scholarly journals Canopy Size and Light Use Efficiency Explain Growth Differences between Lettuce and Mizuna in Vertical Farms

Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 704
Author(s):  
Theekshana C. Jayalath ◽  
Marc W. van Iersel
Keyword(s):  
Energy Use ◽  
Incident Light ◽  
Dry Weight ◽  
Biomass Energy ◽  
Photon Flux ◽  
Light Use Efficiency ◽  
Growing Period ◽  
Use Efficiency ◽  
High Yields ◽  
Canopy Size

Vertical farming is increasingly popular due to high yields obtained from a small land area. However, the energy cost associated with lighting of vertical farms is high. To reduce this cost, more energy efficient (biomass/energy use) crops are required. To understand how efficiently crops use light energy to produce biomass, we determined the morphological and physiological differences between mizuna (Brassica rapa var. japonica) and lettuce (Lactuca sativa ‘Green Salad Bowl’). To do so, we measured the projected canopy size (PCS, a morphological measure) of the plants throughout the growing cycle to determine the total amount of incident light the plants received. Total incident light was used together with the final dry weight to calculate the light use efficiency (LUE, g of dry weight/mol of incident light), a physiological measure. Plants were grown under six photosynthetic photon flux densities (PPFD), from 50 to 425 µmol m–2 s–1, for 16 h d–1. Mizuna and lettuce were harvested 27 and 28 days after seeding, respectively. Mizuna had greater dry weight than lettuce (P < 0.0001), especially at higher PPFDs (PPFD ≥ 125 µmol m–2 s–1), partly because of differences in the projected canopy size (PCS). Mizuna had greater PCS than lettuce at PPFDs ≥ 125 µmol m–2 s–1 and therefore, the total incident light over the growing period was also greater. Mizuna also had a higher LUE than lettuce at all six PPFDs. This difference in LUE was associated with higher chlorophyll content index and higher quantum yield of photosystem II in mizuna. The combined effects of these two factors resulted in higher photosynthetic rates in mizuna than in lettuce (P = 0.01). In conclusion, the faster growth of mizuna is the result of both a larger PCS and higher LUE compared to lettuce. Understanding the basic determinants of crop growth is important when screening for rapidly growing crops and increasing the efficiency of vertical farms.

scholarly journals Potential Use of a 24-Hour Photoperiod (Continuous Light) with Alternating Air Temperature for Production of Tomato Plug Transplants in a Closed System

HortScience ◽  
2005 ◽  
Vol 40 (2) ◽  
pp. 374-377 ◽  
Author(s):  
Katsumi Ohyama ◽  
Koji Manabe ◽  
Yoshitaka Omura ◽  
Toyoki Kozai ◽  
Chieri Kubota
Keyword(s):  
Air Temperature ◽  
Closed System ◽  
Energy Use ◽  
Electric Energy ◽  
Continuous Light ◽  
Dry Weight ◽  
Photon Flux ◽  
Air Temperatures ◽  
Use Efficiency ◽  
Potential Use

To evaluate the potential use of a 24-hour photoperiod for transplant production in a closed system, tomato (Lycopersicon esculentum Mill.) plug transplants were grown for 17 days either under a 24-hour photoperiod with a photosynthetic photon flux (PPF) of 200 μmol·m-2·s-1 or under a 16-hour photoperiod with a PPF of 300 μmol·m-2·s-1, resulting in the same daily integrated PPF (17.3 mol·m-2). Air temperatures were alternated between 28 °C during the first 16 hours and 16 °C for the subsequent 8 hours of each day. Fresh weight, dry weight and leaf area were 41%, 25%, and 64% greater, respectively, under the 24-hour photoperiod than under the 16-hour photoperiod. Physiological disorders (e.g., chlorosis and/or necrosis) were not observed under the 24-hour photoperiod, probably due to the alternating air temperature. Floral development of plants originating from both treatments did not differ significantly. Electric energy use efficiency of the closed system was 9% greater under the 24-hour photoperiod than under the 16-hour photoperiod. These results suggest that using a 24-hour photoperiod with relatively low PPF can reduce both initial and operational costs for transplant production in a closed system due to the reduction in the number of lamps.

scholarly journals Adding Far-Red to Red-Blue Light-Emitting Diode Light Promotes Yield of Lettuce at Different Planting Densities

2021 ◽  
Vol 11 ◽  
Author(s):  
Wenqing Jin ◽  
Jorge Leigh Urbina ◽  
Ep Heuvelink ◽  
Leo F. M. Marcelis
Keyword(s):  
Leaf Area ◽  
Biomass Production ◽  
Plant Biomass ◽  
Stem Elongation ◽  
Incident Light ◽  
Dry Weight ◽  
Light Interception ◽  
Planting Density ◽  
Light Use Efficiency ◽  
Use Efficiency

The economic viability and energy use of vertical farms strongly depend on the efficiency of the use of light. Increasing far-red radiation (FR, 700–800 nm) relative to photosynthetically active radiation (PAR, 400–700 nm) may induce shade avoidance responses including stem elongation and leaf expansion, which would benefit light interception, and FR might even be photosynthetically active when used in combination with PAR. The aims of this study are to investigate the interaction between FR and planting density and to quantify the underlying components of the FR effects on growth. Lettuce (Lactuca sativa cv. Expertise RZ) was grown in a climate chamber under two FR treatments (0 or 52 μmol m–2 s–1) and three planting densities (23, 37, and 51 plants m–2). PAR of 89% red and 11% blue was kept at 218 μmol m–2 s–1. Adding FR increased plant dry weight after 4 weeks by 46–77% (largest effect at lowest planting density) and leaf area by 58–75% (largest effect at middle planting density). Radiation use efficiency (RUE: plant dry weight per unit of incident radiation, 400–800 nm) increased by 17–42% and incident light use efficiency (LUEinc: plant dry weight per unit of incident PAR, 400–700 nm) increased by 46–77% by adding FR; the largest FR effects were observed at the lowest planting density. Intercepted light use efficiency (LUEint: plant dry weight per unit of intercepted PAR) increased by adding FR (8–23%). Neither specific leaf area nor net leaf photosynthetic rate was influenced by FR. We conclude that supplemental FR increased plant biomass production mainly by faster leaf area expansion, which increased light interception. The effects of FR on plant dry weight are stronger at low than at high planting density. Additionally, an increased LUEint may contribute to the increased biomass production.

Biogeographical Patterns of Light Use efficiency?

2021 ◽  
Author(s):  
David Sandoval ◽  
Iain Colin Prentice
Keyword(s):  
Maximum Rate ◽  
Spatial Organization ◽  
Gross Primary Production ◽  
Incident Light ◽  
Direct Consequence ◽  
Theoretical Explanation ◽  
Light Use Efficiency ◽  
Mountain Regions ◽  
Use Efficiency ◽  
Photosynthetic Traits

&lt;p&gt;The emergent spatial organization of ecosystems in elevational gradients suggest that some ecosystem processes, important enough to shape morphological traits, must show similar patterns.&lt;/p&gt;&lt;p&gt;The most important of these processes, gross primary production (GPP), usually (albeit with some exceptions) decreases with elevation. This was previously thought to be a direct consequence either of the decrease in temperature, or the decrease of incident light due to cloud cover. However, some recent developments in photosynthetic theory, plus the unprecedented availability of ecophysiological data, support the hypothesis that plants acclimate (optimize) their photosynthetic traits to the environment. In this new theoretical context, the temperature is no longer considered as a major constraining factor, except when either freezing or excessively high temperatures inhibit plant function generally.&lt;/p&gt;&lt;p&gt;Two of the most important photosynthetic traits, the maximum rate of carboxylation (V&lt;sub&gt;CMAX&lt;/sub&gt;) and the intrinsic quantum efficiency (&amp;#966;&lt;sub&gt;o&lt;/sub&gt;), vary in opposite directions with increasing elevation. Plants tend to increase V&lt;sub&gt;CMAX&lt;/sub&gt; to compensate for a decrease in the ratio leaf-internal to ambient partial pressures of CO&lt;sub&gt;2&lt;/sub&gt;, while &amp;#966;&lt;sub&gt;o&lt;/sub&gt; increases with temperature up to a plateau. To explore how these different responses, documented at leaf level, converge in emergent spatial patterns at ecosystem scale we considered how elevation shape light use efficiency (defined as the ratio of CO&lt;sub&gt;2&lt;/sub&gt; assimilated over light absorbed) over mountain regions worldwide. We used data from eddy-covariance flux towers, from different networks, located in mountain regions around the world, adding up to 618 station-years of record. To complement our analysis, we included theoretical predictions using an optimality model (P-model) and evaluated changes in the spatial pattern with simulation experiments.&lt;/p&gt;&lt;p&gt;Empirically we found an asymptotic response of LUE to the average daytime temperature during the growing season with increasing elevation, and a small, but globally consistent effect of elevation on LUE. We propose a theoretical explanation for the observation that temperature differences have little impact on the biogeographical pattern of LUE, but we also find that different assumptions on the acclimation of the maximum rate of electron transport (J&lt;sub&gt;MAX&lt;/sub&gt;) and &amp;#966;&lt;sub&gt;o&lt;/sub&gt; change this pattern.&lt;/p&gt;

scholarly journals The effect of timing of shade on development, dry matter production and light-use efficiency in groundnut (Arachis hypogaea L.) under field conditions

1990 ◽  
Vol 41 (4) ◽  
pp. 633 ◽  
Author(s):  
CM Stirling ◽  
JH Williams ◽  
CR Black ◽  
CK Ong
Keyword(s):  
Arachis Hypogaea ◽  
Dry Matter ◽  
Incident Light ◽  
Light Use Efficiency ◽  
Matter Production ◽  
Arachis Hypogaea L ◽  
Leaf Area Expansion ◽  
Use Efficiency ◽  
Area Expansion ◽  
Final Harvest

During the rainy season in India, bamboo screens intercepting approximately 46% of the incident light were used to simulate the effect of shading by a cereal grown as an intercrop with groundnut (Arachis hypogaea L.). The treatments comprised an unshaded control and two durations of shading extending from peg initiation (T1) and the onset of pod filling (T2) to final harvest. Plant height was greatest in the T1 crop, but the maximum rates of leaf development on the main stem, leaf area expansion and pod production were similar in all crops. Shading appeared to reduce the rate of the linear growth phase because the reduced light interception was not entirely offset by an increase in light-use efficiency. Premature senescence in the shaded crops coincided with the virtual cessation of pod production, although continued allocation of dry matter to reproductive structures in the T1 crop resulted in a greater proportion of pods being filled at final harvest than in the other treatments. The responses of groundnut to timing of shade are discussed in terms of their implications for the selection of improved crop combinations for intercropping.

scholarly journals Growth and Energy Use Efficiency of Grafted Tomato Transplants as Affected by LED Light Quality and Photon Flux Density

Agriculture ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 816
Author(s):  
Jianfeng Zheng ◽  
Peidian Gan ◽  
Fang Ji ◽  
Dongxian He ◽  
Po Yang
Keyword(s):  
Energy Use ◽  
Light Quality ◽  
Red Light ◽  
Electrical Energy ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Red Led ◽  
Use Efficiency ◽  
Led Lights

This study was conducted to compare the effects of broad spectrum during the whole seedling period and photon flux density (PFD) in the healing stage on the growth and energy use efficiency of grafted tomato (Lycopersicon esculentum Mill.) transplants in a plant factory. Fluorescent lights, white LED lights, and white plus red LED lights were applied at the growth processes of grafted tomato transplants from germination of rootstock and scion to post-grafting. Three levels of PFD (50, 100, 150 μmol m−2 s−1) were set in the healing stage under each kind of light quality. The results indicated that the growth and quality of grafted tomato transplants under different broad spectrums were influenced by the ratio of red to blue light (R/B ratio) and the ratio of red to far-red light (R/FR ratio). A higher R/B ratio was beneficial to total dry matter accumulation, but excessive red light had a negative effect on the root to shoot ratio and the seedling quality index. The higher blue light and R/FR ratio suppressed stem extension synergistically. The LED lights had good abilities to promote plant compactness and leaf thickness in comparison with fluorescent lights. The plant compactness and leaf thickness increased with the increase in daily light integral in the healing stage within a range from 2.5 to 7.5 mol m−2 d−1 (PFD, 50 to 150 μmol m−2 s−1). Compared to fluorescent lights, the LED lights showed more than 110% electrical energy saving for lighting during the whole seedling period. Higher PFD in the healing stage did not significantly increase the consumption of electric power for lighting. White plus red LED lights with an R/B ratio of 1.2 and R/FR ratio of 16 were suggested to replace fluorescent lights for grafted tomato transplants production considering the high quality of transplants and electrical energy saving, and PFD in the healing stage was recommended to be set to 150 μmol m−2 s−1.

Effect of temporally heterogeneous light on photosynthetic light use efficiency, plant acclimation and growth in Abatia parviflora

2019 ◽  
Vol 46 (7) ◽  
pp. 684 ◽  
Author(s):  
Camilo Rey-Sanchez ◽  
Juan M. Posada
Keyword(s):  
Plant Biomass ◽  
Plant Morphology ◽  
Net Photosynthesis ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Light Use Efficiency ◽  
Plant Acclimation ◽  
Use Efficiency ◽  
Time Courses

Individual leaves have a unique instantaneous photosynthetic photon flux density (PPFD) at which net photosynthetic light use efficiency (ϵL, the ratio between net photosynthesis and PPFD) is maximised (PPFDϵmax). When PPFD is above or below PPFDϵmax, efficiency declines. Thus, we hypothesised that heterogeneous PPFD conditions should increase the amount of time leaves photosynthesise at a PPFD different than PPFDϵmax and result in reduced growth. To date, this prediction has not been rigorously tested. Here, we exposed seedlings of Abatia parviflora Ruiz &amp; Pav to light regimes of equal total daily irradiance but with three different daily time courses of PPFD: constant PPFD (No_H), low heterogeneity (Low_H) and high heterogeneity (High_H). Mean ϵL, leaf daily photosynthesis and plant growth were all significantly higher in No_H and Low_H plants than in High_H plants, supporting our hypothesis. In addition, mean ϵL was positively related to final plant biomass. Unexpectedly, High_H plants had more etiolated stems and more horizontal leaves than No_H and Low_H plants, possibly due to exposure to low PPFD in the morning and afternoon. In conclusion, PPFD heterogeneity had an important effect on average ϵL, photosynthesis and growth, but also on allocation and plant morphology.

scholarly journals Longer Photoperiods with Adaptive Lighting Control Can Improve Growth of Greenhouse-grown ‘Little Gem’ Lettuce (Lactuca sativa)

HortScience ◽  
2020 ◽  
Vol 55 (4) ◽  
pp. 573-580 ◽  
Author(s):  
Geoffrey Weaver ◽  
Marc W. van Iersel
Keyword(s):  
Lactuca Sativa ◽  
Energy Use ◽  
Control Strategies ◽  
Leaf Size ◽  
Dry Weight ◽  
Photon Flux ◽  
Lighting Control ◽  
Content Index ◽  
Supplemental Lighting ◽  
Greenhouse Growers

Supplemental lighting can improve the growth of greenhouse crops, but the electricity required for supplemental lighting can be a significant expense for greenhouse growers. Lighting control strategies that use the dimmability of light-emitting diodes (LEDs) have the potential to decrease this cost. In our experiments, we tested the hypothesis that providing ‘Little Gem’ lettuce (Lactuca sativa) plants with the same daily amount of light, spread out over a longer photoperiod and at lower average photosynthetic photon flux densities (PPFDs), would improve growth because light is used more efficiently to drive photosynthesis at lower PPFDs. We conducted two greenhouse experiments wherein supplemental light was provided to reach a minimum daily light integral (DLI) of 17 mol·m−2·d−1 with a 12, 15, 18, or 21-hour photoperiod using adaptive lighting control of LED lights. As the photoperiod for supplemental lighting was increased and supplemental light was provided at lower average PPFDs, plant dry weight increased. Conversion efficiency, the estimated increase in dry weight per Joule expended on supplemental lighting, increased as the photoperiod was extended from 12 to 21 hours. Leaf size and chlorophyll content index increased with longer photoperiods. The number of plants with symptoms of tipburn, including apical and marginal necrosis, also increased as the photoperiod was extended. These results demonstrate that adaptive lighting control can be used to increase the growth of ‘Little Gem’ lettuce and the energy use efficiency of supplemental lighting by providing supplemental light at relatively low PPFDs.

scholarly journals Growth, Nutritional Quality, and Energy Use Efficiency of Hydroponic Lettuce as Influenced by Daily Light Integrals Exposed to White versus White Plus Red Light-emitting Diodes

HortScience ◽  
2019 ◽  
Vol 54 (10) ◽  
pp. 1737-1744 ◽  
Author(s):  
Zhengnan Yan ◽  
Dongxian He ◽  
Genhua Niu ◽  
Qing Zhou ◽  
Yinghua Qu
Keyword(s):  
Nutritional Quality ◽  
Energy Use ◽  
Light Emitting Diodes ◽  
Red Light ◽  
Dry Weight ◽  
Light Emitting ◽  
Energy Use Efficiency ◽  
White Leds ◽  
Use Efficiency ◽  
Red Leds

Few researchers examined different red light amounts added in white light-emitting diodes (LEDs) with varied daily light integrals (DLIs) for hydroponic lettuce (Lactuca sativa L.). In this study, effects of DLI and LED light quality (LQ) on growth, nutritional quality, and energy use efficiency of hydroponic lettuce were investigated in a plant factory with artificial lighting (PFAL). Hydroponic lettuce plants (cv. Ziwei) were grown for 20 days under 20 combinations of five levels of DLIs at 5.04, 7.56, 10.08, 12.60, and 15.12 mol·m−2·d−1 and four LQs: two kinds of white LEDs with red to blue ratio (R:B ratio) of 0.9 and 1.8, and two white LEDs plus red chips with R:B ratio of 2.7 and 3.6, respectively. Results showed that leaf and root weights and power consumption based on fresh and dry weights increased linearly with increasing DLI, and light and electrical energy use efficiency (LUE and EUE) decreased linearly as DLI increased. However, no statistically significant differences were found in leaf fresh and dry weights and nitrate and vitamin C contents between DLI at 12.60 and 15.12 mol·m−2·d−1. Also, no effects of LQ on leaf dry weight of hydroponic lettuce were observed at a DLI of 5.04 mol·m−2·d−1. White plus red LEDs with an R:B ratio of 2.7 resulted in higher leaf fresh weight than the two white LEDs. LUE increased by more than 20% when red light fraction increased from 24.2% to 48.6%. In summary, white plus red LEDs with an R:B ratio of 2.7 at DLI at 12.60 mol·m−2·d−1 were recommended for commercial hydroponic lettuce (cv. Ziwei) production in PFALs.

scholarly journals CO2 enrichment and increasing light intensity till a threshold level, enhance growth and water use efficiency of lettuce plants in controlled environment

2020 ◽  
Vol 48 (4) ◽  
pp. 2244-2262
Author(s):  
Maryam ESMAILI ◽  
Sasan ALINIAEIFARD ◽  
Mahmoud MASHAL ◽  
Parisa GHORBANZADEH ◽  
Mehdi SEIF ◽  
...  
Keyword(s):  
Light Intensity ◽  
Water Use Efficiency ◽  
Leaf Area ◽  
Water Use ◽  
Dry Weight ◽  
Co2 Concentration ◽  
Photon Flux ◽  
Fresh Weight ◽  
Co2 Concentrations ◽  
Use Efficiency

Carbon dioxide (CO2) and light intensity are the two main environmental drivers known to play important roles in crop growth and yield. In the current study, lettuce seedlings were exposed to four different light intensities [(75, 150, 300 and 600 Photosynthetic Photon Flux Density (PPFD)] and four different concentrations of CO2 (400, 800, 1200 and 1600 ppm). By increasing light intensity and CO2 concentration growth parameters such as fresh weight, dry weight and leaf area were stepwise increased from 75 to 300 PPFD and from 400 ppm to 1200 ppm CO2 concentration. Maximum fresh weight was observed in 300 PPFD under both 1200 ppm and 1600 ppm CO2 concentrations. Highest dry weight was obtained in plants exposed to 300 and 600 PPFD under both 1200 and 1600 ppm CO2 concentrations. Highest leaf area was detected in 300 PPFD under both 1200 and 1600 ppm CO2 concentrations. Widest stomatal pore aperture was detected in 600 PPFD under 400 ppm and 800 ppm CO2 concentrations. Evapotranspiration increased in a light intensity and CO2 concentration-dependent manner; higher light intensity or higher CO2 concentration, more evapotranspiration. Highest water use efficiency (WUE) was achieved in plants exposed to 300 PPFD under 1200 ppm CO2 concentration. In conclusion, to achieve best growth performance and WUE, lettuce should be produced under 300 PPFD light intensity and 1200 ppm CO2.

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