@article{henry_veazie_furman_vann_whipker_2023, title={Spectral Discrimination of Macronutrient Deficiencies in Greenhouse Grown Flue-Cured Tobacco}, volume={12}, ISSN={["2223-7747"]}, DOI={10.3390/plants12020280}, abstractNote={Remote sensing of nutrient disorders has become more common in recent years. Most research has considered one or two nutrient disorders and few studies have sought to distinguish among multiple macronutrient deficiencies. This study was conducted to provide a baseline spectral characterization of macronutrient deficiencies in flue-cured tobacco (Nicotiana tabacum L.). Reflectance measurements were obtained from greenhouse-grown nutrient-deficient plants at several stages of development. Feature selection methods including information entropy and first and second derivatives were used to identify wavelengths useful for discriminating among these deficiencies. Detected variability was primarily within wavelengths in the visible spectrum, while near-infrared and shortwave-infrared radiation contributed little to the observed variability. Principal component analysis was used to reduce data dimensionality and the selected components were used to develop linear discriminant analysis models to classify the symptoms. Classification models for young, intermediate, and mature plants had overall accuracies of 92%, 82%, and 75%, respectively, when using 10 principal components. Nitrogen, sulfur, and magnesium deficiencies exhibited greater classification accuracies, while phosphorus and potassium deficiencies demonstrated poor or inconsistent results. This study demonstrates that spectral analysis of flue-cured tobacco is a promising methodology to improve current scouting methods.}, number={2}, journal={PLANTS-BASEL}, author={Henry, Josh and Veazie, Patrick and Furman, Marschall and Vann, Matthew and Whipker, Brian}, year={2023}, month={Jan} }
 @article{landis_hicks_mccall_henry_whipker_2021, title={Customizing the leaf tissue nutrient ranges for blue and pink hydrangeas}, ISSN={["1532-4087"]}, DOI={10.1080/01904167.2021.1952431}, abstractNote={Abstract Pink, blue, and red hydrangea [(Hydrangea macrophylla subsp. Macrophylla var. macrophylla (Thunb.)] cultivars contain the anthocyanin pigment delphinidin-3-glucoside that color the sepal. Without aluminum (Al), the natural color of the pigment is pink or red depending on the cultivar. To produce blue sepals, plants are fertilized with Al2(SO4)3 (AS) under low phosphorus (P) conditions. To determine the effect of AS on nutrient tissue concentrations ‘Early Blue’, ‘Hor Tivoli’, ‘Jip’, and ‘Mathilda Gutges’ plants were treated with 0 (pink), 12, or 15 g (blue) of AS. Pre-bloom leaf tissue concentrations were analyzed with blue cultivars generally having higher concentrations of sulfur (S), iron (Fe), manganese (Mn), zinc (Zn), boron (B), copper (Cu), and Al, while the pink plants had higher nitrogen (N), P, calcium (Ca), and magnesium (Mg) concentrations. Concentrations of N, potassium (K), Mg, B and Cu were consistent with published sufficiency ranges regardless of color or cultivar, while S, Fe, Mn and Zn concentrations were below sufficiency in some pink cultivars. The P concentrations in both pink and blue cultivars and Ca in some blue cultivars were lower than the published sufficiency range. The difference in leaf tissue nutrient concentrations among cultivars and coloration, suggest that nutrient uptake in hydrangeas varies and that lab recommendations should be customized depending on cultivar and color production system.}, journal={JOURNAL OF PLANT NUTRITION}, author={Landis, Hunter and Hicks, Kristin and McCall, Ingram and Henry, Josh B. and Whipker, Brian E.}, year={2021}, month={Jul} }
 @article{landis_hicks_mccall_henry_whipker_2021, title={Enhancing blue hydrangea sepal coloration by applying aluminum sulfate through constant liquid fertilization}, volume={1305}, ISSN={["2406-6168"]}, DOI={10.17660/ActaHortic.2021.1305.60}, journal={III INTERNATIONAL SYMPOSIUM ON GROWING MEDIA, COMPOSTING AND SUBSTRATE ANALYSIS}, author={Landis, H. and Hicks, K. and McCall, I and Henry, J. B. and Whipker, B. E.}, year={2021}, pages={455–461} }
 @article{veazie_cockson_henry_perkins-veazie_whipker_2020, title={Characterization of Nutrient Disorders and Impacts on Chlorophyll and Anthocyanin Concentration of Brassica rapa var. Chinensis}, volume={10}, ISSN={["2077-0472"]}, DOI={10.3390/agriculture10100461}, abstractNote={Essential plant nutrients are needed at crop-specific concentrations to obtain optimal growth and yield. Foliar tissue analysis is the standard method for assessing nutrient levels in plants. Symptoms of nutrient deficiency or toxicity occur when the foliar tissue values become too low or high. Diagnostic nutrient deficiency criteria for Brassica rapa var. Chinensis (bok choy) is lacking in the current literature. In this study, green (‘Black Summer’) and purple (‘Red Pac’) bok choy plants were grown in silica sand culture, with control plants receiving a complete modified Hoagland’s all-nitrate solution, and nutrient-deficient plants induced by using a complete nutrient formula withholding a single nutrient. Tissue samples were collected at the first sign of visual disorder symptoms and analyzed for dry weight and nutrient concentrations of all plant essential elements. Six weeks into the experiment, the newest matured leaves were sampled for chlorophyll a, b, and total carotenoids concentrations for both cultivars, and total anthocyanin concentration in ‘Red Pac’. Compared to control plants, the dry weight of ‘Black Summer’ green bok choy was significantly lower for nitrogen (N), phosphorus (P), calcium (Ca), or boron (B) deficiency treatments, and nutrient concentrations were lower for all variables except iron (Fe) deficiency. Dry weight was less in ‘Red Pac’ plants grown without N, potassium (K), Ca, B, or molybdenum (Mo), and nutrient concentrations were lower for all except Mo-deficiency compared to controls. Total chlorophyll and total carotenoid concentrations were lower in leaves from N−, Fe-, and manganese- (Mn) deficient plants of both cultivars. Leaf anthocyanin concentration was lower only for K-, Ca-, and B-deficiencies in ‘Red Pac’. Our results indicate that visual symptoms of nutrient deficiency are well correlated with nutrient disorders. In contrast, changes in dry weight, chlorophyll, and anthocyanin did not show consistent changes across nutrient disorders.}, number={10}, journal={AGRICULTURE-BASEL}, author={Veazie, Patrick and Cockson, Paul and Henry, Josh and Perkins-Veazie, Penelope and Whipker, Brian}, year={2020}, month={Oct} }
 @article{montgomery_henry_vann_whipker_huseth_mitasova_2020, title={Measures of Canopy Structure from Low-Cost UAS for Monitoring Crop Nutrient Status}, volume={4}, ISSN={2504-446X}, url={http://dx.doi.org/10.3390/drones4030036}, DOI={10.3390/drones4030036}, abstractNote={Deriving crop information from remotely sensed data is an important strategy for precision agriculture. Small unmanned aerial systems (UAS) have emerged in recent years as a versatile remote sensing tool that can provide precisely-timed, fine-grained data for informing management responses to intra-field crop variability (e.g., nutrient status and pest damage). UAS sensors with high spectral resolution used to compute informative vegetation indices, however, are practically limited by high cost and data dimensionality. This research extends spectral analysis for remote crop monitoring to investigate the relationship between crop health and 3D canopy structure using low-cost UAS equipped with consumer-grade RGB cameras. We used flue-cured tobacco as a case study due to its known sensitivity to fertility variation and nutrient-specific symptomology. Fertilizer treatments were applied to induce plant health variability in a 0.5 ha field of flue-cured tobacco. Multi-view stereo images from three UAS surveys collected during crop development were processed into orthoimages used to compute a visible band spectral index and photogrammetric point clouds using Structure from Motion (SfM). Plant structural metrics were then computed from detailed high resolution canopy surface models (0.05 m resolution) interpolated from the photogrammetric point clouds. The UAS surveys were complimented by nutrient status measurements obtained from plant tissues. The relationships between foliar nitrogen (N), phosphorus (P), potassium (K), and boron (B) concentrations and the UAS-derived metrics were assessed using multiple linear regression. Symptoms of N and K deficiencies were well captured and differentiated by the structural metrics. The strongest relationship observed was between canopy shape and N foliar concentration (adj. r2 = 0.59, increasing to adj. r2 = 0.81 when combined with the spectral index). B foliar concentration was consistently better predicted by canopy structure with a maximum adj. r2 = 0.41 observed at the latest growth stage surveyed. Overall, combining information about canopy structure and spectral reflectance increased model fit for all measured nutrients compared to spectral alone. These results suggest that an important relationship exists between relative canopy shape and crop health that can be leveraged to improve the usefulness of low cost UAS for precision agriculture.}, number={3}, journal={Drones}, publisher={MDPI AG}, author={Montgomery, Kellyn and Henry, Josh and Vann, Matthew and Whipker, Brian E. and Huseth, Anders and Mitasova, Helena}, year={2020}, month={Jul}, pages={36} }
 @misc{henry_vann_lewis_2019, title={Agronomic Practices Affecting Nicotine Concentration in Flue-Cured Tobacco: A Review}, volume={111}, ISSN={["1435-0645"]}, DOI={10.2134/agronj2019.04.0268}, abstractNote={Proposed regulations mandating lower nicotine concentrations in tobacco (Nicotiana tabacum L.) products will likely require changes in tobacco production to reduce nicotine while maintaining yield and quality. The agronomic practices used for tobacco production have a significant impact on the synthesis and accumulation of nicotine in flue‐cured tobacco. Nicotine is the primary alkaloid in flue‐cured tobacco and is one of the main reasons for its commercial production. Most agronomic practices that improve plant health and yield have a positive effect on nicotine production and accumulation. Some of the most important factors that affect nicotine concentrations are N fertilization, planting density, topping practices, sucker control, and harvesting practices. The amount of N available to the plant has a substantial effect on nicotine, as N is a primary component of the nicotine molecule. Factors leading to higher N uptake lead to higher nicotine concentrations. Plant and leaf densities within the field also have a significant effect on nicotine, where increasing densities leads to lower nicotine concentrations. Flowering and sucker production are both significant sinks of energy and other resources. Eliminating the inflorescence via topping and controlling suckers lead to higher nicotine concentrations. In fact, substantial nicotine synthesis and accumulation occurs in the days and weeks following topping. This comprehensive review discusses the agronomic factors affecting alkaloid production in flue‐cured tobacco, and how these factors can be adjusted to manipulate the ultimate nicotine concentration.}, number={6}, journal={AGRONOMY JOURNAL}, author={Henry, Josh B. and Vann, Matthew C. and Lewis, Ramsey S.}, year={2019}, pages={3067–3075} }
 @article{landis_hicks_cockson_henry_smith_whipker_2019, title={Expanding Leaf Tissue Nutrient Survey Ranges for Greenhouse Cannabidiol-Hemp}, volume={5}, ISSN={["2374-3832"]}, DOI={10.2134/cftm2018.09.0081}, abstractNote={Core Ideas Leaf tissue nutrient concentration survey values do not exist for greenhouse CBD-hemp. Growers can use these ranges as a nutrient management tool for CBD-hemp stock plants. Different leaf tissue nutrient concentrations have been found in CBD-hemp cultivars. There are no researched nutrient recommendations specific to greenhouse CBD-hemp. CBD-hemp products have great market potential.}, number={1}, journal={CROP FORAGE & TURFGRASS MANAGEMENT}, author={Landis, Hunter and Hicks, Kristin and Cockson, Paul and Henry, Josh B. and Smith, James T. and Whipker, Brian E.}, year={2019}, month={Jan} }
 @article{henry_perkins-veazie_mccall_whipker_2019, title={Restricted Phosphorus Fertilization Increases the Betacyanin Concentration and Red Foliage Coloration of Alternanthera}, volume={144}, ISSN={["2327-9788"]}, DOI={10.21273/JASHS04702-19}, abstractNote={Phosphorus (P) deficiency commonly results in the development of red-to-purple coloration in plant foliage, typically attributed to anthocyanins. Betacyanins are a red pigment found in some plant species that do not produce anthocyanins, including Alternanthera sp. This study was conducted to investigate the effects of P nutrition on the betacyanin concentration and subsequent foliar coloration of ‘Purple Prince’, ‘Brazilian Red Hots’, and ‘Little Ruby’ alternanthera (Alternanthera brasiliana). The purpose of this study was to determine whether P fertilization management could enhance the coloration and aesthetic appeal of alternanthera. Custom fertilizers provided P concentrations of 0, 2.5, 5, 10, and 20 mg·L−1 P. One-half of the plants from each P concentration were restricted to 0 mg·L−1 P 1 month after transplant to determine whether adequate size could be attained before withholding P. Differences in P response were observed among cultivars for hue, betacyanin content, and plant size. Concentrations ≤5 mg·L−1 P resulted in plants that were more compact in terms of plant height and diameter, had deeper red foliage coloration, and greater foliar betacyanins compared with plants grown with greater P concentrations. Plants initially grown with 5 or 10 mg·L−1 P attained marketable size before P restriction and developed more red pigmentation compared with plants grown with P for the remaining duration of the study. Regression analysis demonstrated height was maximized with 3 to 8 mg·L−1 P, diameter with 4.1 to 8.4 mg·L−1 P, and branching with 10.0 mg·L−1 P. Foliar betacyanin concentrations were greatest in plants grown without P, reaching 269 mg/100 g fresh weight, whereas plants grown with 10 or 20 mg·L−1 P were 95% less (averaged ≈13 mg/100 g fresh weight). This study demonstrates that P restriction can benefit the aesthetic appeal of alternanthera and provides the first confirmation that P nutrition is associated with betacyanin accumulation.}, number={4}, journal={JOURNAL OF THE AMERICAN SOCIETY FOR HORTICULTURAL SCIENCE}, author={Henry, Josh B. and Perkins-Veazie, Penelope and McCall, Ingram and Whipker, Brian E.}, year={2019}, month={Jul}, pages={264–273} }
 @article{henry_vann_mccall_cockson_whipker_2018, title={Nutrient Disorders o Burley and Flue-Cured Tobacco: Part 1-Macronutrient Deficiencies}, volume={4}, ISSN={["2374-3832"]}, DOI={10.2134/cftm2017.11.0076}, abstractNote={Core Ideas
Recognizing macronutrient disorders is important for commercial production.
Foliar nutrient concentrations were identified for burley and flue‐cured tobacco.
Symptoms and critical values were compared with published results.
}, number={1}, journal={CROP FORAGE & TURFGRASS MANAGEMENT}, publisher={American Society of Agronomy}, author={Henry, Josh B. and Vann, Matthew and McCall, Ingram and Cockson, Paul and Whipker, Brian E.}, year={2018}, month={Mar} }
 @article{henry_vann_mccall_cockson_whipker_2018, title={Nutrient Disorders of Burley and Flue-Cured Tobacco: Part 2-Micronutrient Disorders}, volume={4}, ISSN={["2374-3832"]}, DOI={10.2134/cftm2017.11.0077}, abstractNote={Core Ideas
Recognizing micronutrient disorders is important for commercial production.
Unique, previously unobserved nutrient disorder symptoms were observed.
Foliar nutrient concentrations were identified for burley and flue‐cured tobacco.
Symptoms and critical values were compared with published results.
}, number={1}, journal={CROP FORAGE & TURFGRASS MANAGEMENT}, publisher={American Society of Agronomy}, author={Henry, Josh B. and Vann, Matthew and McCall, Ingram and Cockson, Paul and Whipker, Brian E.}, year={2018}, month={Mar} }
 @article{henry_mccall_whipker_2018, title={Phosphorus Restriction as an Alternative to Chemical Plant Growth Retardants in Angelonia and New Guinea Impatiens}, volume={28}, ISSN={["1943-7714"]}, DOI={10.21273/horttech03939-17}, abstractNote={Chemical plant growth retardants (PGRs) are commonly used to produce compact bedding plants. Few PGRs are labeled for sensitive species because of the concern of excessive restriction of stem elongation or phytotoxicity. Growers are therefore presented with a dilemma: produce untreated plants that may be too tall or risk applying a PGR that can potentially lead to irreversible aesthetic damage to the plant. Nutrient restriction, specifically of phosphorus (P), may be used to control plant height. This study was conducted to determine if restricting P fertilization yielded comparable growth control to plants produced with PGRs. Two cultivars each of new guinea impatiens (Impatiens hawkeri) and angelonia (Angelonia angustifolia) were grown using five fertilizers that varied by P concentration (0, 2.5, 5, 10, and 20 ppm). Half of the plants from each P fertilizer concentration were treated with paclobutrazol at 4 and 5 weeks after transplant for angelonia and new guinea impatiens, respectively. On termination of the experiment, data were collected for height, diameter, and dry weight, which were used to determine a growth index (GI). Angelonia GI values were maximized with 7–9 ppm P, whereas new guinea impatiens GI was maximized with 8–11 ppm P. Concentrations of 3–5 ppm P provided similar height control to plants grown with nonlimiting P and a paclobutrazol application. Concentrations of ≤2.5 ppm P resulted in low-quality plants with visual symptoms of P deficiency. These results indicate that a narrow range of P concentrations may be used to control stem elongation and keep plants compact.}, number={2}, journal={HORTTECHNOLOGY}, author={Henry, Josh B. and McCall, Ingram and Whipker, Brian E.}, year={2018}, month={Apr}, pages={136–142} }
 @article{henry_mccall_nelson_whipker_2018, title={Source-sink interactions lead to atypical reproductive stage phosphorus deficiency symptoms on the upper foliage of Capsicum annuum and Chrysanthemum x morifolium}, volume={238}, ISSN={["1879-1018"]}, DOI={10.1016/j.scienta.2018.04.069}, abstractNote={Phosphorus (P) restriction has become more prevalent in floriculture production to control growth and reduce fertilizer waste. With low P fertilization practices, growers are more likely to develop P deficiency in their crops. Symptoms of a reproductive stage P deficiency were reported in which symptomology occurs on the foliage directly below the flowers or fruit. To induce and describe these symptoms, ornamental peppers (Capsicum annuum L.) and chrysanthemums (Chrysanthemum ×morifolium Ramat.) were grown initially with P fertilization, but half the plants were later restricted to 0 mg L−1 P upon floral initiation. Plants that were P restricted developed symptoms of chlorosis, olive green spotting, and necrosis on the upper foliage below the reproductive structures, while central foliage remained asymptomatic. ‘Crystal Misty Purple’ chrysanthemums developed unique symptoms of upper leaf purpling. Phosphorus movement within the plant was quantified via tissue division and analysis. The highest tissue P concentrations were in the flowers or fruit for both species, regardless of symptoms. Up to 80% of the total P in aboveground tissues was in the flowers and fruit of symptomatic plants. Vegetative tissue P concentrations were significantly lower in symptomatic plants compared to the asymptomatic controls, indicating that large quantities of P were translocated from vegetative tissues to the developing reproductive tissues. Remobilized P from the lower tissues appeared to bypass the upper foliage in favor of the flowers and fruit. Thus, the developing upper foliage was deprived of P, leading to P deficiency symptoms due to competition with the maturing flowers and fruit.}, journal={SCIENTIA HORTICULTURAE}, author={Henry, Josh B. and McCall, Ingram and Nelson, Paul V. and Whipker, Brian E.}, year={2018}, month={Aug}, pages={288–294} }
 @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} }