ArticlePublisher preview available

Optimum root zone temperature of photosynthesis and plant growth depends on air temperature in lettuce plants

Authors:
Namiko Yamori
Namiko Yamori
Namiko Yamori
  • This person is not on ResearchGate, or hasn't claimed this research yet.
Christopher P. Levine at The University of Tokyo
Christopher P. Levine
Neil S. Mattson
Neil S. Mattson
Neil S. Mattson
  • This person is not on ResearchGate, or hasn't claimed this research yet.
Wataru Yamori at The University of Tokyo
Wataru Yamori
Read publisher preview
Download citation
To read the full-text of this research, you can request a copy directly from the authors.

Abstract and Figures

Key message The present study clearly showed that the optimum root zone temperature of photosynthesis and plant growth was affected by air temperature, and that optimization of root zone temperature depending on an air growth temperature by cooling systems could lead to improvement of plant production. Abstract Temperature is one of the critical factors affecting plant growth and yield production. Both air and root zone temperatures can strongly affect growth and development of plants. However, studies on the effects of root zone temperature on plant growth parameters along with air temperature are still limited. In the present study, the effects of air and root zone temperature on plant growth, physiological parameters and photosynthetic characteristics of lettuce plants were investigated to optimize the air and root zone temperature to achieve the best growth conditions for lettuce plants. Two air temperature treatments (30/25 and 25/20 °C at day/night temperature) and five root zone temperature treatments (15, 20, 25, 30 and 35 °C) were applied in this study. The present study showed that the maximum plant growth of lettuce plants was higher in air temperatures at 30/25 °C than in 25/20 °C. When the plants were grown at an air temperature of 30/25 °C, the optimum root zone temperature appeared to be 30 °C. However, when the plants were grown at an air temperature of 25/20 °C, the optimum root temperature decreased and appeared to be 25 °C. Furthermore, plants grown under air temperature of 30/25 °C showed greater CO2 assimilation rate, stomatal conductance, electron transport rate (ETR) at high light, and lower non-photochemical quenching (NPQ) at high light than those of 25/20 °C. These results suggest that it is necessary to control and adjust the root zone temperature based on the air temperature.
Short-term effect of root zone temperatures on CO2 assimilation rate (A, D), stomatal conductance (B, E), dark respiration rate (C), electron transport rate (ETR, F) and non-photochemical-quenching (NPQ, G) in plants grown at air temperature of 25/20 °C (A, B, C) or 30/25 °C. The photosynthetic characteristics were measured at growth light intensity of 200 µmol m⁻² s⁻¹ (A, B, C) or high light intensity of 800 µmol m⁻² s⁻¹ (D, E, F, G). Error bars represent ± SE of mean (n = 5). Different letters indicate significant differences among different root zone temperature at P < 0.05 by using ANOVA Tukey analysis test. * indicates significant differences between the two different growing air temperature at P < 0.05 by using Student's t-test
Short-term effect of root zone temperatures on CO2 assimilation rate (A, D), stomatal conductance (B, E), dark respiration rate (C), electron transport rate (ETR, F) and non-photochemical-quenching (NPQ, G) in plants grown at air temperature of 25/20 °C (A, B, C) or 30/25 °C. The photosynthetic characteristics were measured at growth light intensity of 200 µmol m⁻² s⁻¹ (A, B, C) or high light intensity of 800 µmol m⁻² s⁻¹ (D, E, F, G). Error bars represent ± SE of mean (n = 5). Different letters indicate significant differences among different root zone temperature at P < 0.05 by using ANOVA Tukey analysis test. * indicates significant differences between the two different growing air temperature at P < 0.05 by using Student's t-test
… 
Lettuce (Lactuca sativa L. var. longifolia) grown under different growth temperature condition at 5 weeks after sowing. Plants were grown at air temperature of 25/20 or 30/25 °C, and at root zone temperature of 15, 20, 25, 30 or 35 °C. Plants in the same horizontal line were grown under the same air temperature, whereas plants in the same vertical line were grown under same root zone temperature
Lettuce (Lactuca sativa L. var. longifolia) grown under different growth temperature condition at 5 weeks after sowing. Plants were grown at air temperature of 25/20 or 30/25 °C, and at root zone temperature of 15, 20, 25, 30 or 35 °C. Plants in the same horizontal line were grown under the same air temperature, whereas plants in the same vertical line were grown under same root zone temperature
… 
Long-term effect of root zone temperature on plant growth characteristics for 5 weeks after sowing seeds in plants grown at air temperature of 25/20 or 30/25 °C. (A) root dry weight (DW), (B) shoot DW, (C) shoot/root ratio, (D) leaf number, (E) total leaf area and (F) leaf mass per area (LMA). Error bars represent ± SE of mean (n = 5). Different letters indicate significant differences among different root zone temperature at P < 0.05 by using ANOVA Tukey analysis test. * indicates significant differences between the two different growing air temperature at P < 0.05 by using Student's t-test
Long-term effect of root zone temperature on plant growth characteristics for 5 weeks after sowing seeds in plants grown at air temperature of 25/20 or 30/25 °C. (A) root dry weight (DW), (B) shoot DW, (C) shoot/root ratio, (D) leaf number, (E) total leaf area and (F) leaf mass per area (LMA). Error bars represent ± SE of mean (n = 5). Different letters indicate significant differences among different root zone temperature at P < 0.05 by using ANOVA Tukey analysis test. * indicates significant differences between the two different growing air temperature at P < 0.05 by using Student's t-test
… 
Long-term effect of root zone temperatures on CO2 assimilation rate (A), stomatal conductance (B) and dark respiration rate (C) in plants grown at air temperature of 25/20 or 30/25 °C. The photosynthetic characteristics were measured at growth light intensity of 200 µmol m⁻² s⁻¹. Error bars represent ± SE of mean (n = 5). Different letters indicate significant differences among different root zone temperature at P < 0.05 by using ANOVA Tukey analysis test. * indicates significant differences between the two different growing air temperature at P < 0.05 by using Student's t-test
Long-term effect of root zone temperatures on CO2 assimilation rate (A), stomatal conductance (B) and dark respiration rate (C) in plants grown at air temperature of 25/20 or 30/25 °C. The photosynthetic characteristics were measured at growth light intensity of 200 µmol m⁻² s⁻¹. Error bars represent ± SE of mean (n = 5). Different letters indicate significant differences among different root zone temperature at P < 0.05 by using ANOVA Tukey analysis test. * indicates significant differences between the two different growing air temperature at P < 0.05 by using Student's t-test
… 
Long-term effect of root zone temperatures on leaf ascorbic acid content (A) and nitrate content (B) in plants grown at air temperature of 25/20 or 30/25 °C. Error bars represent ± SE of mean (n = 5). Different letters indicate significant differences among different root zone temperature at P < 0.05 by using ANOVA Tukey analysis test. * indicates significant differences between the two different growing air temperature at P < 0.05 by using Student's t-test
Long-term effect of root zone temperatures on leaf ascorbic acid content (A) and nitrate content (B) in plants grown at air temperature of 25/20 or 30/25 °C. Error bars represent ± SE of mean (n = 5). Different letters indicate significant differences among different root zone temperature at P < 0.05 by using ANOVA Tukey analysis test. * indicates significant differences between the two different growing air temperature at P < 0.05 by using Student's t-test
… 
Figures - available from: Plant Molecular Biology
This content is subject to copyright. Terms and conditions apply.
A preview of this full-text is provided by Springer Nature.
Learn more
Content available from Plant Molecular Biology
This content is subject to copyright. Terms and conditions apply.
Vol.:(0123456789)
1 3
Plant Molecular Biology (2022) 110:385–395
https://doi.org/10.1007/s11103-022-01249-w
Optimum root zone temperature ofphotosynthesis andplant growth
depends onair temperature inlettuce plants
NamikoYamori1· ChristopherP.Levine2· NeilS.Mattson2· WataruYamori1
Received: 30 November 2021 / Accepted: 30 January 2022 / Published online: 15 February 2022
© The Author(s), under exclusive licence to Springer Nature B.V. 2022
Abstract
Key message The present study clearly showed that the optimum root zone temperature of photosynthesis and plant
growth was affected by air temperature, and that optimization of root zone temperature depending on an air growth
temperature by cooling systems could lead to improvement of plant production.
Abstract Temperature is one of the critical factors affecting plant growth and yield production. Both air and root zone tem-
peratures can strongly affect growth and development of plants. However, studies on the effects of root zone temperature
on plant growth parameters along with air temperature are still limited. In the present study, the effects of air and root zone
temperature on plant growth, physiological parameters and photosynthetic characteristics of lettuce plants were investigated
to optimize the air and root zone temperature to achieve the best growth conditions for lettuce plants. Two air temperature
treatments (30/25 and 25/20°C at day/night temperature) and five root zone temperature treatments (15, 20, 25, 30 and
35°C) were applied in this study. The present study showed that the maximum plant growth of lettuce plants was higher in
air temperatures at 30/25°C than in 25/20°C. When the plants were grown at an air temperature of 30/25°C, the optimum
root zone temperature appeared to be 30°C. However, when the plants were grown at an air temperature of 25/20°C, the
optimum root temperature decreased and appeared to be 25°C. Furthermore, plants grown under air temperature of 30/25°C
showed greater CO2 assimilation rate, stomatal conductance, electron transport rate (ETR) at high light, and lower non-
photochemical quenching (NPQ) at high light than those of 25/20°C. These results suggest that it is necessary to control
and adjust the root zone temperature based on the air temperature.
Keywords Air temperature· Root zone temperature· Lettuce· Plant growth· Photosynthesis
Introduction
Cultivation in a closed-type plant factory with artificial light-
ing enables a year-round production of crops with a stable
yield and uniform quality. This contrasts with cultivation in
fields and greenhouses (sunlight-type plant factories) where
environmental fluctuations can reduce crop yield, uniform-
ity, and quality. Therefore, closed-type plant factories are
expected to be applicable to harsh environments inadequate
for crop production and lead to improvement of global food
security (Kozai, 2013; Anpo etal., 2019). However, the
high electricity costs of running closed-type plant factories
diminishes the benefit of improved sales and consequently
hinders new entry into the business (Kozai and Niu, 2020).
Identifying optimal cultivation methods to maximize crop
yield while reducing input costs could enhance the benefits
of closed-type plant factories and lead to an expansion in
operations.
Among the various environmental factors, temperature
is an important factor for the growth and development of
plants (Levitt, 2012b). There are numerous studies on plant
growth and photosynthesis in response to air temperature
(Berry and Bjorkman 1980; Shabala etal., 2012; Wise etal.,
2004; Kratsch and Wise, 2000; Yamori etal. 2014; Way &
Yamori 2014). High temperatures can have either reversible
effects on plant function or irreversible damaging effects
Namiko Yamori and Christopher P. Levine equally contributed to
this work.
* Wataru Yamori
yamori@g.ecc.u-tokyo.ac.jp
1 Institute forSustainable Agro-Ecosystem Services, The
University ofTokyo, Nishitokyo, Japan
2 School ofIntegrative Plant Science, Cornell University,
Ithaca, NY, USA
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... When the RZT is low or high, plants activate antioxidant reactions (Li et al., 2019). Also, the optimal RZT varies with air temperature (Yamori et al., 2022). Root growth increases linearly from minimum to optimum temperature with increasing temperature, but further increases in RZT are accompanied by a rapid decrease in root Downloaded from https://academic.oup.com/aob/advance-article/doi/10.1093/aob/mcad127/7265388 by guest on 10 September 2023 A c c e p t e d M a n u s c r i p t 4 and shoot growth (Arkin & Taylor, 1981;Miller, 1986;Yamori et al., 2022). ...
... Also, the optimal RZT varies with air temperature (Yamori et al., 2022). Root growth increases linearly from minimum to optimum temperature with increasing temperature, but further increases in RZT are accompanied by a rapid decrease in root Downloaded from https://academic.oup.com/aob/advance-article/doi/10.1093/aob/mcad127/7265388 by guest on 10 September 2023 A c c e p t e d M a n u s c r i p t 4 and shoot growth (Arkin & Taylor, 1981;Miller, 1986;Yamori et al., 2022). Other studies even suggest that RZT appears more critical than air temperature in controlling plant growth (Aldous & Kaufmann, 1979;Kuroyanagi & Paulsen, 1988;Paulsen, 1994;Xu et al., 2001). ...
... Separate control over the RZT and air temperature affect CEA operations from a plant physiological viewpoint since previous studies have suggested that RZT applied to various species have strong influences on plant growth and that RZT and air temperature can create different physiological responses (Ruter & Ingram, 1992;McMichael & Burke, 1994;Udomprasert et al., 1995;Ziska & Bunce, 1998;Sattelmacher et al., 1990;Pardales et al., 1991;Xu et al., 2001;Yamori et al., 2022). Resource-useefficiency is critical in CEA because the yield benefits need to justify the increased production environment costs due to the increased costs of food production relative to conventional outdoor field agriculture (Lubna et al., 2022). ...
Controlling Root Zone Temperature Improves Plant Growth and Pigments in Hydroponic Lettuce
Article
Full-text available
  • Sep 2023
  • ANN BOT-LONDON
Background and aims: Air and root zone temperatures are important environmental factors affecting plant growth and yield. Numerous studies have demonstrated that air temperature strongly affects plant growth and development. Despite the extensive literature on air temperature, comprehensive studies on the effects of root zone temperature (RZT) on plant growth, elemental composition, and pigments are still limited. This study carefully observed the effects of RZT in red leaf lettuce to understand its effect on lettuce growth and pigment content. Methods: Lettuce (Lactuca sativa, cv. red-leaf 'Red Fire') were hydroponically grown in a plant factory with artificial light under 3 RZT treatments (15, 25, and 35 °C) for 13 days. The present study investigated the comprehensive effects that RZT had on the production of red leaf lettuce by metabolome and ionome analyses. Key results: The 25°C RZT treatment achieved maximum shoot and root dry weight. The 35°C RZT decreased plant growth but significantly increased pigment contents (e.g., anthocyanins, carotenoids). In addition, the RZT heating treatment during plant cultivation, which changed from 25°C RZT to 35°C RZT for 8 days before harvest, significantly increased shoot dry weight compared to the 35°C RZT, and significantly increased pigments compared to the 25°C RZT. The 15°C RZT resulted in significantly less pigment contents relative to the 35 °C RZT. The 15°C RZT also resulted in shoot and root dry weights greater than the 35°C RZT but less than the 25 °C RZT. Conclusions: The present study demonstrated that plant growth and pigments can be enhanced by adjusting RZT during different stages of plant growth to attain enhanced pigment contents while minimizing yield loss. The end result from this study suggests that controlling RZT could be a viable method to improve lettuce quality via pigment content quality enhancement while maintaining acceptable yields.
View
... This study focused on the effects of LT, WL and LT WL stress on the root system of snapdragon. Under the three kinds of stress, the root parameters of snapdragon were inhibited, and the plant root status could indicate the degree of stress, because LT limited the elongation and differentiation of root cells (Nagasuga et al., 2011;Zhu et al., 2015;Yamori et al., 2022), thereby reducing the biomass of roots. Similarly, WL stress decreased the perennial ryegrass root length, root surface area, root mass, and the root shoot ratios (Fu et al., 2020), which was basically consistent with the results of our study. ...
Arbuscular mycorrhizal fungi enhanced resistance to low-temperature weak-light stress in snapdragon (Antirrhinum majus L.) through physiological and transcriptomic responses
Article
Full-text available
  • Apr 2024
Introduction Low temperature (LT) and weak light (WL) seriously affects the yield and quality of snapdragon in winter greenhouse. Arbuscular mycorrhizal fungi (AMF) exert positive role in regulating growth and enhancing abiotic stress tolerance in plants. Nevertheless, the molecular mechanisms by AMF improve the LT combined with WL (LTWL) tolerance in snapdragon remain mostly unknown. Methods We compared the differences in root configuration, osmoregulatory substances, enzymatic and non-enzymatic antioxidant enzyme defense systems and transcriptome between AMF-inoculated and control groups under LT, WL, low light, and LTWL conditions. Results Our analysis showed that inoculation with AMF effectively alleviated the inhibition caused by LTWL stress on snapdragon root development, and significantly enhanced the contents of soluble sugars, soluble proteins, proline, thereby maintaining the osmotic adjustment of snapdragon. In addition, AMF alleviated reactive oxygen species damage by elevating the contents of AsA, and GSH, and the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR), and glutathione reductase (GR). RNA-seq analysis revealed that AMF regulated the expression of genes related to photosynthesis (photosystem I related proteins, photosystem II related proteins, chlorophyll a/b binding protein), active oxygen metabolism (POD, Fe-SOD, and iron/ascorbate family oxidoreductase), plant hormone synthesis (ARF5 and ARF16) and stress-related transcription factors gene (bHLH112, WRKY72, MYB86, WRKY53, WRKY6, and WRKY26) under LTWL stress. Discussion We concluded that mycorrhizal snapdragon promotes root development and LTWL tolerance by accumulation of osmoregulatory substances, activation of enzymatic and non-enzymatic antioxidant defense systems, and induction expression of transcription factor genes and auxin synthesis related genes. This study provides a theoretical basis for AMF in promoting the production of greenhouse plants in winter.
View
... Follow-up research should examine the temperature field and water spatial distribution characteristics of the root zone under warm-water irrigation for different cultivation modes, such as soil, substrate, and coconut bran cultivation, and establish the corresponding mathematical models. In addition, we also need to study optimal control strategies for root zone temperature and air temperature to provide a more suitable growth environment for plants, reduce the impact of low temperature stress on plant growth, and promote increased yields and income [39]. ...
Optimized Design of Irrigation Water-Heating System and Its Effect on Lettuce Cultivation in a Chinese Solar Greenhouse
Article
Full-text available
  • Mar 2024
In cold regions, the low irrigation water temperature is an important factor of low-temperature stress for greenhouse crops. In this paper, an irrigation water-heating system (IWHS) is proposed to increase the water temperature by utilizing the excess heat in the solar greenhouse. The heat-collection capacity of the system was analyzed by screening the IWHS process parameters in a Chinese solar greenhouse, and a warm-water irrigation experiment for lettuce was conducted. The results demonstrated that the water temperature increased with the increase in wind speed, and the increase in daily average water temperature reached the maximum value of 8.6 °C at 4.5 m/s wind speed. When the heat exchanger was installed at a height of 3.0 m, the collector capacity increased by 17.8% and 6.0% compared with the heating capacity at 0 m and 1.5 m, respectively, and the operation termination water temperature was 22.0–32.2 °C and its coefficient of performance (COP) was optimal. Surface darkening of the heat exchanger did not affect the heat-collection capacity of the system. Using the IWHS effectively improved the temperature of lettuce irrigation water in the Chinese solar greenhouse. The increased frequency of warm-water irrigation significantly promoted lettuce growth and increased the average yield per plant by 15.9%. Therefore, IWHS effectively increased the irrigation water temperature in a Chinese solar greenhouse in winter. Improving the system would enhance its economic and application value.
View
... For example, seasonal temperature changes expose plants to varying temperatures. As a result, the growth, development, and reproduction of plants will be significantly impacted by temperature variations in a few days of the month [3][4][5]. The degree to which plants acclimate to temperature is expected to have a significant impact on the future soil-plant-atmosphere carbon cycle. ...
A Bibliometric Analysis Unveils Valuable Insights into the Past, Present, and Future Dynamics of Plant Acclimation to Temperature
Article
Full-text available
  • Feb 2024
Plant temperature acclimation is closely related to maintaining a positive carbon gain under future climate change. However, no systematic summary of the field has been conducted. Based on this, we analyzed data on plant temperature acclimation from the Web of Science Core Collection database using bibliometric software R, RStudio and VOSviewer. Our study demonstrated that a stabilized upward trajectory was noted in publications (298 papers) from 1986 to 2011, followed by a swift growth (373 papers) from 2012 to 2022. The most impactful journals were Plant Cell and Environment, boasting the greatest count of worldwide citations and articles, the highest H-index and G-index, followed by Global Change Biology and New Phytologist, and Frontiers in Plant Science which had the highest M-index. The USA and China were identified as the most influential countries, while Atkin was the most influential author, and the Chinese Academy of Sciences was the most influential research institution. The most cited articles were published in the Annual Review of Plant Biology in 1999. “Cold acclimation” was the most prominent keyword. Future plant temperature acclimation research is expected to focus on thermal acclimation and photosynthesis, which have important significance for future agricultural production, forestry carbon sequestration, and global food security. In general, this study provides a systematic insight of the advancement, trend, and future of plant temperature acclimation research, enhancing the comprehension of how plants will deal with forthcoming climate change.
View
... Lettuce growth will be optimal in the air temperature range of 25°C to 28°C and humidity ranging from 60% to 78%. Unstable temperature and humidity conditions may cause the plants to wilt and interfere with the development of seedlings [3] [4]. In order for lettuce plants to germinate properly, soil humidity needs to be maintained at a value of 60% [5]. ...
Soil Moisture Control System for Lettuce Seeds: Time-based Alternative Approach
Article
Full-text available
  • Jun 2023
The utilization of lettuce leaves as a nutritious dish has made its demand relatively high. This research presents a moisture control method to optimize seed growth for lettuce. The prototype system has been developed using Arduino Mega, DF Robot soil moisture humidity sensor, and DC spraying pump for testing three different control scenarios, the open loop control system (time-based), the Proportional control system, and the combination of open loop and Proportional control method as an alternative. The results show that each control method can achieved the desired moisture of rockwool at 60%. Also, the combination of open loop and Proportional control can lessen energy usage of the system by up to 51% compared to the common open loop method.
View
... Thermal fluctuations, depending on the stage of development and the duration of exposure, can significantly affect the healthy growth of the roots and implicitly the root-shoot relationship [30,31]. Researchers have found that by optimizing the root zone temperature, plant growers could increase their plant production [32]. ...
Sedum Growth Patterns under Different Pedoclimatic Conditions
Article
Full-text available
  • Jul 2023
Citation: Cotoz, A.-P.; Dan, V.-S.; Gocan, T.-M.; Andreica, I.; Rózsa, S.; Cantor, M. Sedum Growth Patterns under Different Pedoclimatic Conditions. Plants 2023, 12, 2739. Abstract: This research paper presents a case study analysis of the behavior of three Sedum varieties and their growth in three different types of substrates without additional watering or fertilizing. The study aims to identify a suitable substrate for propagation and to provide insight into the plant's growth patterns. By analyzing the growth of the Sedum species and varieties-SS'PW', SS'CB', and SS'P'-without intervening in their growth process, we were able to identify factors that play a more crucial role in promoting root growth, plant growth, aesthetic value, and use. Over a 20-month period, various technical tools were employed to conduct observations and measurements for both plants and weather conditions. The type of substrate significantly affected plant growth, with the green roof substrate exhibiting the highest overall average monthly root growth rate (0.92 ± 0.05 d, 1.01 ± 0.05 b, 0.96 ± 0.05 c) while in the case of stem growth, among all three varieties, the best results were obtained in the commercial mix (0.87 ± 0.04 a, 0.40 ± 0.02 c, 0.35 ± 0.02 d). Based on the morphological analyses, all values were significantly lower than the control. Best results for leaf weight and surface area were noticed in the green roof substrate with an average growth of 46%, 53%, 55%, and for stem weight, length, and thickness in the commercial mix with 64%, 61%, and 55% compared to the control, respectively. Leaves had varying morphological characteristics, but the chromatic characteristics were preserved. The plants had an overall poor growth which may not be desirable in landscape designs. The findings of this study are applicable in the planning and execution of eco-friendly infrastructure initiatives, leading to the development of more robust and environmentally friendly urban settings.
View
Raising root zone temperature improves plant productivity and metabolites in hydroponic lettuce production
Article
Full-text available
  • Apr 2024
While it is commonly understood that air temperature can greatly affect the process of photosynthesis and the growth of higher plants, the impact of root zone temperature (RZT) on plant growth, metabolism, essential elements, as well as key metabolites like chlorophyll and carotenoids, remains an area that necessitates extensive research. Therefore, this study aimed to investigate the impact of raising the RZT on the growth, metabolites, elements, and proteins of red leaf lettuce. Lettuce was hydroponically grown in a plant factory with artificial light at four different air temperatures (17, 22, 27, and 30°C) and two treatments with different RZTs. The RZT was raised 3°C above the air temperature in one group, while it was not in the other group. Increasing the RZT 3°C above the air temperature improved plant growth and metabolites, including carotenoids, ascorbic acids, and chlorophyll, in all four air temperature treatments. Moreover, raising the RZT increased Mg, K, Fe, Cu, Se, Rb, amino acids, and total soluble proteins in the leaf tissue at all four air temperatures. These results showed that raising the RZT by 3°C improved plant productivity and the metabolites of the hydroponic lettuce by enhancing nutrient uptake and activating the metabolism in the roots at all four air temperatures. Overall, this research demonstrates that plant growth and metabolites can be improved simultaneously with an increased RZT relative to air temperature. This study serves as a foundation for future research on optimizing RZT in relation to air temperature. Further recommended studies include investigating the differential effects of multiple RZT variations relative to air temperature for increased optimization, examining the effects of RZT during nighttime versus daytime, and exploring the impact of stem heating. This research has the potential to make a valuable contribution to the ongoing growth and progress of the plant factory industry and fundamental advancements in root zone physiology. Overall, this research demonstrates that plant growth and metabolites can be improved simultaneously with an increased RZT relative to air temperature. This study serves as a foundation for future research on optimizing RZT in relation to air temperature. Further recommended studies include investigating the differential effects of multiple RZT variations relative to air temperature for increased optimization, examining the effects of RZT during nighttime versus daytime, and exploring the impact of stem heating. This research has the potential to make a valuable contribution to the ongoing growth and progress of the plant factory industry and fundamental advancements in root zone physiology.
View
Enhancing Productivity and Improving Nutritional Quality of Subtropical and Temperate Leafy Vegetables in Tropical Greenhouses and Indoor Farming Systems
Article
Full-text available
  • Mar 2024
The total land used for land-based food farms is less than 1% in Singapore. As a result, more than 90% of Singapore’s food needs are imported. To strengthen food security, Singapore has set a target to develop the capability and capacity of the agri-food industry to locally produce 30% of its nutritional needs by 2030. To achieve this goal, technology is the key to helping farms to “grow more with less”. This review first discusses how aeroponic systems have been adapted for growing all kinds of leafy vegetables in the tropics through the manipulation of root-zone temperature and heat priming to save power energy. Growing vegetable crops indoors and in greenhouses not only allows the growers to achieve high productivity but also enables them to enhance nutritional values. The second part of this paper emphasizes how to achieve substantial yield through deficit irrigation with higher nutritional quality in a cost-effective manner. Growing crops vertically has become increasingly popular, as it increases land use. We establish a commercially viable LED-integrated aeroponic system to grow vegetables vertically. The last part of the paper discusses the impacts of LED spectral quality, quantity, and duration on vegetable production.
View
View
Assessment of the Potential to Use the Expelled Heat Energy from a Typical Data Centre in Ireland for Alternative Farming Methods
Article
  • Sep 2023
Citation: Borland, P.L.; McDonnell, K.; Harty, M. Assessment of the Potential to Use the Expelled Heat Energy from a Typical Data Centre in Ireland for Alternative Farming Methods. Energies 2023, 16, 6704. Abstract: Data centres, though a necessary part of modern society, are being stigmatised for consuming vast amounts of electricity for their operational and cooling needs. Due to Ireland's reliance on fossil fuels to meet the increased energy demand of data centres, the data centres are contributing significantly to Ireland's total carbon emissions. As much of this energy is expelled from data centres as waste heat energy, the potential for recycling some of this wasted heat energy was explored using environmentally friendly systems from recent publications. The recovered waste heat energy was applied in a vertical farming system, and the benefits of this waste heat to the vertical farm were analysed and quantified in two scenarios. Using conservative estimates, it was predicted that each vertical farm could be between 5-23% the size of the data centre and produce enough food to feed between 14-61 adults their daily calorie needs, and between 13-58 people their daily fresh produce requirements, depending on the scenario applied. For a more accurate prediction, each vertical farm would have to be assessed on a case-by-case basis, as there is no current research in this area. However, there was not enough data available on Irish data centres to perform these calculations.
View
High Light Intensity Applied Shortly Before Harvest Improves Lettuce Nutritional Quality and Extends the Shelf Life
Article
Full-text available
  • Jan 2021
The effect of light intensity applied shortly before harvest on the nutritional quality, postharvest performance, and shelf life of loose-leaf lettuce (Lactuca sativa L. cv. Expertise RZ Salanova®) was investigated. Lettuce was grown either in a greenhouse with supplemental high-pressure sodium light (Experiment 1, EXP 1) or in a climate room under white LED light (Experiment 2, EXP 2). In both experiments full grown plants were transferred to a climate room for the End of Production (EoP) light treatments during the last week of cultivation. During EoP lighting plants were exposed to different intensities (0, 110, and 270 μmol m–2 s–1 in EXP 1; 50, 210, and 470 μmol m–2 s–1 in EXP 2) from white-red LEDs for 6 (EXP 2) or 7 days (EXP 1). Mature leaves were then harvested and stored in darkness at 10°C to study the postharvest performance. Changes in dry matter content, total ascorbic acid, and carbohydrates (including glucose, fructose sucrose, and starch) levels were determined during EoP lighting and during the subsequent shelf life as indicators of lettuce nutritional quality. Quality aspects (appearance, texture, and odor) were accessed during the shelf life as indicators of postharvest performance. In both experiments, high light intensities applied in EoP lighting increased dry matter percentage and contents of ascorbic acid (AsA) and carbohydrates at harvest and these increased levels were maintained during the shelf life. Increased light intensity in EoP treatment also extended the shelf life. The levels of AsA and carbohydrates at harvest correlated positively with the subsequent shelf life, indicating that the prolonged shelf life relies on the improved energy and antioxidant status of the crop at harvest.
View
View
Root Systems in Relation to Stress Tolerance
Article
Full-text available
  • Aug 1986
Roots anchor the plant in the soil, absorb and translocate water and nutrients, synthesize and transport growth regulators and other organic compounds, provide a sink for carbohydrates from the shoots, and in some species act as storage organs. Most research on roots has dealt with their role in absorption. Root characteristics that affect the area of absorbing surface are important, i.e., root length density, number and type of root hairs, and mycorrhizal relations. With nutrients that diffuse slowly in the soil, such as P and K, root density is especially important. Factors that reduce root growth may injure the plant by reducing the volume and intensity of soil exploration. Fortunately, plants produce more roots than are needed for normal growth–insurance that the plant can survive stresses, purchased at a cost of the increased photosynthate and other materials required for the extra root production.
View
Interactions between Air and Root Temperatures on Greenhouse Tomato: I. Growth, Development, and Yield
Article
Full-text available
  • Nov 1983
Greenhouse tomato plants ( Lycopersicon esculentum Mill. cv. Vendor) were grown at 5 root temperatures (12°, 18°, 24°, 30°, and 36°C) and 4 night air temperatures (12°, 15°, 18°, and 21°) for 3 months. Low root and low night air temperatures contributed to high root dry weight. However, under warm soil temperature conditions (30° and 36°), roots were most efficient in sustaining shoot growth and in absorbing water as indicated by the percentage of shoot dry weight. Shoot growth was maximum at 15° night air temperature and 30° root temperature. High root temperatures are required at low night air temperature for maximum shoot growth. Maximum yields were obtained at a combination of 18° night air temperature and 24° root temperature. An increase in soil temperature partly offsets the detrimental effects of low night air temperatures.
View
Overexpression of both Rubisco and Rubisco activase rescues rice photosynthesis and biomass under heat stress
Article
  • Mar 2021
Global warming threatens food security by decreasing crop yields through damage to photosynthetic systems, especially Rubisco activation. We examined whether co‐overexpression of Rubisco and Rubisco activase improves the photosynthetic and growth performance of rice under high temperatures. We grew three rice lines—the wild‐type (WT), a Rubisco activase–overexpressing line (oxRCA), and a Rubisco‐ and Rubisco activase–co‐overexpressing line (oxRCA‐RBCS)—and analyzed photosynthesis and biomass at 25 and 40°C. Compared with the WT, the Rubisco activase content was 153% higher in oxRCA and 138% higher in oxRCA‐RBCS, and the Rubisco content was 27% lower in oxRCA and similar in oxRCA‐RBCS. The CO2 assimilation rate (A) of WT was lower at 40°C than at 25°C, attributable to Rubisco deactivation by heat. On the other hand, that of oxRCA and oxRCA‐RBCS was maintained at 40°C, resulting in higher A than WT. Notably, the dry weight of oxRCA‐RBCS was 26% higher than that of WT at 40°C. These results show that increasing the Rubisco activase content without the reduction of Rubisco content could improve yield and sustainability in rice at high temperature. This article is protected by copyright. All rights reserved.
View
View
View
Plant Factory: An Indoor Vertical Farming System for Efficient Quality Food Production
Book
  • Oct 2015
Plant Factory: An Indoor Vertical Farming System for Efficient Quality Food Production provides information on a field that is helping to offset the threats that unusual weather and shortages of land and natural resources bring to the food supply. As alternative options are needed to ensure adequate and efficient production of food, this book represents the only available resource to take a practical approach to the planning, design, and implementation of plant factory (PF) practices to yield food crops. The PF systems described in this book are based on a plant production system with artificial (electric) lights and include case studies providing lessons learned and best practices from both industrial and crop specific programs. With insights into the economics as well as the science of PF programs, this book is ideal for those in academic as well as industrial settings. Provides full-scope insight on plant farm, from economics and planning to life-cycle assessment. Presents state-of-the-art plant farm science, written by global leaders in plant farm advancements. Includes case-study examples to provide real-world insights.
View
Role of the Plant Factory With Artificial Lighting (PFAL) in Urban Areas
Chapter
  • Dec 2016
The increasing importance of fresh food production in urban areas is discussed and the methods for achieving efficient production are described. Firstly, resource inflow and waste outflow in urban areas are described. Then, the possibility of significantly reducing the outflow waste by using a large portion of it as an essential resource for growing plants in urban ecosystems is discussed. Secondly, the role of the plant factory with artificial lighting (PFAL) is discussed, and the plants that are suited and unsuited to PFALs are described. Finally, criticisms of PFALs are analyzed, and the methodology toward a sustainable PFAL is discussed.
View
Physiology and determination of crop yield
Article
  • Jan 1994
This volume is based on an international symposium which was cosponsored by the ASA, CSSA, and the SSA and held at the University of Florida in June 1991. After two introductory chapters the volume is divided into four sections. Firstly, growth and development is covered including: seed germination and seedling establishment; root growth and activity/nutrient uptake; leaf and shoot growth; seed growth and development and intrinsic factors regulating it; crop ontogeny and development; and ontogenetic and morphological plasticity in crop plants. Next various aspects of metabolism are examined. The third section looks at the effects of environmental stresses: drought; high temperature responses; cold hardiness; low temperature and its affect on crop yield; carbon dioxide increase; air pollutants; and ultraviolet radiation and ozone depletion. The last section contains three review papers: limits to crop yields?; modelling genetic yield potential; and plant breeding opportunities. -S.R.Harris
View