IMPROVING ENERGY EFFICIENCY IN PROTECTED CROPPING BY EXPLOITING PLANT RESPONSES TO SOLAR ULTRAVIOLET RADIATION

Lead Research Organisation: Lancaster University
Department Name: Lancaster Environment Centre

Abstract

Horticulture, the production of fresh fruit, vegetables, salads etc, is often overlooked in discussions of food security yet is vital to avoid hidden hunger due to shortage of micro-nutrients. Delivering a year-round supply of fresh produce for N Europe involves local crops produced in heated glasshouses, or crops imported from the Mediterranean basin and beyond. In either case, energy is a major commercial constraint (costs and C footprint) and any technology that reduces energy use is immediately attractive, commercially and environmentally. This project addresses this energy challenge in protected cropping by delivering fundamental insights into a newly recognized crop response to the ultraviolet (UV) radiation in sunlight.

Previous research at Lancaster contributed to the development of new UV-transparent (UV-T) crop-covers used in protected crops. Growers using UV-T cladding report that crops mature earlier than under conventional cladding, and they attribute this to the crop being warmer under UV-T covers. We have tested this and shown for the first time that additional UV exposure within a physiologically relevant range results in small but significant increases (0.5-1.7C) in leaf temperature. This is caused by UV decreasing stomatal conductance and transpirational cooling, thereby warming the leaves. This CASE studentship will investigate this effect of UV on crop temperature in a range of commercial protected crops, both fruit crops (e.g. strawberry, tomato, pepper, cucumber) and leafy crops (e.g. basil, coriander, lettuce, rocket). The student will go on to investigate in selected crops whether UV during the day also affects crop temperature at night, and whether effects are confined to leaves, or also occur in other tissues.

Arid's commercial assessment is that objective scientific evidence that UV-T covers leads to increased crop temperature would be highly attractive to growers, especially for early and late crops in the Mediterranean rim. The new understanding obtained through the project will also inform the design of new energy saving claddings. In the longer term, this understanding may also allow improved energy use in crops lit by LEDs.

The project will start at Lancaster (Years 1 & 2) studying temperature and physiological responses in a range of crops (as above). During Years 3 or 4 the student will spend at least six months placement at Arid's base in Antalya, Turkey. We believe an international dimension is essential for understanding the complexities of modern commercial protected crop management. Also, the impact from this project will most likely be applied most quickly in the environments like Turkey, where any temperature benefit would be a major commercial advantage for UK-manufactured UV-transparent plastics.

This collaboration between Arid Agritec and LEC provides an immediate opportunity to field test academic findings at commercial field sites. The collaboration also provide the student with a unique opportunity to undertaken research across the range of scales (laboratory, glasshouse, field) and different research environments, and with an obvious, immediate route to exploitation.

The student will have contact with a range of agri-business professionals, including growers, technicians, consultants and supply chain personnel. Such interactions will ensure the student understands the needs of the industry, and provide training in business strategy. That understanding will be underpinned at Lancaster by formal skills training consistent with the Researcher Development Statement developed by Vitae. The student will also benefit from a supervisory team (Prof Nigel Paul and Dr Ian Dodd at Lancaster, Dr Jason Moore at Arid) with a total of 60 years research experience in plant science across the academic-commercial spectrum. These are important contexts for the development of the student's wider skills base as well as for the successful commercialization of their research.

Studentship Projects

Project Reference Relationship Related To Start End Student Name
BB/M017109/1 30/09/2015 29/09/2019
1653788 Studentship BB/M017109/1 30/09/2015 29/09/2019 Tom Williams
 
Description Ultraviolet (UV) radiation induced partial stomatal closure was evident in a range of experimental environments. In tightly controlled climate cabinet experiments, applying a range of acute (90 minute) UV treatments, identified a non-linear UV irradiance response that decreased stomatal conductance while increasing leaf temperature and instantaneous water use efficiency (WUEi). In longer term controlled environment experiments, and in polytunnels experiments in the UK and Turkey, the same UV-induced partial stomatal closure resulted in enhanced leaf temperature (up to 2.2°C) in UV+ polytunnels compared to UV-, demonstrating the consistency of the stomatal and temperature response although WUEi was not significantly because assimilation rate and transpiration rate decreased proportionately. In the UK, changeable UV radiation conditions due to variable cloud cover, led to a reversal of the stomatal response between UV treatments. Ultimately leaf temperature decoupled from stomatal conductance, both variables increasing simultaneously, caused by greater radiation loading in UV+ polytunnels. This was investigated in polytunnels in Turkey by analysing the net radiation balance between UV+ and UV- polytunnels in terms of upwelling and downwelling solar and far infrared radiation. Downwelling and net solar radiation were significantly greater in UV+ polytunnels than UV-, but vice versa for downwelling and net far infrared radiation, with an overall balance of greater net total radiation in UV+ polytunnels. This explains the cause of radiative heating in UV+ polytunnels compared to UV- and why leaf temperature decoupled from stomatal conductance when UV radiation levels were reduced by cloud. Thus enhanced leaf temperature in UV-transparent polytunnels is caused by concurrent UV-induced partial stomatal closure and radiative heating resulting from net radiation imbalance, with stomatal closure dominant when total radiation is low but vice versa when total radiation is high. These effects depend on the UV and total radiation transmission properties of the specific plastics used, of which there is a vast range available.
Exploitation Route Further investigation of the the impacts on water use efficiency at the whole plant level could be undertaken for a greater understanding of that aspect of this work, which would impact horticultural production of crops and water security in locations where water availability is limited (e.g. around the Mediterranean). Commercial growers can now see that using UV transparent plastic claddings for polytunnels can extend the growing season for early and late crops in the Mediterranean rim. These finding may also influence teh use of UV LEDs in protected horticultural production in terms of managing optimal leaf temperature and the possible impacts on water use efficiency.
Sectors Agriculture, Food and Drink,Environment

 
Description This PhD studentship was co-designed and co-developed with our industrial partner, Arid Agritec Ltd. That collaboration continues to flourish, both through this funding and other projects. The PhD student benefitted from two periods of research 'on the ground' in the growing areas in Turkey where the effects of UV-transparent cladding materials on leaf temperature was first reported by growers. That work provided a useful 'bridge' between the original fundamental research of the project and its applied aspects. The very successful presentation of the work at a conference focussed on innovation in horticulture [III International Symposium on Innovation and New Technologies in Protected Cultivation - International Horticultural Congress 2018] was another strong step along the 'pathway to impact'. Looking ahead, preparation of first academic publications from the project are now well-advanced. That is our initial priority as, in our experience, publication in the peer reviewed literature has value in demonstrating objectivity in data with applied relevance. Beyond that, we see the on-going links with Arid Agritec as the fundamental route to impact since they (i) have direct contact with and routes to disseminate to the growers who are the end-users of this research and (ii) have the means to explore how our new observations can be integrated in to innovative approaches to the protected production of horticultural crops. That might include the development of new cladding materials, for example through links with the collaborative innovate UK project led by the company.
First Year Of Impact 2018
Sector Agriculture, Food and Drink
Impact Types Societal,Economic

 
Title Antalya (Turkey) polytunnel dataset 2018 
Description Data collected on leaf temperature, stomatal conductance, transpiration rate, assimilation rate, intracellular carbon dioxide (with instantaneous water use efficiency calculated from these) with a LI-6400 (LI-COR), also leaf temperature day & night (infrared thermometer), and leaf thickness growth rate and stem elongation rate , in custom made polytunnels to assess the response of tomato (cv. Money Maker and a commercial Turkish cultivar) to solar UV radiation over 1 week. 3x polytunnels were clad in UV blocker plastic and 3x polytunnels in UV transparent plastic cladding. After 1 week some plants (others remained as a control) were swapped into the opposite UV treatment polytunnel (i.e. from UV blocker to UV transparent) and the same parameters measured 24 hours later to determine the effect of 'transfer' between UV environments. 
Type Of Material Database/Collection of data 
Year Produced 2020 
Provided To Others? Yes  
Impact None, no response detected because UV radiation levels were insufficient in October. 
 
Title Antalya (Turkey) polytunnel dataset 2019 
Description Data collected on leaf temperature, stomatal conductance, transpiration rate, assimilation rate, intracellular carbon dioxide (with instantaneous water use efficiency calculated from these) with a LI-6400 (LI-COR), also leaf temperature day & night (infrared thermometer), in custom made polytunnels to assess the response of tomato (a commercial Turkish cultivar) to solar UV radiation over 1 week. 3x polytunnels were clad in UV blocker plastic and 3x polytunnels in UV transparent plastic cladding. Additionally, the radiation balance within UV+/UV- polytunnels was investigated with a 4-way net radiometer to understand whether this may also be causing a difference in leaf temperature between the UV+/UV- polytunnel environments. 
Type Of Material Database/Collection of data 
Year Produced 2020 
Provided To Others? Yes  
Impact Statistically significant leaf temperature increase, due to significant stomatal conductance and transpiration rate reductions, were identified. Assimilation rate also decreased significantly resulting in little difference between treatments for water use efficiency as both transpiration rate and assimilation rate reduced proportionately. Intracellular carbon dioxide also exhibited little difference between treatments. Downwelling solar radiation was significantly greater in UV+ polytunnels although downwelling far infrared radiation was significantly greater in UV- polytunnels. These differences in solar radiation far outweighed the differences in far infrared radiation, thus net radiation balance was significantly greater in the UV+ polytunnels, which can help explain some of the leaf warming caused in UV+ polytunnels, which acts in conjunction with UV radiation causing partial stomatal closure. The influence of each in dependent on the external UV radiation levels present, and the plastics used to clad polytunnels which affects the differences in radiation balance within. These data demonstrate that the use of UV-transparent claddings (UV+) can extend the growing season by enhancing crop temperature at the start/end of the growing season. 
 
Title Climate cabinet dataset 
Description Data collected with LI-6400 infrared gas analyser (LI-COR) in a Snijder climate cabinet to assess the irradiance/dose response of tomato (cv. Money Maker) to UV radiation applied at various different irradiances for 90 mins. Data collected on leaf temperature, stomatal conductance, transpiration rate, assimilation rate, intracellular carbon dioxide and subsequent calculation of instantaneous water use efficiency. 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
Impact Allowed determination of the UV irradiance/dose response relationship in terms of the above mentioned parameters. Leaf temperature and water use efficiency increased non-linearly, whereas assimilation rate and intracellular carbon dioxide decreased decreased linearly. The findings could lead to the use of UV radiation in protected horticulture through short term application to increase leaf temperature and water use efficiency. 
 
Title Controlled environment room dataset (2019) 
Description Similar to the work conducted in polytunnels in Antalya (Turkey), data collected on leaf temperature, stomatal conductance, transpiration rate, assimilation rate, intracellular carbon dioxide (with instantaneous water use efficiency calculated from these) with a LI-6400 (LI-COR) to assess the response of tomato (cv. Money Maker) to UV radiation over 1 week in a controlled environment. After 1 week some plants (others remained as a control) were swapped into the opposite UV treatment regime (i.e. from UV+ to UV-) and the same parameters measured 24 hours later to determine the effect of 'transfer' between UV environments. 
Type Of Material Database/Collection of data 
Year Produced 2020 
Provided To Others? Yes  
Impact Statistically significant leaf temperature increase, due to significant stomatal conductance and transpiration rate reductions, were identified. Assimilation rate also decreased significantly resulting in little difference between treatments for water use efficiency as both transpiration rate and assimilation rate reduced proportionately. Intracellular carbon dioxide also exhibited little difference between treatments. These data demonstrate that the use of UV radiation can enhance crop temperature where it is required. 
 
Title Lancaster Environment Centre polytunnel dataset 2018 
Description Data collected with a porometer (stomatal conductance,) infrared thermometer and thermal camera (leaf temperature) in custom made polytunnels to assess the response of tomato (cv. Money Maker) to solar UV radiation over 1 week and on a single night. 2x polytunnels were clad in UV blocker plastic and 2x polytunnels in UV transparent plastic cladding. After 1 week some plants (others remained as a control) were swapped into the opposite UV treatment polytunnel (i.e. from UV blocker to UV transparent) and data collected with a LI-6400 (LI-COR) on leaf temperature, stomatal conductance, transpiration rate, assimilation rate, intracellular carbon dioxide and subsequent calculation of instantaneous water use efficiency, 24 hours later to determine the effect of 'transfer' between UV environments. This was repeated 4 times. 
Type Of Material Database/Collection of data 
Year Produced 2020 
Provided To Others? Yes  
Impact Statistically significant reduction in stomatal conductance and increase in leaf temperature was observed. When UV radiation levels were reduced by cloud cover both stomatal conductance and leaf temperature were greater in response to UV radiation than when it was excluded, gradually decoupling from each other, indicating leaf warming unrelated to UV-induced stomatal closure was occurring. This lead to investigation of the cause of this 'additional or separate' leaf warming, hypothesised to result from differences in radiation balance between UV+/UV- polytunnels, in polytunnels in Antalya (Turkey). 
 
Description Collaboration with horticulture research in the USA 
Organisation Arid Agritec Ltd
Country United Kingdom 
Sector Private 
PI Contribution Researchers at the College of Agricultural Sciences at Penn Sate University, the Department of Horticulture at Michigan State University and others have been funded by USDA to investigate the use of plastics cladding materials in soft-fruit production (https://www.tunnelberries.org/) With the industrial partners on this studentship, Arid Agritech Ltd., we have offered advice and support to our US colleagues, who had little previous experience of cladding materials or crop photobiology.
Collaborator Contribution Our colleagues at the College of Agricultural Sciences at Penn Sate University, the Department of Horticulture at Michigan State University and othersand other US institutions have undertaken a major body of applied research in to the use of different cladding materials in soft-fruit production, funded by USDA . Their insights in a very different growing environment has informed our own research, both how cladding affect pest control and pesticide degradation (Understanding pesticide photodegradation & persistence in protected-crop environments: Ref 1096682) and leaf temperature (Improving energy efficiency in protected cropping by exploiting plat responses to solar ultraviolet radiation: ref 1653788).
Impact There have been no UK outputs
Start Year 2016
 
Description Collaboration with horticulture research in the USA 
Organisation Michigan State University
Country United States 
Sector Academic/University 
PI Contribution Researchers at the College of Agricultural Sciences at Penn Sate University, the Department of Horticulture at Michigan State University and others have been funded by USDA to investigate the use of plastics cladding materials in soft-fruit production (https://www.tunnelberries.org/) With the industrial partners on this studentship, Arid Agritech Ltd., we have offered advice and support to our US colleagues, who had little previous experience of cladding materials or crop photobiology.
Collaborator Contribution Our colleagues at the College of Agricultural Sciences at Penn Sate University, the Department of Horticulture at Michigan State University and othersand other US institutions have undertaken a major body of applied research in to the use of different cladding materials in soft-fruit production, funded by USDA . Their insights in a very different growing environment has informed our own research, both how cladding affect pest control and pesticide degradation (Understanding pesticide photodegradation & persistence in protected-crop environments: Ref 1096682) and leaf temperature (Improving energy efficiency in protected cropping by exploiting plat responses to solar ultraviolet radiation: ref 1653788).
Impact There have been no UK outputs
Start Year 2016
 
Description Collaboration with horticulture research in the USA 
Organisation Penn State University
Country United States 
Sector Academic/University 
PI Contribution Researchers at the College of Agricultural Sciences at Penn Sate University, the Department of Horticulture at Michigan State University and others have been funded by USDA to investigate the use of plastics cladding materials in soft-fruit production (https://www.tunnelberries.org/) With the industrial partners on this studentship, Arid Agritech Ltd., we have offered advice and support to our US colleagues, who had little previous experience of cladding materials or crop photobiology.
Collaborator Contribution Our colleagues at the College of Agricultural Sciences at Penn Sate University, the Department of Horticulture at Michigan State University and othersand other US institutions have undertaken a major body of applied research in to the use of different cladding materials in soft-fruit production, funded by USDA . Their insights in a very different growing environment has informed our own research, both how cladding affect pest control and pesticide degradation (Understanding pesticide photodegradation & persistence in protected-crop environments: Ref 1096682) and leaf temperature (Improving energy efficiency in protected cropping by exploiting plat responses to solar ultraviolet radiation: ref 1653788).
Impact There have been no UK outputs
Start Year 2016
 
Description Commercial development of new understanding of pesticide photodegradation 
Organisation Arid Agritec Ltd
Country United Kingdom 
Sector Private 
PI Contribution Arid Agritech were the commercial partner in the CASE studentship that was funded through this award. Since the completion of the project they have continued discussion with Dr Cris Halsall, co-supervisor on this project, about the commercial development of the learning gained from the project. The fundamental science is that which emerged from the project, primarily in relation to Dr Halsall's research in the pesticide photochemistry. Dr Halsall has provided that highly specialist input to Arid's development of commercial applications, including the scope for a patent. Dr Halsall has been instrumental in developing first draft patent document. This on-going collaboration has led to a application to Innovate UK to develop an App-based system for growers world-wide to predict pesticide degradation in protected crops, including relevant IP protection etc. They anticipate a decision by the end of March 2018.
Collaborator Contribution Arid Agritech were the commercial partner in the CASE studentship that was funded through this award. Since the completion of the project they have continued discussion with Dr Cris Halsall, co-supervisor on this project, about the commercial development of the learning gained from the project. The bring a clear commercial focus, driven by their strong presence in export markets in Turkey and the Middle East. That has led them to identify the continuing issue of crops being rejected for export due to pesticide residues exceeding the required limit, an issue that may be increased by growers using a wider range of cladding plastics. This commercial insight led Arid to propose the development of an App-based systems by which growers could predict residue persistence in different growing systems (e.g. different plastics, different locations or different seasons). It has been Arid who have led the application to Innovate UK to develop an App-based system for growers world-wide to predict pesticide degradation in protected crops, including relevant IP protection etc. They anticipate a decision by the end of March 2018
Impact The key outputs to date have been the application for Innovate funding, with a patent application still at the draft stage.
Start Year 2015
 
Description III International Symposium on Innovation and New Technologies in Protected Cultivation - International Horticultural Congress 2018 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presentation titled 'Ultraviolet (UV) transparent plastic claddings warm crops and improve water use efficiency' given to disseminate the findings of the PhD at that point in time. This was my first conference presentation. I won a prize for the best oral presentation in my symposium. A related peer reviewed conference paper was also published. This also instigated discussions with members of the audience regarding this work.
Year(s) Of Engagement Activity 2018
URL https://www.ishs.org/symposium/663
 
Description Photobiology Workshop (Lancaster University) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Academics, business people and students, from as far away as London and Middlesbrough, gathered at the Lancaster Environment Centre (LEC) on the afternoon of the 6th February for the N8 Agrifood-sponsored workshop Lighting the Way to Resource Use Efficiency, which showcased different technologies for manipulating the light environment which crops are exposed to. International visitors from Pennsylvania State University (USA) and Cukurova University (Turkey) were able to join the meeting via video-conference. The workshop was held as part of an N8 Local Pump-Priming Award made by Lancaster University, to foster collaboration with the University of Liverpool and Stockbridge Technology Centre (Yorkshire).
Following a brief introduction by host Professor Ian Dodd (LEC), Professor Nigel Paul (LEC) provided a historical perspective on light manipulation in cropping systems, with projections into the future. Drawing on his archives of previous research, he convinced the audience of his ability to accurately predict the future use of light-emitting diodes (LEDs) in protected horticulture (give or take 5 years). A highlight was his video of "aphids dancing" in response to UV exposure.
Dr Miguel de Lucas Torres (Durham) providing a fascinating insight into the molecular mechanisms by which plants perceive lighting cues, with changes in gene expression orchestrated by transcription factors and nuclear chromatin modification. Dr Rhydian Beynon-Davies (Stockbridge) showcased results from some of the unique lighting facilities at his site, demonstrating that light's influence extends below-ground, with substantial modification of rooting patterns (and transplant success) when seedlings are exposed to light regimes of different spectral quality.
Dr Kathleen Demchak (Pennsylvania) reported the initial results of the TunnelBerries project, which uses different plastic claddings to manipulate the light environment berry crops are exposed to. In addition to effects on crop yields and quality, certain claddings reduced the levels of some insect pests to manageable levels in the absence of pesticide applications. Dr Wagdy Sobeih (Arid Agritech) also discussed his company's ambitions to develop new plastic claddings to best suit specific crops, based on a wealth of experience in commercial protected horticulture in the Middle East, where increasing crop water use efficiency is a priority for growers.
Following enthusiastic discussion at the coffee break (with cakes the colour of some of the light regimes previously discussed !), the audience reconvened for the Practising Photobiologists session, allowing Lancaster-registered research students to briefly present their work:
Tom Williams outlined his research on UV effects on leaf gas exchange of tomato crops
Phoebe Sutton discussed her work with MayBarn Consultancy on developing bespoke lighting regimes for high value herbs
Hao Zhou presented his measurements of crop yield, gas exchange and volatile emissions, collected during his research placement at Stockbridge last summer, while a student at the University of York.
Several discussion points were considered in the closing remarks, with informal discussions suggesting sufficient interest in a follow-up meeting in Durham next year.
While resource use efficiency may be only one aspect that growers consider when developing horticultural cropping systems, it became apparent they could have their cake and eat it too - with increased yields, decreased costs and increased resource use efficiency all achievable following sufficient research.
Year(s) Of Engagement Activity 2019