Sustainable Greenhouse Production Research Articles

Life cycle assessment of a high-tech vertical decoupled aquaponic system for sustainable greenhouse production

IntroductionAquaponics provide multiple benefits due to the simultaneous yield of vegetables and fish, however they are characterized by increased greenhouse gas emissions owing to intensive production system. The most appropriate method for quantifying the environmental effects of these systems is Life Cycle Assessment with which the identification of hotspots and the suggestion of improved production plans can be achieved. The purpose of the present study was to evaluate the environmental impact of a pilot high-tech aquaponic system utilized for the simultaneous production of baby lettuce and rocket as well as rainbow trout, in indicators such as Global Warming Potential.Materials and methodsTo achieve this goal, data on inputs and outputs were collected from 12 case studies that were implemented, combining different fertilizer treatments, substrate choices, plant species cultivated and water source provision. Life Cycle Assessment was performed using SimaPro v.9.4.0.2 software.ResultsThe results showcase that the optimal case studies include the cultivation of baby lettuce and rocket in perlite substrate using wastewater from fish and partial use of synthetic fertilizers. Indicatively, Global Warming Potential of these cases was calculated at 21.18 and 40.59 kg CO2-eq/kg of vegetable respectively. The parameter with the greatest impact on most of the environmental indicators was electricity consumption for the operation of the oxygen supply pump for the fish tanks, while greenhouse infrastructure had the greatest impact in Abiotic Depletion and Human Toxicity impact categories. In an alternative production scenario tested where renewable energy sources were used, system impacts were reduced by up to 50% for Global Warming Potential and 86% for Eutrophication impact. The results of this study aspire to constitute a significant milestone in environmental impact assessments of aquaponic production systems and the adoption of more sustainable farming practices.

Carbon Footprint of Greenhouse Production in EU—How Close Are We to Green Deal Goals?

Sustainable greenhouse production has been brought to the forefront as one of the pillars in achieving the objectives set by the Green Deal strategy in 2020, for drastically decreasing net emissions from agriculture. The scope of this review was to capture the current situation regarding the sustainability of greenhouse production in the European Union and to present ways to decrease the carbon footprint. For this reason, a systematic search of studies was conducted, focusing on the investigation of the environmental assessment of conventional greenhouses in EU along with a bibliometric analysis to identify the relationships between the studies. In total, 52 papers were selected for an in-depth analysis that led to addressing the posed research questions. The study reveals that Spain and Italy were the most active countries in the literature for the calculation of the carbon footprint in greenhouses, the value of which showed a large variation per crop and per country and was significantly affected by the use of non-renewable energy sources. It was observed that practical solutions to reduce the carbon footprint of greenhouses have already been implemented and proposed, which indicates a positive inclination towards achieving the Green Deal objectives.

Facilitating sustainable greenhouse production with radiative cooling

Facilitating sustainable greenhouse production with radiative cooling

Solar spectrum management and radiative cooling film for sustainable greenhouse production in hot climates

Solar spectrum management and radiative cooling film for sustainable greenhouse production in hot climates

Opportunities for Implementing Closed Greenhouse Systems in Arid Climate Conditions

The closed greenhouse is an innovative crop system in the horticulture sector, integrating appropriate climate control equipment and optimized techniques to collect, store, and reuse solar energy for heating and/or cooling the greenhouse. This concept aims to improve the crop yield and quality with energy efficient and water-saving technologies. A specific focus on the opportunities of implementing closed greenhouses under arid climate conditions is detailed in this work. Guidelines for selecting appropriate techniques and design parameters are investigated, aiming for profitable and sustainable greenhouse production. This paper provides an overview of the design aspects of the closed greenhouse and a state of the art of its applications in arid areas. Firstly, the microclimate parameters, including temperature, relative humidity (RH), light intensity, and CO2 concentration are introduced. Then, an in-depth focus on the effects of these parameters on crop productivity, water, and energy efficiency are thoroughly discussed. Finally, the limitations of closed greenhouse applications are pointed out as opportunities for further research and development in this emerging agriculture field.

Elevated light intensity compensates for nitrogen deficiency during chrysanthemum growth by improving water and nitrogen use efficiency

Identifying environmental factors that improve plant growth and development under nitrogen (N) constraint is essential for sustainable greenhouse production. In the present study, the role of light intensity and N concentrations on the biomass partitioning and physiology of chrysanthemum was investigated. Four light intensities [75, 150, 300, and 600 µmol m−2 s−1 photosynthetic photon flux density (PPFD)] and three N concentrations (5, 10, and 15 mM N L−1) were used. Vegetative and generative growth traits were improved by increase in PPFD and N concentration. High N supply reduced stomatal size and gs in plants under lowest PPFD. Under low PPFD, the share of biomass allocated to leaves and stem was higher than that of flower and roots while in plants grown under high PPFD, the share of biomass allocated to flower and root outweighed that of allocated to leaves and stem. As well, positive effects of high PPFD on chlorophyll content, photosynthesis, water use efficiency (WUE), Nitrogen use efficiency (NUE) were observed in N-deficient plants. Furthermore, photosynthetic functionality improved by raise in PPFD. In conclusion, high PPFD reduced the adverse effects of N deficiency by improving photosynthesis and stomatal functionality, NUE, WUE, and directing biomass partitioning toward the floral organs.

Environmental Assessment of Improvement Measures to Support More Sustainable Greenhouse Production

Environmental Assessment of Improvement Measures to Support More Sustainable Greenhouse Production

Exploitation of Liquid Digestate as the Sole Nutrient Source for Floating Hydroponic Cultivation of Baby Lettuce (Lactuca sativa) in Greenhouses

Sustainable agriculture relies on replacing fossil-based mineral fertilizers, which are highly cost-energetic to produce, and demand extensive use of scarce natural resources. Today, agronomic practices within the concept of circular economy are emerging and, as such, the exploitation of digestate as a biofertilizer and soil amender is extensively investigated. This study aimed at evaluating the agronomic potential of liquid digestate as the sole nutrient source for hydroponic cultivation of baby lettuce in greenhouses. Growth rate, physiological responses, concentration of secondary metabolites, and nutrient uptake were compared between baby leaf lettuce grown in digestate in concentrations of 5, 10, and 20% diluted in water (either with or without pH adjustment) and in Hoagland solution (control). Results showed that the production yield was negatively correlated with the concentration of the added digestate. Nevertheless, the antioxidant capacity was significantly enhanced in 5 and 10% liquid digestate treatments compared to the control. Additionally, the nutrient composition in the baby leaf lettuce and the reduction in nutrient concentrations in the growth media demonstrated efficient mineral uptake by the plants. Thus, the application of liquid digestate as a fertilizer in hydroponic systems is a promising practice to recover residual resources, leading to the transition towards more sustainable greenhouse production.

Computational Fluid Dynamics Modelling of the Microclimate within the Boundary Layer of Leaves Leading to Improved Pest Control Management and Low-Input Greenhouse

This work aims at using the Computational Fluid Dynamic (CFD) approach to study the distributed microclimate in the leaf boundary layer of greenhouse crops. Understanding the interactions in this microclimate of this natural habitat of plant pests (i.e., boundary layer of leaves), is a prerequisite for their control through targeted climate management for sustainable greenhouse production. The temperature and humidity simulations, inside the greenhouse, were performed using CFD code which has been adapted to simulate the plant activity within each mesh in the crop canopy. The air temperature and air humidity profiles within the boundary layer of leaves were deduced from the local surrounding climate parameters, based on an analytical approach, encapsulated in a Used Defined Function (UDF), and dynamically linked to the CFD solver, a work that forms an innovative and original task. Thus, this model represents a new approach to investigate the microclimate in the boundary layer of leaves under greenhouses, which resolves the issue of the inaccessibility of this area by the conventionnel measurement tools. The findings clearly showed that (i) contrarily to what might be expected, the microclimate parameters within the boundary layer of leaves are different from the surrounding climate in the greenhouse. This is particularly visible during photoperiods when the plant’s transpiration activity is at its maximum and that (ii) the climatic parameters in the leaf boundary layer are more coupled with leaf surfaces than with those of greenhouse air. These results can help developing localized intervention strategies on the microclimate within boundary layer of plant leaves, leading to improved and sustainable pest control management. The developed climatic strategies will make it possible to optimize resources use efficiency.

Light-altering cover materials and sustainable greenhouse production of vegetables: a review

Greenhouse horticulture (protected cropping) is essential in meeting increasing global food demand under climate change scenarios by ensuring sustainability, efficiency, and productivity. Recent advances in cover materials and photovoltaic technologies have been widely examined in greenhouses to improve light transmission and solar energy capture with promoting energy-saving. We review the studies on advanced greenhouse cover materials with variable light transmittance, the effects of which on leaf photosynthesis, physiology, and yield. We provide insights into the potential key biological processes of crops responding to these light changes, specifically light receptors, signal transduction, nutrient biosynthesis pathways (e.g., carotenoids, antioxidant compounds) during fruit development and ripening. A better understanding of greenhouse cover materials with a focus towards energy-efficient cover materials equipped in greenhouse is an opportunity for better yield and higher nutrient products production in vegetables in response to global climate challenges. Interdisciplinary research on the application of novel cover materials in greenhouses and biological investigation of light-induced physiology and nutrient formation in vegetables may promote yield and health attributes for protected cultivation of vegetables with energy use efficiency.

Biochars improve tomato and sweet pepper performance and shift bacterial composition in a peat-based growing medium

We previously observed that the biochars used in this study can replace 15% (v/v) of perlite in a peat-based growing medium (PBGM) without causing any harm to microbial biomass. However, little is known about their impacts on the plant-microbe-soil interactions and crop productivity. Thus, the aim of the present work was to evaluate in greenhouse trials, the effect of substituting perlite in PBGM by three types of biochar on tomato cv. Micro-Tom and sweet pepper cv. Redskin, growth and yield, on their water and fertilizer use efficiency and on the bacterial diversity found in PBGM. Biochars were derived from maple bark pyrolysed at 550 °C (M550) and 700 °C (M700) and from pine chips pyrolysed at 700 °C (P700). Tomato and sweet pepper plants were grown in a greenhouse and fertigated with mineral fertilizer at full or half of the recommended level. Compared to the control without biochar, adding 5, 10 or 15% (v/v) biochar improved plant water use efficiency and increased tomato and sweet pepper fruit dry weight yield respectively, by up to 32% and 54%. Biochar significantly increased N and P uptake efficiency, while reducing loss of NO3− and PO43− in leachates. In PBGM used to grow sweet pepper under full fertigation, the presence of 15% (v/v) M700 or P700 biochars significantly increased bacterial richness probably through the improvement of some ecological micro-niches such as C accessibility. This also allowed the establishment of potential plant growth promoting bacteria particularly Agrobacterium, Cellvibrio and Streptomyces, which showed a positive correlation with plant productivity and the chemical properties of PBGM. Our results suggest that the higher PBGM pH reached by adding 15% (v/v) biochar improved plant growth by increasing carbon, nitrogen and phosphorus availability and by favoring the establishment of plant beneficial bacteria. Therefore, substituting 15% (v/v) of perlite in PBGM with the three tested biochars appears to be a beneficial practice towards sustainable greenhouse production of tomato and sweet pepper, and this practice merit further investigation with other crops such as indeterminate cultivars.

Sustainable greenhouse production with minimised carbon footprint by energy export

Consumer and trade organisations demand year-round healthy diets including fresh, high quality vegetables from local producers. However, greenhouse gas emissions (GHG) of heating high-tech greenhouses in northern countries are higher than transporting vegetables produced in southern Europe in unheated tunnels. The aim of this work was to assess GHG emissions when renewable energy sources were used for heating and cooling a solar collector greenhouse (SCG) in comparison with a conventional greenhouse (RG). Thermal energy generated in the SCG from solar energy was stored in an insulated water tank and different strategies were examined: no reused energy; reused energy; reused energy and excess energy transfer. Based on the semi-closed climate control strategy set in SCG and associated higher CO2 concentrations, higher marketable yields were achieved (+22%) compared to the production in the RG. The results further showed that the cumulative energy demand of the SCG can be lowered by approximately 44% compared to that needed in the RG. The carbon footprint (CF) and the water use efficiency were improved by 24% and 28%, respectively. If excess thermal energy generated by the SCG could be considered as export energy, a negative carbon footprint of −0.7 CO2-eq kg−1 can be reached. The latter case shows that the CF can be reduced to levels of unheated greenhouses. As such, vegetable production in solar collector greenhouses can be more sustainable than in conventional greenhouses since energy and water, as well as fertiliser and associate CO2 emissions, can be saved.

Análisis estratégico de los circuitos alimentarios interandinos: una combinación de dimensiones estructurales y, medición de perfiles socioproductivos

The fruit and vegetable sector in Ecuador has shown promising performance in domestic and international markets. However, this sector has faced problems of a social, economic and productive nature in its structure and articulations that require intervention. The case of the tree tomato agri-food network, located in the central Andean area of Ecuador, is part of this sector. This study shows its main social and productive characteristics, a horizontal and vertical dimensioning, and proposes strategies focused on improving their productive performance. In this study, a systemic methodology was applied aimed at the identification and characterization of stages, agents and activities (primary and support). Additionally, network governance mechanisms were analyzed. The study concluded that inclusion of women, the sense of associativity of processors and distributors, the training of producers in topics related to post-harvest and good agricultural practices would significantly improve the economic performance of the network and encourage greater participation of agents involved. Finally, it was deduced that the network requires increasing the area assigned to the tree tomato crop and the application of sustainable greenhouse production systems to increase yields.

Effect of supplemental lighting on water transport, photosynthetic carbon gain and water use efficiency in greenhouse tomato

Despite supplemental lighting is being increasingly applied in greenhouses to improve crop productivity, there have been few studies investigated effects of supplemental lighting on water movement, water consumption and water use efficiency. To examine the potentials to improve water use efficiency via supplemental lighting, photosynthetic productivity versus water movement under contrasting light treatments was investigated in greenhouse tomato (Solanum lycopersicum L.). In the present study, supplemental lighting by light-emitting diodes (LED) facilitated uniform light distributions along vertical profile canopy. The homogeneous light condition increased stomatal and mesophyll conductance for photosynthetic CO2 uptake, especially at the bottom canopy. Consequently, leaf photosynthetic capacity for carbon acquisition and assimilation was overall improved by supplemental lighting. The improvement in leaf photosynthetic capacity was more pronounced with the increased depth down the vertical profile canopy. Both shoot dry biomass and fresh fruit yield were significantly increased by supplemental lighting. Supplemental lighting by LED altered light condition solely and had no significant effect on the distribution of the water driving force along soil-plant-atmospheric continuum, water transport rate and plant water consumption. Taken together, supplemental lighting maximized photosynthetic productivity and consequently significantly increased water use efficiency, whether based of shoot dry biomass and fresh fruit yield, by 10.2% and 8.7%, respectively. Therefore, we concluded that supplemental lighting by LED is an efficient solution to improve greenhouse crop water use efficiency. The present study provides novel information improving water use efficiency without alterning water consumption for sustainable greenhouse production.

Automation for Water and Nitrogen Deficit Stress Detection in Soilless Tomato Crops Based on Spectral Indices

Water and nitrogen deficit stress are some of the most important growth limiting factors in crop production. Several methods have been used to quantify the impact of water and nitrogen deficit stress on plant physiology. However, by performing machine learning with hyperspectral sensor data, crop physiology management systems are integrated into real artificial intelligence systems, providing richer recommendations and insights into implementing appropriate irrigation and environment control management strategies. In this study, the Classification Tree model was used to group complex hyperspectral datasets in order to provide remote visual results about plant water and nitrogen deficit stress. Soilless tomato crops are grown under varying water and nitrogen regimes. The model that we developed was trained using 75% of the total sample dataset, while the rest (25%) of the data were used to validate the model. The results showed that the combination of MSAVI, mrNDVI, and PRI had the potential to determine water and nitrogen deficit stress with 89.6% and 91.4% classification accuracy values for the training and testing samples, respectively. The results of the current study are promising for developing control strategies for sustainable greenhouse production.

Innovative systems for sustainable greenhouse production

Innovative systems for sustainable greenhouse production

Mitigation of CO2, CH4 and N2O from a fertigated horticultural growing medium amended with biochars and a compost

Biochar effect on greenhouse gases mitigation was mainly studied in amended mineral soils and little information is available for peat-based growing media (PBGMs) used in greenhouse production. We established a 58-d PBGM microcosm incubation study to investigate the effect of different biochars and a compost on the mineralization of carbon (C) and nitrogen (N) and on mitigation of CO2, CH4 and N2O. Biochars and compost were added respectively at a rate of 15% and 4% (v/v) and a weekly mineral N fertilizer was applied. Five biochars were produced from three feedstocks at three pyrolysis temperatures: maple bark 400 °C (M400), 550 °C (M550) and 700 °C (M700); willow chips 400 °C (W400); and pine chips 700 °C (P700). Biochar addition increased C and decreased N availability in fertigated PBGMs. The highest microbial biomass C and N were obtained (p < 0.05) with M400 rich in volatile matter, and with compost treatments. Microbial enzymatic activity was lower (p < 0.05) in maples and W400 treated PBGMs than in P700 and control. Addition of compost and maple biochars produced at 400 °C and 550 °C lowered the microbial metabolic quotient. The highest mitigation efficiency of CO2 was obtained with M550 which released in 58-d, 50% less than other treatments. The total cumulative CH4 emission was also 21% lower in maple PBGMs than in control or P700. The total cumulative N2O emission was reduced by 66% by the addition of alkaline biochars (M400, M550, M700 and W400) in the PBGM without compost. This mitigation can be associated with the important ammonium adsorption by these biochars which can slow the nitrification process, or to a probable increase in the N2/N2O ratio. Compost addition had no effect on the N2O fluxes from all treatments. This work indicates that biochars can be favorably used as an amendment to PBGMs for the development of a sustainable greenhouse production.

Assessment of energy consumption in organic tomato greenhouse production – a case study

Greenhouse production has increased over the last decades in the Mediterranean region. Greenhouses allow protecting crops from adverse climate conditions, creating microclimate conditions appropriate for obtaining high production with high quality all over the year. However, greenhouse production is generally associated with high environmental impacts due to the use of high amounts of resource inputs and the high quantity of waste generated. Sustainable greenhouse production is nowadays a goal and can be achieved by using appropriate technologies such as innovating crop practices and environmental control techniques allowing reducing agro-chemicals, water, and energy consumption. Organic farming is based on methods and practices that try to protect the environment (soil, water, air), which includes limitation on the use of synthetic pesticides and fertilizers and the use of on-site resources, such as livestock manure for fertilizer. Demand for food produced without using agro-chemicals has increased; usually these products are sold at high price and associated to a particular nutritional value, taste and health. It is generally associated with lower yield and better quality. Greenhouse organic farming is not widely applied as farmers believe that yields are strongly reduced. However, there is a market opportunity to organic farming as a result of higher product prices and consumers demand. In order to compare the overall efficiency of crop farming systems, it is vital to consider energy consumption and efficiency. In this work, a case study is analysed in terms of energy consumption and greenhouse gas emissions (GHG). The data were obtained directly from the grower and the main objective of this work was to characterize the organic greenhouse production system. The most important inputs were identified and compared with others obtained with conventional greenhouse production. Results showed that organic greenhouse uses less energy ha-1 and t-1 of produced tomatoes than the conventional greenhouses.

Technological and ecological approaches to design and manage sustainable greenhouse production systems

Protected cultivation or Controlled Environment Agriculture (CEA) system has increased tenfold in the last 25 years thanks to tremendous scientific and technical breakthroughs, mainly directed to increasing crop yields and adapting to tough ambient conditions. Currently, greenhouse areas are still spreading and the CEA system is one of the keystones for the agriculture forecasting scenario. However, the environmental acceptability of this very intensive agro-ecosystem is now being questioned. Energy inputs are source of the main economic and environmental weakness, especially for high-tech greenhouses, where IPM is well-established. Pesticides, common in low-cost greenhouses systems, are a major barrier-to IPM. To design and manage more robust CEA systems, both technological and ecological approaches have been chosen. This allowed for increased consideration of IPM issues among global greenhouse engineering innovation and better use of greenhouse system capacities to enhance dedicated IPM high-tech tools and management practices. On the other hand, ecological concepts were used to determine and characterize complex biotic interactions that lead to question the tenant of biological control as soon as IPM is implemented in greenhouses with sub-optimum physical pest control means. More specifically, microclimate at the boundary layer level has been investigated both from a physical and biological point of view in order to determine the best climate preferences of the main pests and beneficials. By the same token, the efficiency of diverse biocontrol plants to provide accurate shelter to natural enemies has been assessed

USE OF NATURAL AND ARTIFICIAL LIGHT IN HORTICULTURE - INTERACTION OF PLANT AND TECHNOLOGY

In intensive horticultural cultivation natural light levels often limit crop production during several periods. For an optimum plant production and product quality light intensity, spectrum and photoperiod have to be adapted to the needs of the crops at every moment. Light has to be optimised together with all other growth factors like temperature, humidity and CO2. For a sustainable greenhouse production the use of freely available sunlight has to be preferred. New transparent greenhouse covering materials, like ETFE, glass with new anti-reflection coatings or materials with micro-surface structures, transmit a very high amount of light into the greenhouse. Other new materials are able to scatter the incoming light and make it diffuse. Diffuse light penetrates deeper into the canopy, increases light interception by the crop, influences micro-climate and increases crop production by 6.5-9.2% in The Netherlands, the potential in lower latitudes is even higher. Other materials manipulate light spectrum. Photoselective nettings have been developed in different colours influencing morphogenesis and crop production. Fluorescent plastic films combine effects on morphogenesis with high light transmission, especially important for higher latitudes. When sunlight is optimized it can still be necessary to add artificial light to ensure a year-round supply of horticultural products. There is still room for improving the crop energy efficiency under artificial lighting by changing duration and intensity of lighting, different growing systems and plant densities. Since artificial lighting requires a high amount of energy, new artificial lighting systems have been developed, such as interlighting and light emitting diodes (LED). LED give the possibility for true light spectrum control in the future. The (partial) replacement of HPS lamps by LED systems is currently under investigation in Dutch greenhouses. Integration in current growing systems has full attention. In order to reach a high sustainable and economic beneficial production the factor light has to be integrated and optimized within the total horticultural system