determining the efficacy of these channels. Reduced particle size diversity can lead to increased leachate, poor substrate hydration, and an inefficient irrigation practice. This research examined the hydration characteristics of three greenhouse substrate components at three preconditioned initial moisture contents using subirrigation under five different irrigation durations and three water depths (2 mm, 20 mm, and 35 mm). Sphagnum peatmoss, coconut coir, and aged pine bark were tested at 67%, 50%, and 33% initial moisture (by weight). The objectives were to determine the impact of varying irrigation event durations (5, 10, 20, 30, 60 min) over a 60-min period, and the further influence of water depth and initial moisture, on the water capture abilities of peat, coir, and pine bark. The number of irrigation events depended on the irrigation event time of that experimental unit divided by the total time of 60 min, varying from 12, 6, 3, 2, and 1 event. Hydration efficiency was influenced by initial moisture content (IMC), water depth, pulsing duration, and inherent substrate characteristics (hydrophobicity/hydrophilicity). Initial MC had the largest impact on peat, regardless of water level or irrigation duration. Lower IMCs increased the hydrophobic response of peat, further reducing the amount of water the substrate was able to absorb. Pine bark had a 5–10% decrease in initial hydration between 67%, 50%, and 33% IMC, while coir’s hydrophilic nature reduced any IMC affects. At 50% IMC or less, coir had the highest volumetric water content (VWC) across all substrates, pulsing durations, and water depths. Water depth was found to increase initial hydration and final hydration 6–8% across all substrates. These three materials had altered and varied water capture responses depending on the combination of treatments employed. This work demonstrated the effects of intensity and exposure on substrates and the need for more integrated research for improving water use efficiency on container crops.}, number={7}, journal={AGRONOMY-BASEL}, author={Schulker, Brian A. and Jackson, Brian E. and Fonteno, William C. and Heitman, Joshua L. and Albano, Joseph P.}, year={2021}, month={Jul} }
 @article{smith_jackson_whipker_fonteno_2021, title={Industrial hemp vegetative growth affected by substrate composition}, volume={1305}, ISSN={["2406-6168"]}, DOI={10.17660/ActaHortic.2021.1305.12}, journal={III INTERNATIONAL SYMPOSIUM ON GROWING MEDIA, COMPOSTING AND SUBSTRATE ANALYSIS}, author={Smith, J. T. and Jackson, B. E. and Whipker, B. E. and Fonteno, W. C.}, year={2021}, pages={83–89} }
 @article{suchoff_jackson_gunter_schultheis_louws_2021, title={Non-destructive characterization of grafted tomato root systems using the mini-horhizotron}, volume={1302}, ISSN={["2406-6168"]}, url={https://publons.com/wos-op/publon/56007334/}, DOI={10.17660/ActaHortic.2021.1302.28}, journal={II INTERNATIONAL SYMPOSIUM ON VEGETABLE GRAFTING}, author={Suchoff, D. H. and Jackson, B. E. and Gunter, C. C. and Schultheis, J. R. and Louws, F. J.}, year={2021}, pages={209–214} }
 @article{durand_jackson_fonteno_michel_2021, title={The Use of Wood Fiber for Reducing Risks of Hydrophobicity in Peat-Based Substrates}, volume={11}, ISSN={["2073-4395"]}, DOI={10.3390/agronomy11050907}, abstractNote={Peat substrates are well known to become hydrophobic during desiccation, thus degrading their water retention properties. Synthetic wetting agents are commonly incorporated to limit the risk of hydrophobicity, but substrates companies are searching for more sustainable alternatives. To that end, the effect of wood fiber addition in peat-based mixes was measured using contact angles and hydration curves. The study was carried out on two raw materials (white milled peat and wood fiber) and binary mixes. The results showed a shift from hydrophilic to more hydrophobic character with a decrease in the ability to rewet of peat-based substrates in relation to the intensity of drying, whereas wood fiber remained hydrophilic. Increasing wood fiber content in peat-based mixes improved the rehydration efficiency, but with a lower intensity of that measured with synthetic wetting agent addition. Our results highlighted the hydrophilic nature of wood fiber and demonstrated an additional benefit of wood fiber use in peat-based growing media.}, number={5}, journal={AGRONOMY-BASEL}, author={Durand, Stan and Jackson, Brian E. and Fonteno, William C. and Michel, Jean-Charles}, year={2021}, month={May} }
 @article{michel_jackson_fonteno_2021, title={The use of coir for reducing risks of peat-based substrate hydrophobicity}, volume={1305}, ISSN={["2406-6168"]}, DOI={10.17660/ActaHortic.2021.1305.59}, journal={III INTERNATIONAL SYMPOSIUM ON GROWING MEDIA, COMPOSTING AND SUBSTRATE ANALYSIS}, author={Michel, J. C. and Jackson, B. E. and Fonteno, W. C.}, year={2021}, pages={449–454} }
 @article{schulker_jackson_fonteno_heitman_albano_2020, title={Comparison of Water Capture Efficiency through Two Irrigation Techniques of Three Common Greenhouse Soilless Substrate Components}, volume={10}, ISSN={["2073-4395"]}, DOI={10.3390/agronomy10091389}, abstractNote={Substrate wettability is an important factor in determining effective and efficient irrigation techniques for container-grown crops. Reduced substrate wettability can lead to lower substrate water capture, excessive leaching and poor plant growth. This research examined substrate water capture using surface and subirrigation under three initial moisture contents (IMC). Sphagnum peat moss, coconut coir, and pine bark were tested at IMCs of 67% 50%, and 33%. Substrate water capture was influenced by both IMC and irrigation technique. Surface irrigation increased the water capture of coir and peat, regardless of IMC, whereas IMC influenced pine bark water capture more than irrigation method. Surface-irrigated coir at or above 50% IMC provided the greatest water capture across all treatments. The first irrigation had the highest capture rate compared to all other events combined. Container capacities of pine bark and coir were unaffected by IMC and irrigation type, but the CC of peat was less by ~ 40% volumetrically under low IMC conditions. Coir, had the greatest ability to capture water, followed by pine bark and peat, respectively. Moisture content, irrigation type and component selection all influence the water capture efficiency of a container substrate.}, number={9}, journal={AGRONOMY-BASEL}, author={Schulker, Brian A. and Jackson, Brian E. and Fonteno, William C. and Heitman, Joshua L. and Albano, Joseph P.}, year={2020}, month={Sep} }
 @article{shreckhise_owen_eick_niemiera_altland_jackson_2020, title={Dolomite and Micronutrient Fertilizer Affect Phosphorus Fate When Growing Crape Myrtle in Pine Bark}, volume={55}, ISSN={["2327-9834"]}, DOI={10.21273/HORTSCI14558-20}, abstractNote={Soilless substrates are routinely amended with dolomite and sulfate-based micronutrients to improve fertility, but the effect of these amendments on phosphorous (P) in substrate pore-water during containerized crop production is poorly understood. The objectives of this research were as follows: compare the effects of dolomite and sulfate-based micronutrient amendments on total P (TP), total dissolved P (TDP), orthophosphate P (OP), and particulate P (PP; TP − TDP) concentrations in pour-through extracts; to model saturated solid phases in substrate pore-water using Visual MINTEQ; and to assess the effects of dolomite and micronutrient amendments on growth and subsequent P uptake efficiency (PUE) of Lagerstroemia L. ‘Natchez’ (crape myrtle) potted in pine bark. Containerized crape myrtle were grown in a greenhouse for 93 days in a 100% pine bark substrate containing a polymer-coated 19N–2.6P–10.8K controlled-release fertilizer (CRF) and one of four substrate amendment treatments: no dolomite or micronutrients (control), 2.97 kg·m −3 dolomite (FL); 0.89 kg·m −3 micronutrients (FM); or both dolomite and micronutrients (FLM). Pour-through extracts were collected approximately weekly and fractioned to measure pore-water TP, TDP, and OP and to calculate PP. Particulate P concentrations in pour-through extracts were generally unaffected by amendments. Relative to the control, amending pine bark with FLM reduced water-extractable OP, TDP, and TP concentrations by ≈56%, had no effect on P uptake efficiency, and resulted in 34% higher total dry weight (TDW) of crape myrtle. The FM substrate had effects similar to those of FLM on plant TDW and PUE, and FM reduced pore-water OP, TDP, and TP concentrations by 32% to 36% compared with the control. Crape myrtle grown in FL had 28% lower TDW but pour-through OP, TDP, and TP concentrations were similar to those of the control. Chemical conditions in FLM were favorable for precipitation of manganese hydrogen phosphate (MnHPO 4 ), which may have contributed to lower water-extractable P concentrations in this treatment. This research suggests that amending pine bark substrate with dolomite and a sulfate-based micronutrient fertilizer should be considered a best management practice for nursery crop production.}, number={6}, journal={HORTSCIENCE}, author={Shreckhise, Jacob H. and Owen, James S., Jr. and Eick, Matthew J. and Niemiera, Alexander X. and Altland, James E. and Jackson, Brian E.}, year={2020}, month={Jun}, pages={832–840} }
 @article{harris_dickson_fisher_jackson_poleatewich_2020, title={Evaluating Peat Substrates Amended with Pine Wood Fiber for Nitrogen Immobilization and Effects on Plant Performance with Container-grown Petunia}, volume={30}, ISSN={["1943-7714"]}, DOI={10.21273/HORTTECH04526-19}, abstractNote={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.}, number={1}, journal={HORTTECHNOLOGY}, author={Harris, Crysta N. and Dickson, Ryan W. and Fisher, Paul R. and Jackson, Brian E. and Poleatewich, Anissa M.}, year={2020}, month={Feb}, pages={107–116} }
 @article{hembree_ranney_lynch_jackson_2020, title={Identification, Genome Sizes, and Ploidy of Deutzia}, volume={145}, ISSN={["2327-9788"]}, DOI={10.21273/JASHS04779-19}, abstractNote={The genus Deutzia, in the Hydrangeaceae family, includes ≈60 species that range in ploidy from diploid (2 x ) to tetradecaploid (14 x ). There have been extensive breeding efforts for Deutzia, but this has been limited to a few parental species. Although there have been numerous studies of the cytogenetics of some species of Deutzia , the ploidy level of many species remains unknown, and there are few cytogenetic data available for Deutzia hybrids and cultivars. The purpose of this study was to validate the identification and determine the genome sizes and ploidy of a diverse collection of Deutzia species and hybrids using cytology and flow cytometry. Accessions were identified using the most current taxonomic key and voucher specimens were deposited for each at the North Carolina State University herbarium. Corrected and updated species names are provided for all cultivars and accessions studied. Traditional cytology was performed for roots of representative taxa to calibrate the genome size with the ploidy level. The genome size and estimated ploidy were determined for 43 accessions using flow cytometry. Ploidy levels were reported for the first time for three species of Deutzia including D. calycosa (2 n = 4 x = 52), D. paniculata (2 n = 4 x = 52), and D. glauca (2 n = 12 x = 156). The base and monoploid genome size (1C x ) were somewhat variable and ranged from 1.20 to 2.05 pg. No anisoploid hybrids were documented, suggesting the presence of an interploid block. The information produced from this study are beneficial to future curation, research, development, and improvement of this genus with corrected nomenclature and clone-specific data regarding cytogenetics.}, number={2}, journal={JOURNAL OF THE AMERICAN SOCIETY FOR HORTICULTURAL SCIENCE}, author={Hembree, William G. and Ranney, Thomas G. and Lynch, Nathan P. and Jackson, Brian E.}, year={2020}, month={Mar}, pages={88–94} }
 @article{owen_jackson_fonteno_whipker_2020, title={Liming Requirements of Greenhouse Peat-based Substrates Amended with Pine Wood Chips as a Perlite Alternative}, volume={30}, ISSN={["1943-7714"]}, DOI={10.21273/HORTTECH04506-19}, abstractNote={Processed loblolly pine ( Pinus taeda ) wood has been investigated as a component in greenhouse and nursery substrates for many years. Specifically, pine wood chips (PWCs) have been uniquely engineered/processed into a nonfibrous blockular particle size suitable for use as a substrate aggregate. The objective of this research was to compare the dolomitic limestone requirements of plants grown in peat-based substrates amended with perlite or PWC. In a growth trial with ‘Mildred Yellow’ chrysanthemum ( Chrysanthemum × morifolium ), peat-based substrates were amended to contain 0%, 10%, 20%, 30%, 40%, or 50% (by volume) perlite or PWC for a total of 11 substrates. Substrates were amended with dolomitic limestone at rates of 0, 3, 6, 9, or 12 lb/yard 3 , for a total of 55 substrate treatments. Results indicate that pH of substrates amended with ≥30% perlite or PWC need to be adjusted to similar rates of 9 to 12 lb/yard 3 dolomitic limestone to produce similar-quality chrysanthemum plants. In a repeated study, ‘Moonsong Deep Orange’ african marigold ( Tagetes erecta ) plants were grown in the same substrates previously formulated (with the exclusion of the 50% ratio) and amended with dolomitic limestone at rates of 0, 3, 6, 9, 12, or 15 lb/yard 3 , for a total of 54 substrate treatments. Results indicate a similar dolomitic limestone rate of 15 lb/yard 3 is required to adjust substrate pH of 100% peatmoss and peat-based substrates amended with 10% to 40% perlite or PWC aggregates to the recommended pH range for african marigold and to produce visually similar plants. The specific particle shape and surface characteristics of the engineered PWC may not be similar to other wood products (fiber) currently commercialized in the greenhouse industry, therefore the lime requirements and resulting substrate pH may not be similar for those materials.}, number={2}, journal={HORTTECHNOLOGY}, author={Owen, W. Garrett and Jackson, Brian E. and Fonteno, William C. and Whipker, Brian E.}, year={2020}, month={Apr}, pages={219–230} }
 @article{bertucci_bartley_jennings_monks_jackson_2020, title={Quantification of palmer amaranth seed number using a computerized particle analyzer}, volume={5}, ISSN={["2471-9625"]}, DOI={10.1002/ael2.20003}, number={1}, journal={AGRICULTURAL & ENVIRONMENTAL LETTERS}, author={Bertucci, Matthew B. and Bartley, Paul C., III and Jennings, Katherine M. and Monks, David W. and Jackson, Brian E.}, year={2020} }
 @article{fields_fonteno_jackson_heitman_owen_2020, title={The Use of Dewpoint Hygrometry to Measure Low Water Potentials in Soilless Substrate Components and Composites}, volume={10}, ISSN={["2073-4395"]}, DOI={10.3390/agronomy10091393}, abstractNote={Plant water availability in soilless substrates is an important management consideration to maximize water efficiency for containerized crops. Changes in the characteristics (i.e., shrink) of these substrates at low water potential (<−1.0 MPa) when using a conventional pressure plate-base can reduce hydraulic connectivity between the plate and the substrate sample resulting in inaccurate measures of water retention. Soilless substrate components Sphagnum peatmoss, coconut coir, aged pine bark, shredded pine wood, pine wood chips, and two substrate composites were tested to determine the range of volumetric water content (VWC) of surface-bound water at water potentials between −1.0 to −2.0 MPa. Substrate water potentials were measured utilizing dewpoint hygrometry. The VWC for all components or composites was between 5% and 14%. These results were considerably lower compared to previous research (25% to 35% VWC) utilizing conventional pressure plate extraction techniques. This suggests that pressure plate measurements may overestimate this surface-bound water which is generally considered unavailable for plant uptake. This would result in underestimating available water by as much as 50%.}, number={9}, journal={AGRONOMY-BASEL}, author={Fields, Jeb S. and Fonteno, William C. and Jackson, Brian E. and Heitman, Joshua L. and Owen, James S., Jr.}, year={2020}, month={Sep} }
 @article{hembree_ranney_jackson_weathington_2019, title={Cytogenetics, Ploidy, and Genome Sizes of Camellia and Related Genera}, volume={54}, ISSN={["2327-9834"]}, DOI={10.21273/HORTSCI13923-19}, abstractNote={Camellia L., the most speciose member of the diverse tea family Theaceae, has a long and complex horticultural history. Extensive cultivation and hybridization have produced thousands of varieties of Camellia , including commercially important crops such as cultivated tea, oilseed, and iconic flowering shrubs. Cytogenetics of Camellia and related genera is complicated; chromosome number and ploidy can vary widely between species, and interspecific and interploid hybridization occurs. However, specific information regarding cytogenetics of many species, cultivars, and modern hybrids is lacking. The objectives of this study were to compile a consolidated literature review of the cytogenetics of Camellia and related genera and to determine chromosome numbers, ploidy, and genome sizes of specific accessions of selected species, cultivars, and interspecific and interploid hybrids. A review of the existing literature regarding Theaceae cytogenetics is presented as a consolidated reference comprising 362 taxa. Genome sizes were determined with flow cytometry using propidium iodide as a fluorochrome and Pisum sativum ‘Ctirad' and Magnolia virginiana ‘Jim Wilson’ as internal standards. Chromosome numbers of selected taxa were determined using traditional cytology and were used to calibrate genome sizes with ploidy level. Our results confirmed a base chromosome number of x = 15 for Theeae including Camellia , x = 17 for Stewartiae, and x = 18 for Gordoniae. Surveyed camellias ranged from 2 n = 2 x = 30 to 2 n = 8 x = 120, including diploids, triploids, tetraploids, pentaploids, hexaploids, and octoploids. Previously uncharacterized taxa such as Camellia azalea , C. amplexicaulis , C. chrysanthoides , C. cordifolia , C. cucphuongensis , C. flava , C. nanyongensis , and C. trichoclada were found to be diploid. Ploidy was also newly determined for Schima argentea , S. khasiana , S. remotiserrata , and S. sinensis (all diploids). Both diploid and triploid Stewartia ovata were found, and a ploidy series was discovered for Polyspora that ranged from diploid to octoploid. Ploidy determinations were used to confirm or challenge the validity of putative interploid hybrids. Monoploid genome sizes varied among subfamily and genera, with 1C x values ranging from 0.80 pg for Franklinia to a mean of 3.13 pg for Camellia , demonstrating differential rates of genome expansion independent of ploidy . Within Camellia, monoploid genome sizes varied among subgenera, sections, and some species (range, 2.70–3.55 pg). This study provides a consolidated and expanded knowledgebase of ploidy, genome sizes, hybridity, and reproductive pathways for specific accessions of Camellia and related genera that will enhance opportunities and strategies for future breeding and improvement within Theaceae.}, number={7}, journal={HORTSCIENCE}, author={Hembree, William G. and Ranney, Thomas G. and Jackson, Brian E. and Weathington, Mark}, year={2019}, month={Jul}, pages={1124–1142} }
 @article{bartley_jackson_fonteno_2019, title={Effect of particle length to width ratio on sieving accuracy and precision}, volume={355}, ISSN={["1873-328X"]}, DOI={10.1016/j.powtec.2019.07.016}, abstractNote={The physical, hydrological, and physico-chemical properties of horticultural substrates are influenced by particle shape and size. Sieve analysis is the predominate method utilized to characterize the particle size distribution of horticultural substrates. However, the effect of particle length on sieve analysis results have only been speculated. Laser cut particles with eight different length to width (L:W) ratios were sorted by sieves for agitation times ranging from 1 min to 5 min. To quantify the effect of L:W ratio and agitation time, the means (mid-point) and standard deviations of particle distributions were compared. Particles with a 1:1 L:W ratio were the most accurately sorted particles, containing midpoints most similar to true sieve size. As particle length increased, distribution midpoints and standard deviation increased. Elongated particles, 2:1 L:W ratio and greater, may cause the particle size distribution to skew positively. Increasing agitation time influences the probability of a particle and open sieve aperture converging in an orientation which allows it passage and can improve sieve accuracy and precision. By improving the consistency of sieving protocols, the accuracy of sieve analysis could potentially be improved. However, alternative instruments should be evaluated to improve the characterization of horticultural substrates. If, in the future, the characteristics of elongated or complex-shaped particles are desired, it may prove more beneficial to refine engineering practices than rely on sieving to precisely sort and isolate them.}, journal={POWDER TECHNOLOGY}, author={Bartley, Paul C., III and Jackson, Brian E. and Fonteno, William C.}, year={2019}, month={Oct}, pages={349–354} }
 @article{miller_pinnix_bartley_mccauley_jackson_2019, title={Evaluation of Turfgrass Clippings from Mulching Versus Side Discharge Mower Operation}, volume={5}, ISSN={["2374-3832"]}, DOI={10.2134/cftm2019.06.0050}, number={1}, journal={CROP FORAGE & TURFGRASS MANAGEMENT}, author={Miller, Grady L. and Pinnix, Garland D. and Bartley, Paul C. and McCauley, Raymond K. and Jackson, Brian E.}, year={2019}, month={Oct} }
 @article{stewart_marble_jackson_pearson_wilson_lauer_2019, title={Influence of Pine Bark Substrate Age on Performance and Leaching of Nursery Preemergence Herbicides}, volume={54}, ISSN={["2327-9834"]}, DOI={10.21273/HORTSCI13748-18}, abstractNote={The objective of these experiments was to determine if preemergence herbicides perform similarly across pine bark that was aged for varying lengths of time including 0, 4, 8, and 12 months after bark removal from harvested trees. Three preemergence herbicides were evaluated for three separate weed species, including 1) Cardamine flexuosa With. (bittercress) with isoxaben, 2) Digitaria sanguinalis (L.) Scop. (large crabgrass) with prodiamine, and 3) Oxalis stricta L. (woodsorrel) with dimethenamid-P. Leaching of herbicides through substrates was evaluated for prodiamine. Weed growth in the various substrates was variable, but few differences were detected in weed growth among the pine bark substrates evaluated. For isoxaben and prodiamine, weed control was similar among the pine bark substrates in most cases when label rates were applied. Although some differences were detected in prodiamine performance across different pine bark ages, a high level of control was achieved in all cases at rates well below manufacturer recommendations. Prodiamine leaching was minimal in all substrates. It would be recommended that growers test substrates for physical properties before use so that irrigation and other production inputs could be modified if needed. In most cases, growers should expect similar performance of preemergence herbicides regardless of pine bark substrate age.}, number={5}, journal={HORTSCIENCE}, author={Stewart, Cody J. and Marble, S. Christopher and Jackson, Brian and Pearson, Brian J. and Wilson, P. Christopher and Lauer, Dwight K.}, year={2019}, month={May}, pages={896–902} }
 @article{altland_owen_jackson_fields_2018, title={Physical and Hydraulic Properties of Commercial Pine-bark Substrate Products Used in Production of Containerized Crops}, volume={53}, ISSN={["2327-9834"]}, DOI={10.21273/HORTSCI13497-18}, abstractNote={Pine bark is the primary constituent of nursery container media (i.e., soilless substrate) in the eastern United States. Pine bark physical and hydraulic properties vary depending on the supplier due to source (e.g., lumber mill type) or methods of additional processing or aging. Pine bark can be processed via hammer milling or grinding before or after being aged from ≤1 month (fresh) to ≥6 month (aged). Additionally, bark is commonly amended with sand to alter physical properties and increase bulk density (D b ). Information is limited on physical or hydraulic differences of bark between varying sources or the effect of sand amendments. Pine bark physical and hydraulic properties from six commercial sources were compared as a function of age and amendment with sand. Aging bark, alone, had little effect on total porosity (TP), which remained at ≈80.5% (by volume). However, aging pine bark from ≤1 to ≥6 months shifted particle size from the coarse (>2 mm) to fine fraction (<0.5 mm), which increased container capacity (CC) 21.4% and decreased air space (AS) by 17.2% (by volume) regardless of source. The addition of sand to the substrate had a similar effect on particle size distribution to that of aging, increasing CC and D b while decreasing AS. Total porosity decreased with the addition of sand. The magnitude of change in TP, AS, CC, and D b from a nonamended pine bark substrate was greater with fine vs. coarse sand and varied by bark source. When comparing hydrological properties across three pine bark sources, readily available water content was unaffected; however, moisture characteristic curves (MCC) differed due to particle size distribution affecting the residual water content and subsequent shift from gravitational to either capillary or hygroscopic water. Similarly, hydraulic conductivity (i.e., ability to transfer water within the container) decreased with increasing particle size.}, number={12}, journal={HORTSCIENCE}, author={Altland, James E. and Owen, James S., Jr. and Jackson, Brian E. and Fields, Jeb S.}, year={2018}, month={Dec}, pages={1883–1890} }
 @article{evans_jackson_popp_sadaka_2017, title={Chemical Properties of Biochar Materials Manufactured from Agricultural Products Common to the Southeast United States}, volume={27}, ISSN={["1943-7714"]}, DOI={10.21273/horttech03481-16}, abstractNote={The use of biochar as a soil amendment has fostered much attention in recent years due to its potential of improving the chemical, physical, and biological properties of agricultural soils and/or soilless substrates. The objective of this study was to evaluate the chemical properties of feedstocks, common in the southeast United States, and their resulting biochar products (after being torrefied) and determine if the chemical properties were within suitable ranges for growers to use the biochar products as root substrate components. Poultry litter biochar produced at 400 °C for 2 hours had a higher total phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), chloride (Cl), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), sodium (Na), and zinc (Zn) concentration than biochar made using the same process with mixed hard wood species, miscanthus ( Miscanthus capensis ), cotton ( Gossypium hirsutum ) gin trash, switchgrass ( Panicum virgatum ), rice ( Oryza sativa ) hull, and pine ( Pinus sp.) shavings feedstocks. The pH of the biochar products ranged from 4.6 for pine shaving biochar to 9.3 for miscanthus biochar. The electrical conductivity (EC) ranged from 0.1 dS·m −1 for mixed hardwood biochar to 30.3 dS·m −1 for poultry litter biochar. The cation exchange capacity (CEC) of the biochar products ranged from a low of 0.09 meq/g for mixed hardwood biochar to a high of 19.0 meq/g for poultry litter biochar. The water-extractable nitrate, P, K, Ca, Mg, sulfate, boron, Cl, Cu, Fe, Mo, Na, and Zn were higher in poultry litter biochar than in all of the other types of biochar. The high EC and mineral element concentration of the poultry litter biochar would prevent its use in root substrates except in very small amounts. In addition, the high degree of variability in chemical properties among all of the biochar products would require users to know the specific properties of any biochar product they used in a soil or soilless substrate. Modifications to traditional limestone additions and fertility programs may also need to be tested and monitored to compensate for the biochar pH and mineral nutrient availability. Users should be aware that biochar products made from different feedstocks can have very different chemical properties even if the same process was used to manufacture them.}, number={1}, journal={HORTTECHNOLOGY}, author={Evans, Michael R. and Jackson, Brian E. and Popp, Michael and Sadaka, Sammy}, year={2017}, month={Feb}, pages={16–23} }
 @article{henry_mccall_jackson_whipker_2017, title={Growth Response of Herbaceous Ornamentals to Phosphorus Fertilization}, volume={52}, ISSN={["2327-9834"]}, DOI={10.21273/hortsci12256-17}, abstractNote={A series of experiments investigated the effects of increasing phosphate–phosphorus (P) concentrations on the growth and development of four horticultural species. In experiment 1, petunia [ Petunia atkinsiana (Sweet) D. Don ex W.H. Baxter] plants were grown using eight P concentrations, and we found that the upper bound for plant growth was at 8.72–9.08 mg·L −1 P, whereas concentrations ≤2.5 mg·L −1 P caused P deficiency symptoms. Experiment 2 investigated P growth response in two cultivars each of New Guinea impatiens ( Impatiens hawkeri W. Bull) and vinca [ Catharanthus roseus (L.) G. Don]. Growth for these plants was maximized with 6.43–12.42 mg·L −1 P. In experiment 3, ornamental peppers ( Capsicum annuum L. ‘Tango Red’) were given an initial concentration of P for 6 weeks and then switched to 0 mg·L −1 P to observe whether plants could be supplied with sufficient levels of P, and finished without P to keep them compact. Plants switched to restricted P began developing P deficiency symptoms within 3 weeks; however, restricting P successfully limited plant growth. These experiments indicated that current P fertilization regimens exceed the P requirements of these bedding plants, and depending on species, concentrations of 5–15 mg·L −1 P maximize growth.}, number={10}, journal={HORTSCIENCE}, author={Henry, Josh B. and McCall, Ingram and Jackson, Brian and Whipker, Brian E.}, year={2017}, month={Oct}, pages={1362–1367} }
 @article{blok_jackson_guo_visser_marcelis_2017, title={Maximum Plant Uptakes for Water, Nutrients, and Oxygen Are Not Always Met by Irrigation Rate and Distribution in Water-based Cultivation Systems}, volume={8}, ISSN={["1664-462X"]}, DOI={10.3389/fpls.2017.00562}, abstractNote={Growing on rooting media other than soils in situ –i.e. substrate-based growing- allows for higher yields than soil-based growing as transport rates of water, nutrients and oxygen in substrate surpass those in soil. Possibly water-based growing allows for even higher yields as transport rates of water and nutrients in water surpass those in substrate, even though the transport of oxygen may be more complex. Transport rates can only limit growth when they are below a rate corresponding to maximum plant uptake. Our first objective was to compare Chrysanthemum growth performance for three water-based growing systems with different irrigation. We compared; multi-point irrigation into a pond (DeepFlow); one-point irrigation resulting in a thin film of running water (NutrientFlow) and multi-point irrigation as droplets through air (Aeroponic). Second objective was to compare press pots as propagation medium with nutrient solution as propagation medium. The comparison included DeepFlow water-rooted cuttings with either the stem 1 cm into the nutrient solution or with the stem 1 cm above the nutrient solution. Measurements included fresh weight, dry weight, length, water supply, nutrient supply and oxygen levels. To account for differences in radiation sum received, crop performance was evaluated with Radiation Use Efficiency (RUE) expressed as dry weight over sum of Photosynthetically Active Radiation. The reference, DeepFlow with substrate-based propagation, showed the highest RUE, even while the oxygen supply provided by irrigation was potentially growth limiting. DeepFlow with water-based propagation showed 15-17% lower RUEs than the reference. NutrientFlow showed 8% lower RUE than the reference, in combination with potentially limiting irrigation supply of nutrients and oxygen. Aeroponic showed RUE levels similar to the reference and Aeroponic had non-limiting irrigation supply of water, nutrients and oxygen. Water-based propagation affected the subsequent cultivation in the DeepFlow negatively compared to substrate-based propagation. Water-based propagation resulted in frequent transient discolorations after transplanting in all cultivation systems, indicating a factor, other than irrigation supply of water, nutrients and oxygen, influencing plant uptake. Plant uptake rates for water, nutrients and oxygen are offered as a more fundamental way to compare and improve growing systems.}, journal={FRONTIERS IN PLANT SCIENCE}, author={Blok, Chris and Jackson, Brian E. and Guo, Xianfeng and Visser, Pieter H. B. and Marcelis, Leo F. M.}, year={2017}, month={Apr} }
 @article{judd_jackson_fonteno_domec_2016, title={Measuring root hydraulic parameters of container-grown herbaceous and woody plants using the hydraulic conductance flow meter}, volume={51}, number={2}, journal={HortScience}, author={Judd, L. A. and Jackson, B. E. and Fonteno, W. C. and Domec, J. C.}, year={2016}, pages={192–196} }
 @article{owen_jackson_whipker_fonteno_2016, title={Paclobutrazol drench activity not affected in sphagnum peat-based substrates amended with pine wood chip aggregates}, volume={26}, number={2}, journal={HortTechnology}, author={Owen, W. G. and Jackson, B. E. and Whipker, B. E. and Fonteno, W. C.}, year={2016}, pages={156–163} }
 @article{owen_jackson_whipker_fonteno_2016, title={Pine wood chips as an alternative to perlite in greenhouse substrates: Nitrogen requirements}, volume={26}, number={2}, journal={HortTechnology}, author={Owen, W. G. and Jackson, B. E. and Whipker, B. E. and Fonteno, W. C.}, year={2016}, pages={199–205} }
 @article{judd_jackson_fonteno_evans_boyette_2015, title={Changes in Root Growth and Physical Properties in Substrates Containing Charred or Uncharred Wood Aggregates (c)}, volume={1085}, ISSN={["2406-6168"]}, DOI={10.17660/actahortic.2015.1085.86}, journal={PROCEEDINGS OF THE 2014 ANNUAL MEETING OF THE INTERNATIONAL PLANT PROPAGATORS SOCIETY}, author={Judd, Lesley A. and Jackson, Brian E. and Fonteno, William C. and Evans, Michael R. and Boyette, Michael D.}, year={2015}, pages={421–425} }
 @article{judd_jackson_fonteno_2015, title={Rhizometer: An apparatus to observe and measure root growth and its effect on container substrate physical properties over time}, volume={50}, number={2}, journal={HortScience}, author={Judd, L. A. and Jackson, B. E. and Fonteno, W. C.}, year={2015}, pages={288–294} }
 @inproceedings{yap_jackson_fonteno_2015, title={Water retention of processed pine wood and pine bark and their particle size fractions ?}, volume={1085}, DOI={10.17660/actahortic.2015.1085.95}, booktitle={Proceedings of the 2014 annual meeting of the international plant propagators society}, author={Yap, T. C. and Jackson, B. E. and Fonteno, W. C.}, year={2015}, pages={467–471} }
 @inproceedings{kraus_pledger_riley_fonteno_jackson_bilderback_arboretum_2014, title={Defining rain garden filter bed substrates based on saturated hydraulic conductivity}, volume={1034}, booktitle={International symposium on growing media and soilless cultivation}, author={Kraus, H. and Pledger, R. and Riley, E. and Fonteno, W. C. and Jackson, B. E. and Bilderback, T. and Arboretum, J. C. R.}, year={2014}, pages={57–64} }
 @article{fields_fonteno_jackson_2014, title={Hydration efficiency of traditional and alternative greenhouse substrate components}, volume={49}, number={3}, journal={HortScience}, author={Fields, J. S. and Fonteno, W. C. and Jackson, B. E.}, year={2014}, pages={336–342} }
 @article{fields_fonteno_jackson_heitman_owen_2014, title={Hydrophysical properties, moisture retention, and drainage profiles of wood and traditional components for greenhouse substrates}, volume={49}, number={6}, journal={HortScience}, author={Fields, J. S. and Fonteno, W. C. and Jackson, B. E. and Heitman, J. L. and Owen, J. S.}, year={2014}, pages={827–832} }
 @article{judd_jackson_yap_fonteno_2014, title={Mini-horhizotron: An apparatus for observing and measuring root growth of container-grown plant material in situ}, volume={49}, number={11}, journal={HortScience}, author={Judd, L. A. and Jackson, B. E. and Yap, T. C. and Fonteno, W. C.}, year={2014}, pages={1424–1431} }
 @inproceedings{fields_fonteno_jackson_2014, title={Plant available and unavailable water in greenhouse substrates: Assessment and considerations}, volume={1034}, DOI={10.17660/actahortic.2014.1034.42}, booktitle={International symposium on growing media and soilless cultivation}, author={Fields, J. S. and Fonteno, W. C. and Jackson, B. E.}, year={2014}, pages={341–346} }
 @inproceedings{judd_jackson_fonteno_2014, title={Rhizometrics: A review of three in situ techniques for observation and measurement of plant root systems in containers}, volume={1034}, DOI={10.17660/actahortic.2014.1034.48}, abstractNote={Rhizometrics is a term derived from rhizo- (rhizosphere) and -metrics (series of parameters or measures of quantitative assessment used for measuring, comparisons or tracking performance or production), to describe several methods either developed or examined by North Carolina State University to observe and quantify root growth of plants in containers. Three new techniques have been developed and/or investigated as potential new methods of quantifying root growth; 1) Mini-Horhizotron; 2) Rhizometer; and 3) Hydraulic Conductance Flow Meter (HCFM). First, the mini-Horhizotrons have a clear, three-arm configuration suitable for observing root growth of small container plant material. The clear arms allow for visible access and measurements of plant roots. Potential measurements include root length, quantity of root hairs, and root architecture. Second, the Rhizometer is made from a clear cylinder that is 7.6 cm tall x 7.6 cm inside diameter, which allows for visible observations of root systems and they can be fitted in the North Carolina State University Porometer for in situ measurements of the influence of root growth on physical properties in containers during crop production. Thirdly, the HCFM is an apparatus that measures root and shoot conductance based on pressure and water flow through the roots, in the opposite direction of normal transpiration under quasi-steady-state conditions. Conductance values are directly indicative (and correlated) with root mass. These Rhizometric techniques are novel methods of observing and quantifying root growth and potentially identifying ways of improving root growth productivity and efficiency to maximize crop growth. These techniques have also been used to quantify root growth differences between/among various substrates. A summary of the initial experiments testing the usefulness of these three techniques for quantifying undisturbed root growth have yielded promising results.}, booktitle={International symposium on growing media and soilless cultivation}, author={Judd, L. A. and Jackson, B. E. and Fonteno, W. C.}, year={2014}, pages={389–397} }
 @inproceedings{fonteno_fields_jackson_2013, title={A pragmatic approach to wettability and hydration of horticultural substrates}, volume={1013}, DOI={10.17660/actahortic.2013.1013.15}, booktitle={International symposium on growing media, composting and substrate analysis}, author={Fonteno, W. C. and Fields, J. S. and Jackson, B. E.}, year={2013}, pages={139–146} }
 @article{judd_jackson_fonteno_2013, title={Novel Methods for Observing and Quantifying Root Growth of Horticultural Crops (c)}, volume={1014}, ISSN={["0567-7572"]}, DOI={10.17660/actahortic.2013.1014.88}, journal={PROCEEDINGS OF THE INTERNATIONAL PLANT PROPAGATORS' SOCIETY}, author={Judd, Lesley A. and Jackson, Brian E. and Fonteno, William C.}, year={2013}, pages={389–394} }
 @inproceedings{fields_jackson_fonteno_2013, title={Pine bark physical properties influenced by bark source and age (c)}, volume={1014}, DOI={10.17660/actahortic.2013.1014.96}, booktitle={Proceedings of the international plant propagators' society}, author={Fields, J. S. and Jackson, B. E. and Fonteno, W. C.}, year={2013}, pages={433–437} }
 @inproceedings{owen_jackson_fonteno_whipker_2013, title={Pine wood chips as an alternative to perlite: Cultural parameters to consider (c)}, volume={1014}, DOI={10.17660/actahortic.2013.1014.77}, booktitle={Proceedings of the international plant propagators' society}, author={Owen, W. G. and Jackson, B. E. and Fonteno, W. C. and Whipker, B. E.}, year={2013}, pages={345–349} }
 @inproceedings{yap_jackson_2013, title={Root growth of horticultural crops as influenced by pine bark age, wood, and sand amendment (c)}, volume={1014}, DOI={10.17660/actahortic.2013.1014.98}, booktitle={Proceedings of the international plant propagators' society}, author={Yap, T. C. and Jackson, B. E.}, year={2013}, pages={443–446} }
 @inproceedings{bilderback_riley_jackson_kraus_fonteno_owen_altland_fain_2013, title={Strategies for developing sustainable substrates in nursery crop production}, volume={1013}, DOI={10.17660/actahortic.2013.1013.2}, abstractNote={A comprehensive literature search of industrial and agricultural by-products to replace or extend existing soilless substrate components would produce a seemingly endless list of materials from “garbage” to a plethora of manure-based composts that have been tested both in the laboratory and in crop response studies throughout the world. Many of these alternatives have shown promise, but limiting factors for integration and use of the alternatives substrate components continue to include: regional or national availability; transport costs; handling costs; lack of a uniform and consistent product; guidelines for preparation and use of materials or impact on current crop production practices. If a product can overcome the above limitations, then researchers are tasked with documenting substrate physical or chemical characteristics. The objective in all studies is to maintain or increase growth of nursery crops and to extend the longevity and acceptable physical properties for long-term woody ornamental crops. Proof of results is determined using laboratory analyses and crop growth studies. Physiochemical properties are monitored over days, weeks, and months to ensure stability. Particle size distribution and varying ratios of substrate components are manipulated to achieve optimal air filled porosity and available water content. Soilless substrates are amended with lime, sulfur and nutrients or blended with other substrate components to provide optimal chemical characteristics. Additionally, substrates are evaluated under industry conditions to determine impact on water, nutrient and pest management to better understand obstacles to commercial adoption.}, booktitle={International symposium on growing media, composting and substrate analysis}, author={Bilderback, T. E. and Riley, E. D. and Jackson, B. E. and Kraus, Helen and Fonteno, W. C. and Owen, J. S. and Altland, J. and Fain, G. B.}, year={2013}, pages={43–56} }
 @article{jackson_wright_barnes_2010, title={Methods of Constructing a Pine Tree Substrate from Various Wood Particle Sizes, Organic Amendments, and Sand for Desired Physical Properties and Plant Growth}, volume={45}, ISSN={["2327-9834"]}, DOI={10.21273/hortsci.45.1.103}, abstractNote={The use of freshly harvested and processed pine trees as a container substrate for greenhouse and nursery crop production is a relatively new concept, and fundamental knowledge of the construction of a pine tree substrate (PTS) for optimal physical properties is insufficient. Therefore, this research was conducted to determine the influence of mixing PTSs produced with different wood particle sizes and adding other amendments to PTS on substrate physical properties and plant growth compared with traditional substrates. Coarse pine wood chips produced from 15-year-old loblolly pine trees ( Pinus taeda L.) were ground in a hammermill fitted with either a 4.76-mm screen or with no screen (PTS-NS) allowing a fine and a coarse particle PTS to be produced. Increasing proportions of the finer (4.76-mm) PTS to the coarser PTS (PTS-NS) resulted in increased container capacity (CC) and shoot growth of ‘Inca Gold’ marigold ( Tagetes erecta L.). In another study, PTSs were manufactured in a hammermill fitted with different screen sizes: 4.76, 6.35, 9.54, or 15.8 mm as well as PTS-NS. After being hammermilled, each of the five PTSs was then amended (by mixing) with 10% sand (PTS-S), 25% peatmoss (PTS-PM), or left unamended. Pine tree substrates were also produced by adding 25% aged pine bark (PB) to pine wood chips before being ground in a hammermill with each of the five screen sizes mentioned (PTS-HPB). These five substrates were used unamended as well as amended with 10% sand after grinding (PTS-HPBS). Control treatments included peat-lite (PL) and 100% aged PB for a total of 27 substrates evaluated in this study. Container capacity and marigold growth increased as screen size decreased and with the additions of peatmoss (PTS-PM) or hammering with PB (PTS-HPB) to PTS. Container capacity for all substrates amended with peatmoss or PB was within the recommended range of 45% to 65% for container substrates, but only with the more finely ground PTS-4.76-mm resulted in marigold growth comparable to PL and PB. However, when the PTS-NS was amended by mixing in 25% peat or hammering with 25% PB, growth of marigold was equal to plants grown in PL or PB. In a third study, hammering PTS-NS with 25% PB followed by the addition of 10% sand increased dry weight of both azalea ( Rhododendron × hybrida ‘Girard Pleasant White’) and spirea ( Spiraea nipponica Maxim. ‘Snowmound’) resulting in growth equal to plants grown in 100% PB. This work shows that amending coarsely ground PTS with finer particle PTS or with other materials (peatmoss, aged PB, or sand) can result in a substrate with comparable physical properties such as CC and plant growth compared with 100% PL or PB.}, number={1}, journal={HORTSCIENCE}, author={Jackson, Brian E. and Wright, Robert D. and Barnes, Michael C.}, year={2010}, month={Jan}, pages={103–112} }
 @article{jackson_wright_gruda_2009, title={Container Medium pH in a Pine Tree Substrate Amended with Peatmoss and Dolomitic Limestone Affects Plant Growth}, volume={44}, ISSN={["2327-9834"]}, DOI={10.21273/hortsci.44.7.1983}, abstractNote={This work was conducted to evaluate the effect of limestone additions to pine tree substrate (PTS) and PTS amended with peatmoss on pH and plant growth. ‘Inca Gold’ marigold ( Tagetes erecta L.) and ‘Rocky Mountain White’ geranium ( Pelargonium × hortorum L.H. Bailey) were grown in three PTSs—100% PTS, PTS plus 25% peatmoss (v/v), and PTS plus 50% peatmoss (v/v)—made from freshly harvested loblolly pine trees ( Pinus taeda L.) chipped and hammermilled through a 4.76-mm screen and a peatmoss/perlite (4:1 v/v; PL) control. Each substrate was amended with various rates of dolomitic limestone and used to grow marigolds in 10-cm square (l-L) plastic containers and geraniums in round 15-cm (1.25-L) plastic containers in a glasshouse. Regardless of limestone rate, pH was highest in 100% PTS and decreased with peat additions with PL having the lowest pH. As percent peat increased from 25% to 50%, more limestone was required to adjust pH to a particular level showing that PTS is more weakly buffered against pH change than peatmoss. Adding limestone did not increase the growth of marigold in 100% PTS, but additions of limestone did increase growth of marigold when grown in PTS containing peatmoss or in PL. Geranium growth was higher in PTS containing peatmoss (25% or 50%) and PL than in 100% PTS at all limestone rates. This research demonstrates that PTS produced from freshly harvested pine trees has an inherently higher pH than PL, and the additions of peatmoss to PTS require pH adjustment of the substrate for optimal plant growth.}, number={7}, journal={HORTSCIENCE}, author={Jackson, Brian E. and Wright, Robert D. and Gruda, Nazim}, year={2009}, month={Dec}, pages={1983–1987} }