@article{park_collado_lam_hernandez_2023, title={Flowering Response of Cannabis sativa L. 'Suver Haze' under Varying Daylength-Extension Light Intensities and Durations}, volume={9}, ISSN={["2311-7524"]}, DOI={10.3390/horticulturae9050526}, abstractNote={Daylength-extension lighting (DE) is used in the cannabis industry to increase plant size and produce cuttings by regulating flowering and extending the vegetative stage. Growers have reported incomplete or transitional inflorescences in several Cannabis cultivars even when exposed to long photoperiods. Cannabis sativa L. ‘Suver Haze’ has been reported to develop incomplete inflorescences in North Carolina nurseries using photoperiods of 15 h. The objectives of this study were to investigate the required light intensity and photoperiod to inhibit the flowering of ‘Suver Haze’. In Experiment 1, DE of 1.0, 2.5, 5.8, and 10.3 µmol·m−2·s−1 of photosynthetic photon flux density from incandescent lamps were used to extend the photoperiod of ‘Suver Haze’ from 9 to 15 h. A 9 h photoperiod control was included. The results showed that all DE treatments stopped the full transition to flowering compared to the control; however, all DE-treated plants showed the presence of incomplete inflorescences. In Experiment 2, three photoperiod treatments of 15 h, 18 h, and 21 h were tested. ‘Suver Haze’ under 18 h and 21 h photoperiods did not develop incomplete inflorescences in contrast to plants in 15 h photoperiod. Therefore, a light intensity of at least 1.0 µmol·m−2·s−1 PPFD and an 18 h photoperiod are required to prevent incomplete inflorescences and flowering of ‘Suver Haze’.}, number={5}, journal={HORTICULTURAE}, author={Park, Jongseok and Collado, Cristian E. E. and Lam, Vu Phong and Hernandez, Ricardo}, year={2023}, month={Apr} }
 @article{collado_hernandez_2022, title={Effects of Light Intensity, Spectral Composition, and Paclobutrazol on the Morphology, Physiology, and Growth of Petunia, Geranium, Pansy, and Dianthus Ornamental Transplants}, volume={41}, ISSN={["1435-8107"]}, url={https://doi.org/10.1007/s00344-021-10306-5}, DOI={10.1007/s00344-021-10306-5}, number={2}, journal={JOURNAL OF PLANT GROWTH REGULATION}, publisher={Springer Science and Business Media LLC}, author={Collado, Cristian E. and Hernandez, Ricardo}, year={2022}, month={Feb}, pages={461–478} }
 @article{lam_hernandez_lee_kim_park_2022, title={Generation of Adventitious Roots and Characteristics of Gas Exchange according to Leaf Number of Hemp (Cannabis sativa L.) Cuttings}, volume={40}, ISSN={["2465-8588"]}, DOI={10.7235/HORT.20220004}, abstractNote={In the hemp-seedling industry, the number of leaves on the harvested cuttings from mother plants is crucial for survival. Therefore, the present study determined the suitable number of leaves on hemp (Cannabis sativa L.) cuttings to promote adventitious root (AR) formation. Hemp cuttings with two, three, and four leaves were harvested from the apex of the mother plant. After disinfecting their base, 18 cuttings per replication were transplanted into a plug tray (72 holes) filled with a horticultural substrate. The photosynthetic characteristics of the cuttings and well-rooted hemp plants were measured at 22 and 60 days after transplantation (DAT), respectively. At 22 DAT, the average AR length, AR fresh weight, AR generation rate, and average number of ARs were the highest from two-leaf cuttings. Due to the higher AR generation, the net photosynthetic rate was the highest in cuttings with two-leaf cuttings at all the light intensity conditions (0, 50, 100, 175, 250, 500, 750, 1,000, and 1,500 μmol·m-2·s-1). The initial AR development of cuttings with two leaves likely enabled sufficient water uptake and photosynthesis to increase the survival rate. Growers may increase the productivity per unit area of well-rooted hemp plants by harvesting cuttings with two leaves. Additional key words: fresh weight, light intensity, net photosynthetic rate, root quality, well-rooted hemp plant}, number={1}, journal={HORTICULTURAL SCIENCE & TECHNOLOGY}, author={Lam, Vu Phong and Hernandez, Ricardo and Lee, Jeongyeo and Kim, Sung Jin and Park, Jongseok}, year={2022}, pages={30–38} }
 @article{huber_louws_hernandez_2021, title={Impact of Different Daily Light Integrals and Carbon Dioxide Concentrations on the Growth, Morphology, and Production Efficiency of Tomato Seedlings}, volume={12}, ISSN={["1664-462X"]}, url={http://dx.doi.org/10.3389/fpls.2021.615853}, DOI={10.3389/fpls.2021.615853}, abstractNote={Indoor growing systems with light-emitting diodes offer advantages for the growth of tomato seedlings through uniform and optimized environmental conditions which increase consistency between plants and growing cycles. CO2 enrichment has been shown to improve the yield of crops. Thus, this research aimed to characterize the effects of varied light intensities and CO2 enrichment on the growth, morphology, and production efficiency of tomato seedlings in indoor growing systems. Four tomato cultivars, “Florida-47 R,” “Rebelski,” “Maxifort,” and “Shin Cheong Gang,” were subjected to three different daily light integrals (DLIs) of 6.5, 9.7, and 13 mol m–2 d–1 with a percent photon flux ratio of 40 blue:60 red and an end-of-day far-red treatment of 5 mmol m–2 d–1. The plants were also subjected to three different CO2 concentrations: 448 ± 32 (400-ambient), 1010 ± 45 (1000), and 1568 ± 129 (1600) μmol mol–1. Temperature was maintained at 24.3°C ± 0.48/16.8°C ± 1.1 (day/dark; 22.4°C average) and relative humidity at 52.56 ± 8.2%. Plant density was 1000 plants m–2 until canopy closure. Morphological measurements were conducted daily to observe the growth response over time. In addition, data was collected to quantify the effects of each treatment. The results showed increases in growth rate with increases in the DLI and CO2 concentration. In addition, CO2 enrichment to 1000–1600 μmol mol–1 increased the light use efficiency (gDM mol–1 applied) by 38–44%, and CO2 enrichment to 1600 μmol mol–1 did not result in any additional increase on shoot fresh mass, shoot dry mass, and stem extension. However, the net photosynthetic rate obtained with 1600 μmol mol–1 was 31 and 68% higher than those obtained with 1000 and 400 μmol mol–1, respectively. Furthermore, the comparison of the light and CO2 treatment combinations with the control (13 mol m–2 d–1–400CO2) revealed that the plants subjected to 6.5DLI–1600CO2, 9.7DLI–1000CO2, and 9.7DLI–1600CO2 treatment combinations exhibited the same growth rate as the control plants but with 25–50% less DLI. Furthermore, two treatment combinations (13.0DLI–1000CO2 and 13.0DLI–1600CO2) were associated with the consumption of comparable amount of energy but increased plant growth by 24–33%.}, journal={FRONTIERS IN PLANT SCIENCE}, publisher={Frontiers Media SA}, author={Huber, Brandon M. and Louws, Frank J. and Hernandez, Ricardo}, year={2021}, month={Mar} }
 @article{shi_hernandez_hoffmann_2021, title={Impact of Nitrate and Ammonium Ratios on Flowering and Asexual Reproduction in the Everbearing Strawberry Cultivar Fragaria x ananassa Albion}, volume={7}, ISSN={["2311-7524"]}, DOI={10.3390/horticulturae7120571}, abstractNote={Ever-bearing (EB) strawberries are long-day cultivars that show perpetual flowering behavior. Compared to June-bearing short-day cultivars, EB cultivars can initiate flowers with less dependency on light and temperature levels. This leads to a more consistent flowering and fruiting pattern, making EB cultivars favorable for areas with long growing seasons. However, this flowering pattern also brings significant challenges to open-field strawberry nurseries. Consistent flower development in EB cultivars frequently leads to increased labor cost for manual flower removal on nursery ground. The alteration of flowering behavior via fertilizer regimes could be a cost-effective tool for strawberry nurseries. However, while it is known that the source of nitrogen (N) impacts strawberry flowering, its effect on strawberry propagation rates needs further investigation. The objective of this study was to investigate the impact of nitrate (NO3−) to ammonium (NH4+) ratio on flower and daughter plant production in the EB strawberry cultivar ‘Albion’ (Fragaria × ananassa c.v. ‘Albion’). Strawberry plants were grown in a completely randomized design under greenhouse conditions (26.6 °C, 16 h photoperiod). Four treatments of NO3−:NH4+ were implemented: (1) 100%:0%; (2) 80%:20%; (3) 60%:40%; (4) 50%:50%. Strawberry plants fertilized with a 60%:40% NO3−:NH4+ ratio produced 17–31% fewer inflorescences than those fertilized with 100%:0% (8.8 ± 1.19) and 80%:20% (10.3 ± 1.85) ratios. The production of daughter plants remained similar in all four treatments. Our results show that increased ratios of ammonium in combination with decreased ratios of nitrate reduce flowering of EB strawberry cultivars, while propagation rates remain consistent. These results could potentially lead to the development of fertilizer regimes for strawberry nurseries to reduce flower production in EB cultivars.}, number={12}, journal={HORTICULTURAE}, author={Shi, Xiaonan and Hernandez, Ricardo and Hoffmann, Mark}, year={2021}, month={Dec} }
 @article{huber_hernandez_2021, title={Optimizing production of 'Fascination' and 'Carnivor' transplants for grafting using lower daily light integral and higher CO2}, volume={1302}, ISSN={["2406-6168"]}, DOI={10.17660/ActaHortic.2021.1302.14}, journal={II INTERNATIONAL SYMPOSIUM ON VEGETABLE GRAFTING}, author={Huber, B. and Hernandez, R.}, year={2021}, pages={103–109} }
 @article{ranieri_sponsel_kizer_rojas‐pierce_hernández_gatiboni_grunden_stapelmann_2021, title={Plasma agriculture: Review from the perspective of the plant and its ecosystem}, url={https://doi.org/10.1002/ppap.202000162}, DOI={10.1002/ppap.202000162}, abstractNote={Abstract Plasma agriculture details the role of nonthermal plasma in the development of plants from seeds to crops. Several publications reported enhanced plant growth, improved stress tolerance, and antimicrobial effects of plasma treatment and plasma‐treated water. In this review, we present an overview of the recent plasma agriculture literature and put it in the context of the plant needs and the effects on the plant ecosystem. We will discuss key developmental stages of plants and their needs, the different growth environments from hydroponics to soilless and soil substrates, and the plant microbiome. This review provides the context to design plasma‐based fertilization strategies to address the needs of plants and their ecosystem.}, journal={Plasma Processes and Polymers}, author={Ranieri, Pietro and Sponsel, Nicholas and Kizer, Jon and Rojas‐Pierce, Marcela and Hernández, Ricardo and Gatiboni, Luciano and Grunden, Amy and Stapelmann, Katharina}, year={2021}, month={Jan} }
 @article{shi_hernandez_hoffmann_2021, title={The influence of stolon harvest frequency and nitrate: ammonium ratio on asexual reproduction of day-neutral strawberries (Fragaria xananassa 'Albion')}, volume={1309}, ISSN={["2406-6168"]}, DOI={10.17660/ActaHortic.2021.1309.41}, journal={IX INTERNATIONAL STRAWBERRY SYMPOSIUM}, author={Shi, X. and Hernandez, R. and Hoffmann, M.}, year={2021}, pages={283–288} }
 @article{shi_hernandez_hoffmann_2021, title={Timing of Stolon Removal Alters Daughter Plant Production and Quality in the Ever-bearing Strawberry 'Albion'}, volume={56}, ISSN={["2327-9834"]}, DOI={10.21273/HORTSCI15624-20}, abstractNote={Commercial strawberry (Fragaria ×ananassa Duch.) plants propagate through the development of stolons (runners) with attached daughter plants. While it is known that temperature and photoperiod affect strawberry propagation, little knowledge exists on whether cultural methods may influence stolon and daughter plant development. The objective of this study was to characterize the impact of three stolon removal treatments on the development of daughter plants in the ever-bearing strawberry ‘Albion’. Treatments included 1) stolon removal every 7 days, nine times total; 2) stolon removal every 21 days, three times total; and 3) one-time stolon removal after 63 days. Strawberry plants were grown in a controlled environment (26 °C, 507 μmol⋅m–2⋅s–1 photosynthetic photon flux density, 14-hour photoperiod) in soilless media and fertilized with a customized nutrient solution. Mother plants in the 63-day treatment produced more daughter plants (102 per plant), than in the 21-day treatment (33 per plant) and the 7-day treatment (16 per plant). In the 63-day treatment, daughter plants and stolons accumulated to 86.6% of the total biomass, to 42.9% in the 7-day treatment and to 60.6% of total biomass in the 21-day treatment. Mother plant organs (including roots, crown, and leaves) had less dry weight in the 63-day treatment compared with the 7-day treatment and 21-day treatment, respectively. Furthermore, the daughter plants produced at the 63-day treatment had smaller crown diameters (0.65 cm) and less dry weight (0.51 g) and a higher number of fully expanded leaves (2.9) and visible roots (13.4) compared with the 21-day treatment and the 7-day treatment. The results of this study show daughter plant production of strawberry plants declines significantly with shorter stolon removal intervals, indicating the need to adjust stolon removal in strawberry nurseries for optimal daughter plant production.}, number={6}, journal={HORTSCIENCE}, author={Shi, Xiaonan and Hernandez, Ricardo and Hoffmann, Mark}, year={2021}, month={Jun}, pages={650–656} }
 @article{spalholz_perkins-veazie_hernandez_2020, title={Impact of sun-simulated white light and varied blue:red spectrums on the growth, morphology, development, and phytochemical content of green-and red-leaf lettuce at different growth stages}, volume={264}, ISSN={["1879-1018"]}, DOI={10.1016/j.scienta.2020.109195}, abstractNote={Light drives photosynthesis and regulates plant morphology, physiology, and phytochemical content. Using light emitting diodes (LEDs), customized spectra can be created, including spectrum that simulates solar light. The aim of this study was to assess the growth, development, and phytochemical content at three marketable stages of lettuce (transplant, baby-leaf, and head-lettuce) under a sun-simulated spectrum and common light spectra used in indoor growing systems. Oakleaf red (Salanova® 'Red Oakleaf') and green (Salanova® 'Green Oakleaf') lettuce were grown under seven spectra. A sun-simulated light treatment (SUN) was created with 5 % ultraviolet-A (UV-A), 20 % blue (B), 26 % green (G), 26 % red (R), and 23 % far-red (FR) light as percent photon flux density (PFD). In addition, five treatments of differing blue:red (B:R) ratios were evaluated: 0B:100R (100R), 20B:80R, 50B:50R, 80B:20R, and 100B:0R (100B) and fluorescent white light was used as a control (6500 K). Plants were provided with 200 ± 0.7 μmol·m−2·s−1 biologically active radiation (300–800 nm) for 18 h and grown at 20.0 ± 0.2 °C temperature. Fresh mass of lettuce in the SUN treatment was not significantly different when compared to B:R light treatments in all harvest dates despite the 36 % greater photosynthetic photon flux density (PPFD) in B:R treatments. Plant dry mass on day 17 of' Green Oakleaf' and 'Red Oakleaf' grown under 20B:80R was 15–39 % greater than those grown in 100B and SUN. When calculating total dry mass accumulation to cumulative yield photon flux density (YPFD), plants in SUN treatment accumulated the same dry mass per YPFD input (mg mol−1). Leaf area at day 42 of plants in 100B, SUN, and FL was 39–78 % greater than plants in B:R treatments. At final harvest (day 42), plant stem length in SUN was 2.1–4.4 times longer than in all other treatments, indicating bolting and flowering initiation. Both total phenolic and anthocyanin concentrations were greater in the B:R treatments than in SUN, 100R, and 100B treatments. This study presents baseline information for lettuce responses under LED-simulated SUN spectrum when compared to common B:R treatments and offers insights on lettuce growth and morphology under different spectra at multiple growth stages.}, journal={SCIENTIA HORTICULTURAE}, author={Spalholz, Hans and Perkins-Veazie, Penelope and Hernandez, Ricardo}, year={2020}, month={Apr} }
 @article{kotilainen_aphalo_brelsford_book_devraj_heikkila_hernandez_kylling_lindfors_robson_2020, title={Patterns in the spectral composition of sunlight and biologically meaningful spectral photon ratios as affected by atmospheric factors}, volume={291}, ISSN={["1873-2240"]}, DOI={10.1016/j.agrformet.2020.108041}, abstractNote={Plants rely on spectral cues present in their surroundings, generated by the constantly changing light environment, to guide their growth and reproduction. Photoreceptors mediate the capture of information by plants from the light environment over a wide range of wavelengths, but despite extensive evidence that plants respond to various light cues, only fragmentary data have been published showing patterns of diurnal, seasonal and geographical variation in the spectral composition of daylight. To illustrate patterns in spectral photon ratios, we measured time series of irradiance spectra at two distinct geographical and climatological locations, Helsinki, Finland and Gual Pahari, India. We investigated the drivers behind variation of the spectral photon ratios measured at these two locations, based on the analysis of over 400 000 recorded spectra. Differences in spectral irradiance were explained by different atmospheric factors identified through multiple regression model analysis and comparison to spectral irradiance at ground level simulated with a radiative transfer model. Local seasonal and diurnal changes in spectral photon ratios were related to solar elevation angle, atmospheric water-vapour content and total ozone column thickness and deviated from their long-term averages to an extent likely to affect plant photobiology. We suggest that future studies should investigate possible effects of varying photon ratios on terrestrial plants. Solar elevation angle especially affects the patterns of B:G and B:R ratios. Water vapour has a large effect on the R:FR photon ratio and modelled climate scenarios predict that increasing global temperatures will result in increased atmospheric water vapour. The development of proxy models, utilising available data from weather and climate models, for relevant photon ratios as a function of solar elevation angle and atmospheric factors would facilitate the interpretation of results from past, present and future field studies of plants and vegetation.}, journal={AGRICULTURAL AND FOREST METEOROLOGY}, author={Kotilainen, T. and Aphalo, P. J. and Brelsford, C. C. and Book, H. and Devraj, S. and Heikkila, A. and Hernandez, R. and Kylling, A. and Lindfors, A. and Robson, T. M.}, year={2020}, month={Sep} }
 @article{xu_hernandez_2020, title={The Effect of Light Intensity on Vegetative Propagation Efficacy, Growth, and Morphology of "Albion" Strawberry Plants in a Precision Indoor Propagation System}, volume={10}, ISSN={["2076-3417"]}, url={http://dx.doi.org/10.3390/app10031044}, DOI={10.3390/app10031044}, abstractNote={Open-field strawberry propagation is faced with several challenges such as lack of daughter plants, low quality, and disease transmission. Propagating strawberry plants in a completely enclosed controlled environment using a precision indoor propagation (PIP) system could overcome some of the challenges seen in open-field strawberry propagation. Optimizing the light intensity in a PIP system improves plant growth and reduce propagation cost. In the present study, “Albion” strawberry plants were grown as stock plants in a PIP system to examine plant propagation efficacy under three light intensities, PPF-250 (241 ± 13), PPF-350 (337 ± 13), or PPF-450 (443 ± 17) photosynthetic photon flux density (PPFD, μmol m−2 s−1) at 12 h photoperiod. They were grown under 25.7 ± 0.05 °C temperature, 0.95 ± 0.04 kPa vapor pressure deficit, and 73% ± 5.2% relative humidity. The number of daughter plants, morphology, and growth were recorded weekly (non-destructive measurements) for two intervals (01 to 12 weeks and 12 to 21 weeks). The number, total dry mass, and total fresh mass of daughter plants per stock plant increased with the increase in light intensity. The propagation efficacy to light ranged between 0.3 and 1.9 daughter plants per mole of light, depending on light intensity and harvest time. The number of daughter plants per week was estimated to be 36.2 plants wk−1 m−2. Daughter plants were classified by size and size was not influenced by the light treatment. Stock plant crown diameter, leaf area, fresh mass, dry mass, and leaf count all increased with an increase in PPFD. The shoot dry mass percent distribution to the daughter plant was 45% to 46% and was not affected by light intensity treatment. This study demonstrates the feasibility of using PIP systems for the production of strawberry daughter plants.}, number={3}, journal={APPLIED SCIENCES-BASEL}, author={Xu, Xiangnan and Hernandez, Ricardo}, year={2020}, month={Feb} }
 @article{gomez_currey_dickson_kim_hernandez_sabeh_raudales_brumfield_laury-shaw_wilke_et al._2019, title={Controlled Environment Food Production for Urban Agriculture}, volume={54}, ISBN={2327-9834}, DOI={10.21273/HORTSCI14073-19}, abstractNote={The recent increased market demand for locally grown produce is generating interest in the application of techniques developed for controlled environment agriculture (CEA) to urban agriculture (UA). Controlled environments have great potential to revolutionize urban food systems, as they offer unique opportunities for year-round production, optimizing resource-use efficiency, and for helping to overcome significant challenges associated with the high costs of production in urban settings. For urban growers to benefit from CEA, results from studies evaluating the application of controlled environments for commercial food production should be considered. This review includes a discussion of current and potential applications of CEA for UA, references discussing appropriate methods for selecting and controlling the physical plant production environment, resource management strategies, considerations to improve economic viability, opportunities to address food safety concerns, and the potential social benefits from applying CEA techniques to UA. Author’s viewpoints about the future of CEA for urban food production are presented at the end of this review.}, number={9}, journal={HORTSCIENCE}, author={Gomez, Celina and Currey, Christopher J. and Dickson, Ryan W. and Kim, Hye-Ji and Hernandez, Ricardo and Sabeh, Nadia C. and Raudales, Rosa E. and Brumfield, Robin G. and Laury-Shaw, Angela and Wilke, Adam and et al.}, year={2019}, month={Sep}, pages={1448–1458} }
 @article{lam_choi_kim_park_hernandez_2019, title={Optimizing Plant Spacing and Harvest Time for Yield and Glucosinolate Accumulation in Watercress (Nasturtium officinale L.) Grown in a Hydroponic System}, volume={37}, ISSN={["2465-8588"]}, DOI={10.7235/HORT.20190073}, abstractNote={The objective of the present study was to evaluate the effects of plant spacing (14-, 20-, and 31-cm) on the lateral branch length, shoot fresh and dry weights, yield, and glucosinolate content of watercress at 35 and 56 days after transplanting (DAT) in a hydroponic culture system. Two-week-old seedlings were transplanted into three deep flow technique systems in a greenhouse with three plant spacing treatments: 31-cm (36 plants per bed), 20-cm (72 plants per bed), and 14-cm (144 plants per bed). Each treatment had three beds and the size of each bed was 3.24 m 2 . The lateral branch length, shoot fresh and dry weights, and yield were measured, and glucosinolate concentration in leaves and stems of watercress was analyzed at 35 and 56 DAT. Both lateral branch length and yield per unit area were significantly reduced by increasing plant spacing, whereas the shoot fresh and dry weights were significantly increased. The total concentration of glucosinolate in the shoots was higher at 56 DAT than at 35 DAT. Furthermore, at 35 DAT, the glucosinolate concentration was the highest in the leaves and stems of plants grown under 14-cm and 31-cm spacing, respectively, than under other spacing treatments. However, at 56 DAT, the total glucosinolate concentration was higher in the leaves and stems of plants grown under 20and 31-cm spacing and under 14and 20-cm spacing, respectively. The highest total glucosinolate content per shoot in a unit area was observed under 14-cm spacing at 35 DAT (6.58 mmol/shoot DW/m 2 ) and under 20-cm spacing at 56 DAT (51.99 mmol/shoot DW/m 2 ). These results suggest that watercress yield could be optimized by growing plants under 14-cm spacing and harvesting at 35 DAT, whereas growing plants under 20-cm spacing and harvesting at 56 DAT would be an optimal method for increasing glucosinolate content without negatively affecting the growth of plants grown under a hydroponic culture system in a greenhouse. Additional key words: days after transplanting, deep flow technique, greenhouse, shoot fresh and dry weight, unit area}, number={6}, journal={HORTICULTURAL SCIENCE & TECHNOLOGY}, author={Lam, Vu Phong and Choi, Jaeyun and Kim, Sungjin and Park, Jongseok and Hernandez, Ricardo}, year={2019}, pages={733–743} }
 @article{light quality characterization under climate screens and shade nets for controlled-environment agriculture_2018, url={http://dx.doi.org/10.1371/journal.pone.0199628}, DOI={10.1371/journal.pone.0199628}, abstractNote={Climate screens are typically used inside glass greenhouses to improve control of humidity and temperature, and thus reduce energy expenditure. Shade nets are more appropriate to use, either with or without polyethylene cladding, at locations less-reliant on climate control, but where protection against hail, wind and excessive solar radiation might be needed. In addition, insect screens and nets can be employed to hinder insect pests and other invertebrates entering either type of production environment, and to keep invertebrates used in pest management contained inside. Screens and nets both transmit sunlight in a wavelength-specific manner, giving them the potential to affect plant morphology and physiology. Screens and nets of various colours and nominal shading factors have been described and studied; however, detailed measurements of their spectral characteristics are scarce. We measured solar spectral photon-irradiance and its attenuation by climate screens, shade nets, insect nets, greenhouse glass, and polyethylene covers. Our aim was to elucidate the effects of different patterns, colours, and shading factors, on light quality in production environments. Our measurements reveal that there are large differences both in the fraction of global irradiance attenuated and spectral ratios received under materials that are otherwise superficially similar in terms of their appearance and texture. We suggest that the type of spectral characterization that we performed is required to fully interpret the results of research examining plant responses to different types of screen and net. These data on spectral irradiance would benefit material manufacturers, researchers, growers, and horticultural consultants, enabling material selection to better match the solutions sought by growers and their desired outcomes regarding plant performance.}, journal={PLOS ONE}, year={2018}, month={Jun} }
 @article{morphology and growth of ornamental seedlings grown under supplemental light-emitting diode lighting and chemical plant-growth regulators_2018, url={http://dx.doi.org/10.17660/actahortic.2018.1227.65}, DOI={10.17660/actahortic.2018.1227.65}, journal={Acta Horticulturae}, year={2018}, month={Nov} }
 @article{transplant lettuce response to different blue:red photon flux ratios in indoor led sole-source lighting production_2018, url={http://dx.doi.org/10.17660/actahortic.2018.1227.70}, DOI={10.17660/actahortic.2018.1227.70}, journal={Acta Horticulturae}, year={2018}, month={Nov} }
 @inbook{light quality and photomorphogenesis_2017, booktitle={Light management in controlled environments}, year={2017} }
 @article{eguchi_hernandez_kubota_2016, title={End-of-day far-red lighting combined with blue-rich light environment to mitigate intumescence injury of two interspecific tomato rootstocks}, volume={1134}, ISSN={["2406-6168"]}, DOI={10.17660/actahortic.2016.1134.22}, abstractNote={Effects of end-of-day far-red (EOD-FR, 700-800 nm) light and high blue photon flux ratio during the photoperiod on intumescence injury were examined for 'Beaufort' and 'Maxifort' tomato rootstock seedlings (Solanum lycopersicum × Solanum habrochaites) grown with 13 mol m-2 d-1 daily light integral (199 µmol m-2 s-1 photosynthetic photon flux, 18 h photoperiod). The EOD-FR light treatment (1.1 mmol m-2 d-1 provided by 6.0 µmol m-2 s-1 FR photon flux for 3 min at EOD) significantly reduced intumescence injury. For example, by the EOD-FR light treatment, the incidences of leaf abscission were reduced from 88 to 8% for 'Beaufort' and from 79 to 25% for 'Maxifort'. However, EOD-FR light caused undesirable stem extension (41% greater than that without EOD-FR light). By combining relatively high B (blue, 400-500 nm) to R (red, 600-700 nm) photon flux ratio (50%B-50%R) during the photoperiod with EOD-FR light, intumescence injury was further decreased without causing undesirable stem extension. For example, the incidences of leaf abscission were reduced from 88 to 0% for 'Beaufort' and from 79 to 0% for 'Maxifort', compared to those under 10%B-90%R without EOD-FR light. Also, the percentages of leaves that exhibited intumescences were reduced from 68 to 30% for 'Beaufort' and from 55 to 19% for 'Maxifort'. Our study demonstrated that blue-rich light quality combined with a small dose of EOD-FR lighting could be applied to mitigate the problematic intumescence injury of tomato seedlings grown under LEDs.}, journal={VIII INTERNATIONAL SYMPOSIUM ON LIGHT IN HORTICULTURE}, author={Eguchi, T. and Hernandez, R. and Kubota, C.}, year={2016}, pages={163–170} }
 @article{eguchi_hernandez_kubota_2016, title={Far-red and Blue Light Synergistically Mitigate Intumescence Injury of Tomato Plants Grown Under Ultraviolet-deficit Light Environment}, volume={51}, ISSN={["2327-9834"]}, url={http://dx.doi.org/10.21273/hortsci.51.6.712}, DOI={10.21273/hortsci.51.6.712}, abstractNote={Intumescence injury is an abiotic-stress-induced physiological disorder associated with abnormal cell enlargement and cell division. The symptom includes blister- or callus-like growths on leaves, which occur on sensitive cultivars of tomato when they are grown under ultraviolet (UV)-deficit light environment, such as light-emitting diodes (LEDs). Previous studies suggest that intumescence can be reduced by increasing far-red (FR) or blue light. In the present study, effects of end-of-day FR (EOD-FR) light and high blue photon flux (PF) ratio during the photoperiod on intumescence injury were examined using ‘Beaufort’ interspecific tomato rootstock seedlings ( Solanum lycopersicum × Solanum habrochaites ), a cultivar highly susceptible to intumescence injury. Our study showed that EOD-FR light treatment moderately suppressed intumescence injury. Using EOD-FR light treatment, the percent number of leaves exhibiting intumescences was reduced from 62.0–70.7% to 39.4–43.1%. By combining high blue PF ratio (75%) during the photoperiod and EOD-FR light treatment, the percent number of leaves exhibiting intumescences was further suppressed to 5.0%. Furthermore, the combination of high blue PF ratio and EOD-FR light treatment inhibited undesirable stem elongation caused by EOD-FR light treatment. We found that high blue PF ratio during the photoperiod combined with a small dose of EOD-FR lighting (≈1 mmol·m −2 ·d −1 provided by 5.2 µmol·m −2 ·s −1 FR PF for 3.3 minutes) could inhibit the problematic intumescence injury of tomato plants grown under LEDs without negatively influencing growth or morphology.}, number={6}, journal={HORTSCIENCE}, author={Eguchi, Tomomi and Hernandez, Ricardo and Kubota, Chieri}, year={2016}, month={Jun}, pages={712–719} }
 @article{hernandez_eguchi_kubota_2016, title={Growth and morphology of vegetable seedlings under different blue and red photon flux ratios using light-emitting diodes as sole-source lighting}, volume={1134}, ISSN={["2406-6168"]}, DOI={10.17660/actahortic.2016.1134.26}, journal={VIII INTERNATIONAL SYMPOSIUM ON LIGHT IN HORTICULTURE}, author={Hernandez, R. and Eguchi, T. and Kubota, C.}, year={2016}, pages={195–200} }
 @article{hernández_kubota_2016, title={Physiological responses of cucumber seedlings under different blue and red photon flux ratios using LEDs}, volume={121}, ISSN={0098-8472}, url={http://dx.doi.org/10.1016/j.envexpbot.2015.04.001}, DOI={10.1016/j.envexpbot.2015.04.001}, abstractNote={Light emitting diodes (LEDs) are frequently regarded as a new light source for the production of horticultural crops under closed-type conditions. However, before use of LEDs as the sole source of light can be advanced, plant responses to light quality have to be investigated for important horticultural plants. The objective of the present study was to evaluate cucumber (Cucumis sativus) seedlings physiological responses to different blue (B) and red (R) photon flux (PF) ratios using LEDs. Cucumber seedlings (cv. Cumlaude) were grown in a growth chamber until the second true leaf stage (17 days) with LED lighting and 18-h photoperiod. The treatments consisted of 100 μmol m−2 s−1 photosynthetic photon flux (PPF) with B:R PF ratios of 0B:100R%, 10B:90R%, 30B:70R%, 50B:50R%, 75B:25R%, 100B:0R%. Another treatment consisted of B, green (G) and R PF ratio of 20B:28G:52R%. Peak wavelengths of LEDs were 455 nm (B) and 661 nm (R) for the in the B:R treatments and 473 nm (B), 532 nm (G), 660 nm (R) in the B:G:R treatment. Hypocotyl length decreased with the increase of B PF up to the 75B:25R% treatment. Hypocotyl length in the 0B:100R% treatment was 164% greater than in the 75B:25R treatment. Plants under the 100B:0R% treatment had unexpected greater plant height, hypocotyl, and epicotyl length than plants under all other treatments. For example, the hypocotyl length under the 100B:0R% was 69% greater than in the 0B:100R treatment and 346% greater than in the 75B:25R% treatment. Leaf area decreased with the increase of B PF when plants were irradiated with the combination of B and R PF. The response of leaf area under the 100B:0R% treatment was unexpected since plants in the 100B:0R% treatment had 48% greater leaf area than plants in the 75B:25R% treatment. Chlorophyll content per leaf area, net photosynthetic rate, and stomatal conductance increased with the increase of B PF. Shoot dry and fresh mass decreased with the increase of B PF when plants were irradiated with the combination of B and R PF. Plants under 0B:100R% had the lowest dry and fresh mass from all the treatments and plants under 100B:0R% showed the greatest fresh mass from all the treatments and equal dry mass as the plants under 10B:90R% treatment. The addition of G PF to the spectrum did not have any influence in cucumber plant responses. For cucumber seedlings, morphological responses influenced plant growth since B PF responses in growth parameters (i.e., dry mass) closely matched those in morphological parameter (i.e., leaf area). More research is needed to find the optimal spectrum for the growth and development of horticultural crops under sole source electrical lighting such as LEDs.}, journal={Environmental and Experimental Botany}, publisher={Elsevier BV}, author={Hernández, R. and Kubota, C.}, year={2016}, month={Jan}, pages={66–74} }
 @article{hernandez_eguchi_deveci_kubota_2016, title={Tomato seedling physiological responses under different percentages of blue and red photon flux ratios using LEDs and cool white fluorescent lamps}, volume={213}, ISSN={["1879-1018"]}, url={http://dx.doi.org/10.1016/j.scienta.2016.11.005}, DOI={10.1016/j.scienta.2016.11.005}, abstractNote={Lamp spectral customization can be a strategy to achieve desirable plant characteristics when plants are grown under sole-source electric lighting. Vegetable transplants can be efficiently and economically grown under indoor-production systems with electrical lighting; however, species-specific light recipes have to be developed to improve plant growth, development and morphology, as well as to reduce electrical consumption. The objective of this study was to evaluate the growth and morphology of tomato transplants to a broad range of blue to red (B:R) photon flux (PF) ratios under LEDs and cool white fluorescent lamps (CWF). Tomato ‘Komeett’ and ‘Beaufort’ seedlings were grown in a climate control growth chamber. Using LEDs, seven light treatments with different blue (B), green (G) and red (R) PF ratios were used: 100R, 10B:90R, 20B:28G:52R, 30B:70R, 50B:50R, 75B:25R and 100B. In addition, a CWF treatment served as the control. Hypocotyl length of ‘Komeett’ decreased with the increase of percent B PF up to 75% B. Plant leaf area was 64–72% greater under treatments emitting both B and R PF than in the 100 B and 100 R treatments. Similarly, tomato ‘Komeett’ fresh mass, dry mass, leaf number and chlorophyll concentration was comparable among the treatments containing B and R PF and greater than in 100 B and 100 R treatments. However, plant compactness in the 30B:70R treatment was 42% greater than in the 10B:90R treatment. Anthocyanin concentration increased with the increase of percent B PF up to 75% B. Also, plants in 30B:70R and 50B:50R had 39% and 36% greater dry mass than in CWF, respectively. In addition, 30B:70R and 50B:50R LEDs had 172% greater growing efficacy (g k Wh−1) than high output fluorescent lamps. The addition of G light did not have any effects on tomato physiological responses. ‘Beaufort’ plant morphology and growth were severely affected by intumescences development and intumescence severity decreased under higher percentages of B PF. In summary, 30B:70R, 50B:50R were the best spectrums to produce tomato seedlings under LEDs tested here; however, plant quality under CWF, 10B:90R, 20B:28G:52R, and 75B:25R was also acceptable.}, journal={SCIENTIA HORTICULTURAE}, author={Hernandez, Ricardo and Eguchi, Tomomi and Deveci, Murat and Kubota, Chieri}, year={2016}, month={Dec}, pages={270–280} }
 @inbook{light-emitting diodes in horticulture_2015, url={http://dx.doi.org/10.1002/9781119107781.ch01}, DOI={10.1002/9781119107781.ch01}, abstractNote={Chapter 1 Light-Emitting Diodes in Horticulture Cary A. Mitchell, Cary A. Mitchell Department of Horticulture & Landscape Architecture, Purdue University, West Lafayette, IN USASearch for more papers by this authorMichael P. Dzakovich, Michael P. Dzakovich Department of Horticulture & Landscape Architecture, Purdue University, West Lafayette, IN USASearch for more papers by this authorCelina Gomez, Celina Gomez Department of Horticulture & Landscape Architecture, Purdue University, West Lafayette, IN USASearch for more papers by this authorRoberto Lopez, Roberto Lopez Department of Horticulture & Landscape Architecture, Purdue University, West Lafayette, IN USASearch for more papers by this authorJohn F. Burr, John F. Burr Krannert School of Business Management, Purdue University, West Lafayette, IN USASearch for more papers by this authorRichardo Hernández, Richardo Hernández School of Plant Sciences, The University of Arizona, Tucson, AZ USASearch for more papers by this authorChieri Kubota, Chieri Kubota School of Plant Sciences, The University of Arizona, Tucson, AZ USASearch for more papers by this authorChristopher J. Currey, Christopher J. Currey Department of Horticulture, Iowa State University, Ames, IA USASearch for more papers by this authorQingwu Meng, Qingwu Meng Department of Horticulture, Michigan State University, East Lansing, MI USASearch for more papers by this authorErik S. Runkle, Erik S. Runkle Department of Horticulture, Michigan State University, East Lansing, MI USASearch for more papers by this authorChristopher M. Bourget, Christopher M. Bourget Orbital Technologies Corporation, Madison, WI USASearch for more papers by this authorRobert C. Morrow, Robert C. Morrow Orbital Technologies Corporation, Madison, WI USASearch for more papers by this authorArend J. Both, Arend J. Both Department of Environmental Sciences, Rutgers University, New Brunswick, NJ USASearch for more papers by this author Cary A. Mitchell, Cary A. Mitchell Department of Horticulture & Landscape Architecture, Purdue University, West Lafayette, IN USASearch for more papers by this authorMichael P. Dzakovich, Michael P. Dzakovich Department of Horticulture & Landscape Architecture, Purdue University, West Lafayette, IN USASearch for more papers by this authorCelina Gomez, Celina Gomez Department of Horticulture & Landscape Architecture, Purdue University, West Lafayette, IN USASearch for more papers by this authorRoberto Lopez, Roberto Lopez Department of Horticulture & Landscape Architecture, Purdue University, West Lafayette, IN USASearch for more papers by this authorJohn F. Burr, John F. Burr Krannert School of Business Management, Purdue University, West Lafayette, IN USASearch for more papers by this authorRichardo Hernández, Richardo Hernández School of Plant Sciences, The University of Arizona, Tucson, AZ USASearch for more papers by this authorChieri Kubota, Chieri Kubota School of Plant Sciences, The University of Arizona, Tucson, AZ USASearch for more papers by this authorChristopher J. Currey, Christopher J. Currey Department of Horticulture, Iowa State University, Ames, IA USASearch for more papers by this authorQingwu Meng, Qingwu Meng Department of Horticulture, Michigan State University, East Lansing, MI USASearch for more papers by this authorErik S. Runkle, Erik S. Runkle Department of Horticulture, Michigan State University, East Lansing, MI USASearch for more papers by this authorChristopher M. Bourget, Christopher M. Bourget Orbital Technologies Corporation, Madison, WI USASearch for more papers by this authorRobert C. Morrow, Robert C. Morrow Orbital Technologies Corporation, Madison, WI USASearch for more papers by this authorArend J. Both, Arend J. Both Department of Environmental Sciences, Rutgers University, New Brunswick, NJ USASearch for more papers by this author Book Editor(s):Jules Janick, Jules Janick Purdue UniversitySearch for more papers by this author First published: 11 September 2015 https://doi.org/10.1002/9781119107781.ch01Citations: 35 AboutPDFPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShareShare a linkShare onEmailFacebookTwitterLinkedInRedditWechat Summary Light-emitting diodes (LEDs) have great potential to revolutionize lighting technology for the commercial horticulture industry. Unique LED properties of selectable, narrow-spectrum emissions, long life spans, cool photon-emitting surfaces, and rapidly improving energy use efficiency encourage novel lighting architectures and applications with promising profitability potential. In greenhouses, such unique properties can be leveraged for precise control of flowering and product quality for the floriculture industry, for energy-efficient propagation of ornamental and vegetable transplants, and for supplemental lighting of high-wire greenhouse vegetable crops for all-year production. In a sole-source lighting mode, LEDs can also be used for transplant production, as well as for production of rapid-turning vegetable and small fruit crops. Evidence is accumulating that nutritional and health attributes of horticultural products may be enhanced by specific wavelength combinations of narrow-spectrum light from LEDs. During periods of seasonally limited solar light, LEDs have potential to enhance daily light integral in greenhouses by providing supplemental photosynthetic radiation, particularly of red and blue light. The cool photon-emitting surfaces of LEDs permit their novel placement relative to crop foliar canopies, including close-canopy overhead lighting as well as within-canopy lighting, which greatly reduces electrical energy requirements while maintaining adequate incident photon fluxes. Because of the small size of individual LEDs and narrow beam angles from LED arrays, light distribution can be highly targeted and waste of light from LEDs minimized compared with other light sources traditionally used for horticulture. Prescriptions of spectral blends (e.g., red:far-red and red:blue ratios) can be developed for LEDs to accomplish specific photomorphogenic goals for seedling development, flowering, and possibly yield and produce quality. LED light quality may also be useful to control pest insects and to avoid physiological disorders otherwise caused by low-intensity or narrow-spectrum lighting. 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Growth responses of marigold and salvia bedding plants as affected by monochromic or mixture radiation provided by a light-emitting diode (LED). Plant Growth Regul. 38: 225–230. 10.1023/A:1021523832488 CASWeb of Science®Google Scholar Hernández, R., and Kubota, C. 2012. Tomato seedling growth and morphological responses to supplemental LED lighting red:blue ratios under varied daily light integrals. Acta Hort. 956: 187–194. 10.17660/ActaHortic.2012.956.19 Web of Science®Google Scholar Hernández, R., and C. Kubota. 2014a. Growth and morphological response of cucumber seedlings to supplemental red and blue photon flux ratios under varied solar daily light integrals. Sci. Hort. 173C: 92–99. 10.1016/j.scienta.2014.04.035 Web of Science®Google Scholar Hernández, R., and C. Kubota. 2014b. LEDs supplemental lighting for vegetable transplant production: spectral evaluation and comparisons with HID technology. 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Environ. Bioinform. 9: 265–277. Google Scholar Hogewoning, S.W. 2010. On the photosynthetic and developmental responses of leaves to the spectral composition of light. Ph.D. diss., Wageningen University, the Netherlands. Google Scholar Hogewoning, S.W., G. Trouwborst, G.J. Engbers, J. Harbinson, W. van Ieperen, J. Ruijsch, A.H.C.M. Schapendonk, S.C. Pot, and O. van Kooten. 2007. Plant physiological acclimation to irradiation by light emitting diodes (LEDs). Acta Hort. 761: 183–191. 10.17660/ActaHortic.2007.761.23 CASGoogle Scholar Hogewoning, S.W., G. Trouwborst, H. Maljaars, H. Poorter, W. van leperen, and J. Harbinson. 2010. Blue light dose-responses of leaf photosynthesis, morphology, and chemical composition of Cucumis sativus grown under different combination}, booktitle={Horticultural Reviews: Volume 43}, year={2015}, month={Oct} }
 @article{hernández_kubota_2015, title={Physiological, Morphological, and Energy-use Efficiency Comparisons of LED and HPS Supplemental Lighting for Cucumber Transplant Production}, volume={50}, ISSN={0018-5345 2327-9834}, url={http://dx.doi.org/10.21273/hortsci.50.3.351}, DOI={10.21273/hortsci.50.3.351}, abstractNote={To increase the available photosynthetic photon flux (PPF) for plant growth, greenhouse growers sometimes use electric lighting to supplement solar light. The conventional lighting technology used to increase PPF in the greenhouse is high-pressure sodium lamps (HPS). A potential alternative to HPS is high-intensity light-emitting diodes (LEDs). The objective of this study is to compare supplemental LED lighting with supplemental HPS lighting in terms of plant growth and morphology as well as discuss the energy use efficiencies of the fixtures. There were three light treatments: 1) blue LED (peak wavelength 443 nm); 2) red LED (peak wavelength 633 nm); and 3) HPS, to provide 3.7 ± 0.2 mol·m·d (background solar radiation of 6.3 ± 0.9 mol·m·d). Cucumber (Cucumis sativus) plants at the transplanting stage (26 to 37 days) under HPS had 28% greater dry mass than did plants under the LED treatments. This can be attributed to the higher leaf temperature under the HPS treatment. No differences were observed in growth parameters (dry mass, fresh weight, or number of leaves) between the blue and red LED treatments. Plants under the blue LED treatment had greater net photosynthetic rate and stomatal conductance (gS) than those under the red LED and HPS treatments. Plants under the blue LED and HPS treatments had 46% and 61% greater hypocotyl length than those under the red LED, respectively. The fixture PPF efficiencies used in the experiment were 1.9, 1.7, and 1.64 mmol·J for the blue LED, red LED, and HPS treatments, respectively; however, the fixture growing efficiency (g·kWh) of HPS was 6% and 17% greater than the blue LED and red LED treatment, respectively. In summary, supplemental red LED produced desirable plant compactness and HPS had greater fixture growing efficiency than LEDs. Light is one of the limiting factors for plant growth. To increase the PPF for plant growth, greenhouse growers must supplement solar light with electric-powered light. The most common lighting technology used to increase PPF in the greenhouse is HPS. HPS are well accepted as a result of their relatively high fixture PPF efficiency. For example, single-ended and double-ended magnetic and electronic HPS PPF efficiencies range between 0.93 to 1.85 mmol·J (Nelson and Bugbee, 2013, 2014; Philips-Electronics, 2012). An alternative to HPS is the high-intensity LEDs, which currently have reportedly a PPF efficiency ranging between 0.84 and 2.3 mmol·J (Nelson and Bugbee, 2013, 2014; Philips, 2014) and are projected to have a 20-fold increase on their flux per lamp output over the next decade (Haitz and Tsao, 2011). In addition to their higher efficiencies, LED fixtures can also be built with a customized spectrum. By using different color diodes, growers have the opportunity to optimize spectra for specific growing purposes. In research using LEDs as the sole source light, plants such as peppers, wheat, lettuce, potato plantlets, Arabidopsis thaliana, soybeans, spinach, and radish grown under red light (600 to 700 nm) supplemented with blue light (400 to 500 nm) had greater growth rate and better plant development than plants grown under red light alone (Brown et al., 1995; Goins et al., 1997; Kim et al., 2005; Massa et al., 2008). Among limited information, recent studies testing LEDs as supplemental lighting have shown that the optimal electrical light spectrum for plant growth is different under sole-source lighting than for supplemental lighting For example, Hernández and Kubota (2014a, 2014b) found that plant responses to red and blue photon flux (PF) ratios of LED supplemental lighting were species-specific and dependent on background solar daily light integral (DLI). They concluded that monochromatic red supplemental lighting was preferred for the production of vegetable transplants because cucumber growth rate decreased with the increased of blue PF under low solar DLI (5.2 ± 1.2 mol·m·d) (Hernández and Kubota, 2014a). To advance the use of LEDs as a supplemental lighting technology in greenhouses, they have to be compared with the current HPS technology in terms of plant responses and energy consumption. Limited information is available comparing HPS supplemental lighting with LED supplemental lighting in terms of plant growth and development. Currey and Lopez (2013) showed greater leaf and root dry mass on Petunia cuttings grown under LED supplemental lighting with 70:30 red:blue PF ratios compared with the cuttings grown under HPS supplemental lighting. Bergstrand and Schussler (2013) showed that Chrysanthemum plant biomass production was greater under HPS supplemental lighting than those under supplemental red:blue and white LED supplemental lighting. Limited and conflicting research reports are available comparing energy consumption between LED and HPS supplemental lighting. For example, for fresh head lettuce, Martineau et al. (2012) showed greater lettuce dry mass per electric energy input in plants grown under LED supplemental lighting than those under supplemental HPS lighting and reported a 33.8% greater electricity consumption by the HPS supplemental lighting. In tomato, Gomez et al. (2013) showed no increase in yield under supplemental LED lighting compared with the yield under supplemental HPS lighting, but reported 76% greater electrical consumption by the HPS supplemental lighting treatment compared with the LED supplemental lighting treatment. Pinho et al. (2012) reported that a small-scale experiment of supplemental lighting (1-m plant growing area) consumed a 40% greater electricity by the HPS lighting than the LED lighting to achieve the same PPF over the canopy. However, when simulated for a commercial greenhouse with 800 m, HPS lighting was shown to be 44% energy-saving than LED lighting (Pinho et al., 2012). Plant growth rate per fixture’s electric power consumption is highly correlated to the fixture’s PPF electrical efficiency (mmol·s·W or mmol·J). More PPF per watt (W) often translates to greater growth rate per kWh. If a LED fixture produces greater growth rate than a HPS fixture and both have similar PPF efficiency (LED: 0.84 to 2.3 mmol·J, HPS: 0.93 to 1.85 mmol·J), two explanations are possible: 1) plant growth rate is much more enhanced by spectral optimization under the LEDs; and 2) the experimental design causes a disproportionate amount of supplemental PPF of the HPS fixture to fall outside the growing area as a result of a higher fixture density and consequently higher energy consumption than supplemental LED fixtures. In the latter case, interpretation of energy consumption should be carefully done because it presents misleading information and is biased toward LEDs. To our knowledge, no literature is available on the comparison of HPS to LED supplemental lighting for the production of Received for publication 2 Oct. 2014. Accepted for publication 11 Dec. 2014. This project was funded by USDA NIFA SCRI grant No. 2010-51181-21369. We thank Mark Kroggel and Neal Barto at the University of Arizona (CEAC) for their technical advice and Jose Pablo Santana for his help during the experiment. To whom reprint requests should be addressed; e-mail ricahdez@email.arizona.edu. HORTSCIENCE VOL. 50(3) MARCH 2015 351 CROP PRODUCTION}, number={3}, journal={HortScience}, publisher={American Society for Horticultural Science}, author={Hernández, Ricardo and Kubota, Chieri}, year={2015}, month={Mar}, pages={351–357} }
 @article{hernández_kubota_2014, title={Growth and morphological response of cucumber seedlings to supplemental red and blue photon flux ratios under varied solar daily light integrals}, volume={173}, ISSN={0304-4238}, url={http://dx.doi.org/10.1016/j.scienta.2014.04.035}, DOI={10.1016/j.scienta.2014.04.035}, abstractNote={High intensity light-emitting diodes (LEDs) have the potential to be used as supplemental lighting technology in greenhouses. However, LED light quality requirements of greenhouse crops grown when supplementing the solar spectrum are unknown. In this study, to find the requirements, cucumber (Cucumis sativus L. cv. Cumlaude) seedlings were grown in a greenhouse with and without supplemental LED lighting (PPF: 54 ± 1.1 μmol m−2 s−1) at varied blue (400–500 nm with the peak at 455 nm) and red (600–700 nm with the peak at 661 nm) photon flux (PF) ratios (B:R ratios) under different solar daily light integrals (DLI). The treatments were 0B:100R% (54 μmol m−2 s−1 red PF), 4B:96R% (2.3 and 52 μmol m−2 s−1 blue and red PF, respectively), 16B:84R% (8.5 and 46.2 μmol m−2 s−1 blue and red PF, respectively), and a control without supplemental lighting. The solar DLIs during the experiment were 5.2 ± 1.2 and 16.2 ± 5.3 mol m−2 d−1 created inside a greenhouse using shade screen. Regardless of B:R ratio, morphological and growth parameters of the seedlings were all improved under supplemental LED lighting compared to the no-supplemental-light control. Under high DLI conditions, no significant differences were found for any parameters between the different B:R ratios. Under low DLI, chlorophyll concentration increased with increasing B:R ratio (i.e., increasing blue PF without increasing photosynthetic photon flux, PPF) of the supplemental lighting. Dry mass, leaf number, and leaf area decreased with increasing B:R ratio under low DLI conditions. The reduction in dry mass and leaf number were attributed to the reduction in leaf area. Leaf net photosynthetic rate measured under ambient CO2, ambient temperature, and 1000 μmol m−2 s−1 PPF (light source: tungsten halogen lamp) also showed no difference among treatments of B:R ratios, indicating that B:R ratio treatments did not cause any changes in plant photosynthetic apparatus. When used for supplemental lighting in the greenhouse, use of 100% red LED is preferred for cucumber seedlings, and additional blue LED was not beneficial.}, journal={Scientia Horticulturae}, publisher={Elsevier BV}, author={Hernández, Ricardo and Kubota, Chieri}, year={2014}, month={Jun}, pages={92–99} }
 @article{leds supplemental lighting for vegetable transplant production: spectral evaluation and comparisons with hid technology_2014, url={http://dx.doi.org/10.17660/actahortic.2014.1037.110}, DOI={10.17660/actahortic.2014.1037.110}, journal={Acta Horticulturae}, year={2014}, month={May} }
 @article{pulsing effects of supplemental led lighting on cucumber seedlings growth and morphology in greenhouse_2014, url={http://dx.doi.org/10.17660/actahortic.2014.1037.117}, DOI={10.17660/actahortic.2014.1037.117}, journal={Acta Horticulturae}, year={2014}, month={May} }
 @article{hernández_kubota_2012, title={Tomato seedling growth and morphological responses to supplemental led lighting red: blue ratios under varied daily solar light integrals.}, volume={956}, ISSN={0567-7572 2406-6168}, url={http://dx.doi.org/10.17660/actahortic.2012.956.19}, DOI={10.17660/actahortic.2012.956.19}, journal={Acta Horticulturae}, publisher={International Society for Horticultural Science (ISHS)}, author={Hernández, R. and Kubota, C.}, year={2012}, month={Oct}, pages={187–194} }
 @article{hernández_guo_harris_liu_2011, title={Effects of selected insecticides on adults of two parasitoid species of Liriomyza trifolii: Ganaspidium nigrimanus (Figitidae) and Neochrysocharis formosa (Eulophidae)}, volume={18}, ISSN={1672-9609}, url={http://dx.doi.org/10.1111/j.1744-7917.2010.01391.x}, DOI={10.1111/j.1744-7917.2010.01391.x}, abstractNote={Abstract  Liriomyza trifolii is an important pest of vegetables and ornamental crops around the world. This pest is attacked by many parasitoid species. The principal management tactic used against L. trifolii is insecticide application. Insecticides vary in their effects on parasitoid species and insecticides that have less harmful effects should be preferred for the control of this pest. In this study, novaluron, abamectin, λ‐cyhalothrin and spinetoram were investigated for their lethal effects on adults of Neochrysocharis formosa and Ganaspidium nigrimanus, two important parasitoids of L. trifolii. Three different bioassays were used on adult parasitoids: direct insecticide application, insecticide intake and insecticide residue. Adult parasitoid response to novaluron exhibited the least lethal effects among the bioassays and insecticides tested. Abamectin had significant mortality to both parasitoid species in the direct application and insecticide intake bioassays and mortality were high for G. nigrimanus in the residue bioassay. Spinetoram was the most harmful insecticide to the adult parasitoids in all three bioassays. λ‐cyhalothrin effects varied between the two parasitoids. In the direct application, it was harmful to G. nigrimanus and had no effect on N. formosa. In the insecticide intake bioassay λ‐cyhalothrin had no effect in survival of either species, and in the residue bioassay it reduced parasitoid survival of both species. Potential tolerance of N. formosa to λ‐cyhalothrin is discussed.}, number={5}, journal={Insect Science}, publisher={Wiley}, author={Hernández, Ricardo and Guo, Kun and Harris, Marvin and Liu, Tong-Xian}, year={2011}, month={Mar}, pages={512–520} }
 @inbook{hymenopteran parasitoids and their role in biological control of vegetable liriomyza leafminers_2011, url={http://dx.doi.org/10.1007/978-3-642-17815-3_22}, DOI={10.1007/978-3-642-17815-3_22}, booktitle={Recent Advances in Entomological Research}, year={2011} }
 @article{hernández_harris_liu_2011, title={Impact of Insecticides on Parasitoids of the Leafminer,Liriomyza trifolii,in Pepper in South Texas}, volume={11}, ISSN={1536-2442}, url={http://dx.doi.org/10.1673/031.011.6101}, DOI={10.1673/031.011.6101}, abstractNote={Abstract Liriomyza leafminers (Diptera: Agromyzidae) are cosmopolitan, polyphagous pests of horticultural plants and many are resistant to insecticides. Producers in South Texas rely on insecticides as the primary management tool for leafminers, and several compounds are available. The objective of this study is to address the efficacy of these compounds for controlling Liriomyza while minimizing their effects against natural enemies. Research plots were established at Texas AgriLife research center at Weslaco, Texas in fall 2007 and spring 2008 seasons, and peppers were used as a model crop. Plots were sprayed with novaluron, abamectin, spinetoram, lambda-cyhalothrin and water as treatments according to leafminer infestation; insecticide efficacy was monitored by collecting leaves and infested foliage. Plant phenology was also monitored. Novaluron was the most effective insecticide and lambda-cyhalothrin showed resurgence in leafminer density in fall 2007 and no reduction in spring 2008. Other compounds varied in efficacy. Novaluron showed the least number of parasitoids per leafminer larva and the lowest parasitoid diversity index among treatments followed by spinetoram. Liriomyza trifolii (Burgess) was the sole leafminer species on peppers, and 19 parasitoid species were found associated with this leafminer. Application of these insecticides for management of leafminers with conservation of natural enemies is discussed.}, number={61}, journal={Journal of Insect Science}, publisher={Oxford University Press (OUP)}, author={Hernández, Ricardo and Harris, Marvin and Liu, Tong-Xian}, year={2011}, month={May}, pages={1–14} }
 @inbook{liu_kang_lei_hernández_2010, title={Hymenopteran Parasitoids and Their Role in Biological Control of Vegetable Liriomyza Leafminers}, booktitle={Recent advances in entomological research}, publisher={Higher Education Press}, author={Liu, T.X. and Kang, L. and Lei, Z. and Hernández, R.}, year={2010}, pages={228–243} }
 @article{hernández_harris_crosby_liu_2010, title={Liriomyza(Diptera: Agromyzidae) and Parasitoid Species on Pepper in the Lower Rio Grande Valley of Texas}, volume={35}, ISSN={0147-1724 0147-1724}, url={http://dx.doi.org/10.3958/059.035.0104}, DOI={10.3958/059.035.0104}, abstractNote={Abstract. 
 Liriomyza (Diptera: Agromyzidae) leafminers are polyphagous and important pests of vegetables, field crops, and ornamental plants around the world. Liriomyza cause economic damage to vegetable crops in the Lower Rio Grande Valley of Texas. The current species composition of the leafminers and associated parasitoid species is unknown. Infested foliage and pupae collected from sand-filled trays beneath pepper, Capsicum annum L., plants were sampled in fields in the Lower Rio Grande Valley in fall 2007 and spring 2008. Foliage was stored in ziplocked bags to allow specimen emergence, and sand from the trays was sieved to collect pupae. All specimens that emerged as adults were identified and recorded. Liriomyza trifolii (Burgess) was the dominant species in peppers in the Lower Rio Grande Valley, accounting for 99% of the specimens identified. Our survey showed 20 species of parasitoids from four families (Eulophidae, Braconidae, Figitidae, and Pteromalidae) to be associated with L. trifolii. Neochrysacharis formosa (Westwood) was the most abundant parasitoid during both seasons, accounting for ≈60% of the specimens.}, number={1}, journal={Southwestern Entomologist}, publisher={Society of Southwestern Entomologists}, author={Hernández, Ricardo and Harris, Marvin and Crosby, Kevin and Liu, Tong-Xian}, year={2010}, month={Mar}, pages={33–43} }
 @article{comparative transcript profiling in roots of phaseolus acutifolius and p. vulgaris under water deficit stress_2007, url={http://dx.doi.org/10.1016/j.plantsci.2007.08.003}, DOI={10.1016/j.plantsci.2007.08.003}, abstractNote={Transcript profiles in roots of Phaseolus acutifolius and P. vulgaris were compared under water deficit conditions that demonstrated the drought resistance phenotype of P. acutifolius. Differential gene expression was monitored with microarray analysis using slides printed with ∼5200 anonymous cDNAs from libraries of Phaseolus spp. Those genes whose expression was significantly altered by water deficit were sequenced and functional classifications were inferred based on similarity to other annotated genes. Fewer genes (n = 64) were responsive in P. vulgaris, the more drought sensitive species, compared with P. acutifolius (n = 488). Only 25 genes were drought responsive in the roots of both species, at a drought stress level of −2.5 MPa leaf water potential. Most of the responsive genes in P. vulgaris were in the functional class for stress responsive genes, while the largest functional class in P. acutifolius was populated with unannotated or novel genes. There were a number of genes likely to be important in cell growth and metabolism that were uniquely stress responsive in P. acutifolius.}, journal={Plant Science}, year={2007}, month={Nov} }
 @article{micheletto_rodriguez-uribe_hernández_richins_curry_o'connell_2007, title={Comparative transcript profiling in roots of Phaseolus acutifolius and P. vulgaris under water deficit stress}, volume={179}, number={5}, journal={Plant Science}, author={Micheletto, S. and Rodriguez-Uribe, L. and Hernández, R. and Richins, D.R. and Curry, J. and O'Connell, M.A.}, year={2007} }
 @article{hernández_rodriguez_o'connell_2006, title={Transcripts in drought stressed tepary bean roots}, journal={GenBank dbEST}, author={Hernández, R. and Rodriguez, L. and O'Connell, M.A.}, year={2006} }