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Nature | https://www.nature.com/srep/ | Published 01 October 2019

Resource use efficiency of indoor lettuce (Lactuca sativa L.) cultivation as affected by red:blue ratio provided by LED lighting

Giuseppina Pennisi 1,2,3, Francesco Orsini 1, Sonia Blasioli 1, Antonio Cellini 1, Andrea Crepaldi 5, Ilaria Braschi 1, Francesco Spinelli 1, Silvana Nicola 2, Juan A. Fernandez 3,Cecilia Stanghellini 6, Giorgio Gianquinto 1 & Leo F . M. Marcelis 4

1 DISTAL – Department of Agricultural and Food Sciences, ALMA MATER STUDIORUM – Bologna University,Bologna, Italy.
2 DISAFA–VEGMAP, Department of Agricultural, Forest and Food Sciences, University of Turin,Turin, Italy.
3 Departamento de Ingeniería Agronómica, E.T.S. Ingeniería Agronómica, Universidad Politécnica deCartagena, Cartagena, Spain.
4 Horticulture & Product Physiology Group, Wageningen University, Wageningen, The Netherlands.
5 Flytech s.r.l., Belluno, Italy.
6 Wageningen UR Greenhouse Horticulture, Wageningen, The Netherlands.

LED lighting in indoor farming systems allows to modulate the spectrum to fit plant needs. Red (R) and blue (B) lights are often used, being highly active for photosynthesis. The effect of R and B spectral components on lettuce plant physiology and biochemistry and resource use efficiency were studied. Five red:blue (RB) ratios (0.5-1-2-3-4) supplied by LED and a fluorescent control (RB = 1) were tested in six experiments in controlled conditions (PPFD = 215 µmol m–2 s–1, daylength 16 h). LED lighting increased yield (1.6 folds) and energy use efficiency (2.8 folds) as compared with fluorescent lamps. Adoption of RB = 3 maximised yield (by 2 folds as compared with RB = 0.5), also increasing leaf chlorophyll and flavonoids concentrations and the uptake of nitrogen, phosphorus, potassium and magnesium. As the red portion of the spectrum increased, photosystem II quantum efficiency decreased but transpiration decreased more rapidly, resulting in increased water use efficiency up to RB = 3 (75g FW L–1 H2O). The transpiration decrease was accompanied by lower stomatal conductance, which was associated to lower stomatal density, despite an increased stomatal size. Both energy and land surface use efficiency were highest at RB ≥ 3. We hereby suggest a RB ratio of 3 for sustainable indoor lettuce cultivation.
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Sustainability | https://www.mdpi.com/journal/sustainability | Published 27 July 2019

Modelling Environmental Burdens of Indoor-Grown Vegetables and Herbs as Affected by Red and Blue LED Lighting

Giuseppina Pennisi 1,2,3,†, Esther Sanyé-Mengual 1,†, Francesco Orsini 1,*,†, Andrea Crepaldi 4, Silvana Nicola 2, Jesús Ochoa 3, Juan A. Fernandez 3 and Giorgio Gianquinto 1

1 Department of Agricultural and Food Sciences (Distal), Research Centre in Urban Environment for Agriculture and Biodiversity (ResCUE-AB), University of Bologna, Viale Fanin, 44, 40127 Bologna, Italy
2 Department of Agricultural, Forest and Food Sciences, DISAFA-VEGMAP, University of Turin, Largo Paolo Braccini, 2, 10097 Grugliasco, Italy
3 Department of Agricultural Engineering, Universidad Politécnica de Cartagena, Paseo Alfonso XIII 48, 30203 Cartagena, Spain
4 Flytech s.r.l., Via dell'Artigianato, 65, Zona artigianale Paludi, 32010 Belluno, Italy
* Author to whom correspondence should be addressed.
† These authors equally contributed to this publication.

Notwithstanding that indoor farming is claimed to reduce the environmental pressures of food systems, electricity needs are elevated and mainly associated with lighting. To date, however, no studies have quantified the environmental and economic profile of Light Emitting Diodes (LED) lighting in indoor farming systems. The goal of this study is to quantify the effect of varying the red (R) and blue (B) LED spectral components (RB ratios of 0.5, 1, 2, 3 and 4) on the eco-efficiency of indoor production of lettuce, chicory, rocket and sweet basil from a life cycle perspective. The functional unit of the assessment was 1 kg of harvested fresh plant edible product, and the International Reference Life Cycle Data System (ILCD) method was employed for impact assessment. Even though most of the materials of the LED lamp and electronic elements were imported from long distances (14,400 km), electricity consumption was the largest contributor to the environmental impacts (with the LED lamps being the main electricity consumers, approximately 70%), apart from the resources use indicator, where the materials of the lamps and the mineral nutrients were also relevant. RB0.5 was the most energy-efficient light treatment but had the lowest eco-efficiency scores due to the lower crop yields.
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Frontiers in Plant Science | www.frontiersin.org | Original Research Published 13 March 2019

Unraveling the Role of Red:Blue LED Lights on Resource Use Efficiency and Nutritional Properties of Indoor Grown Sweet Basil

Giuseppina Pennisi 1,2,3, Sonia Blasioli 1, Antonio Cellini 1, Lorenzo Maia 1, Andrea Crepaldi 4, Ilaria Braschi 1, Francesco Spinelli 1, Silvana Nicola 2, Juan A. Fernandez 3, Cecilia Stanghellini 5, Leo F. M. Marcelis 6, Francesco Orsini 1,6 and Giorgio Gianquinto 1

1 DISTAL – Department of Agricultural and Food Sciences and Technologies, Alma Mater Studiorum – Universitá di Bologna, Bologna, Italy
2 DISAFA–VEGMAP, Department of Agricultural, Forest and Food Sciences, University of Turin, Turin, Italy
3 Departamento de Producción Vegetal, Escuela Técnica Superior de Ingenier√≠a Agronómica, Universidad Politécnica de Cartagena, Cartagena, Spain
4 Flytech s.r.l., Belluno, Italy
5 Wageningen UR Greenhouse Horticulture, Wageningen, Netherlands
6 Horticulture and Product Physiology Group, Wageningen University & Research, Wageningen, Netherlands

Indoor plant cultivation can result in significantly improved resource use efficiency (surface, water, and nutrients) as compared to traditional growing systems, but illumination costs are still high. LEDs (light emitting diodes) are gaining attention for indoor cultivation because of their ability to provide light of different spectra. In the light spectrum, red and blue regions are often considered the major plants energy sources for photosynthetic CO2 assimilation. This study aims at identifying the role played by red:blue (R:B) ratio on the resource use efficiency of indoor basil cultivation, linking the physiological response to light to changes in yield and nutritional properties. Basil plants were cultivated in growth chambers under five LED light regimens characterized by different R:B ratios ranging from 0.5 to 4 (respectively, RB0.5, RB1, RB2, RB3, and RB4), using fluorescent lamps as control (CK1). A photosynthetic photon flux density of 215 µmol m–2 s–1 was provided for 16 h per day. The greatest biomass production was associated with LED lighting as compared with fluorescent lamp. Despite a reduction in both stomatal conductance and PSII quantum efficiency, adoption of RB3 resulted in higher yield and chlorophyll content, leading to improved use efficiency for water and energy. Antioxidant activity followed a spectral-response function, with optimum associated with RB3. A low RB ratio (0.5) reduced the relative content of several volatiles, as compared to CK1 and RB ≥ 2. Moreover, mineral leaf concentration (g g–1 DW) and total content in plant (g plant–1) were influences by light quality, resulting in greater N, P, K, Ca, Mg, and Fe accumulation in plants cultivated with RB3. Contrarily, nutrient use efficiency was increased in RB ≤ 1. From this study it can be concluded that a RB ratio of 3 provides optimal growing conditions for indoor cultivation of basil, fostering improved performances in terms of growth, physiological and metabolic functions, and resources use efficiency.
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