507 Production of Compact Cucumber, Tomato, and Bell Pepper Transplants by Use of Photoselective Plastic Films

Growth chamber experiments were conducted to investigate the effectiveness of several photoselective plastic films in controlling height of `Sweet Success' cucumber, `Mt. Pride' tomato, and `Capistrano' bell pepper transplants. Four types of treatment films; a control, two far-red light intercepting films (YXE-1 and YXE-10), and a red light intercepting film (SXE-1), with R: FR ratios of 1.0, 2.0, 1.6, and 0.8, respectively, were used as the covering materials of experimental chambers. Photosynthetic photon flux (PPF) was adjusted to be the same in all chambers with cheese cloth. Treatment period for cucumber and tomato was 15 days and that for bell pepper was 20 days. At the end of the treatment, significantly shorter plants were found in both YXE-1 and YXE-10 chambers for all the three tested crops. However, YXE-10 was more effective than YXE-1 in producing compact cucumber, tomato and bell pepper transplants. SXE-4 film produced taller plants than control film. Magnitude of response to filtered light varied with the crop species. Number of leaves was not significantly affected by the light transmitted through photoselective filters, indicating that the height reduction was mainly caused by the reduction in internode length. With the commercial development of photoselective greenhouse covers or shade material in the near future, nursery and greenhouse industry could potentially reduce the cost for growth regulating chemicals, reduce the health risks to their workers and consumers, and reduce environmental pollution.

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263 Photoselective Films Influence Flowering of Photoperiodic Species

HortScience ◽

10.21273/hortsci.35.3.436e ◽

2000 ◽

Vol 35 (3) ◽

pp. 436E-436

Author(s):

Teresa A. Cerny ◽

Nihal C. Rajapakse ◽

Ryu Oi

Keyword(s):

Plant Species ◽

Light Quality ◽

Red Light ◽

Photon Flux ◽

Crop Species ◽

Plastic Films ◽

Spectral Filters ◽

Short Day ◽

Long Day ◽

Air Temperatures

Growth chambers constructed from photoselective plastic films were used to investigate the effects of light quality on height manipulation and flowering of photoperiodic plant species. Three types of treatment films were used; control, a far-red light intercepting film (YXE-10) and a red light intercepting film (SXE-4). The red (600-700 nm):far-red (700-800 nm) ratios and phytochrome photoequilibrium estimates for the control, YXE-10 and SXE-4 films were 1.0 and 0.71, 1.5 and 0.77, and 0.71 and 0.67, respectively. The photosynthetic photon flux was adjusted to uniformity among chambers using neutral density filters. Spectral filters did not effect minimum and maximum air temperatures. Experiments were conducted using quantitative long day (Antirrhinum majus and Petunia × hybrida), quantitative short day (Zinnia elegans and Dendranthema × grandiflorum) and day-neutral (Rosa × hydrida) plant species under natural short-day conditions. Plants produced under the YXE-10 filters were significantly shorter than the control plants, while plants produced under the SXE-4 films had similar or increased height compared to the control plants. However, both height response and flowering times varied with the crop species. Flowering time of Rosa × hybrida plants was uniform among all treatments. Flowering of quantitative long-day plants was delayed by at least 10 days under the YXE-10 film and was most responsive to the filtered light. Flowering of quantitative short-day plants was delayed by 2 days under the YXE-10. Days to flower for plants produced under the SXE-4 film were similar to the control plants for all species tested.

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287 Exclusion of End-of-day Far-red Light by Photoselective Plastic Films Reduces Height of Cucumber Seedlings

HortScience ◽

10.21273/hortsci.35.3.441a ◽

2000 ◽

Vol 35 (3) ◽

pp. 441A-441

Author(s):

Shumin Li ◽

Nihal C. Rajapakse ◽

Ryu Oi

Keyword(s):

Red Light ◽

Light Level ◽

Photon Flux ◽

Continuous Exposure ◽

Plastic Films ◽

Cucumber Seedlings ◽

Control Film ◽

Northern Latitudes ◽

Matter Production ◽

Wide Range

The far-red light intercepting photoselective plastic greenhouse covers have been shown to be effective in producing compact vegetable transplants. However, photoselective films reduce the photosynthetic photon flux (PPF) transmission compared to conventional plastic films because of the dye contained in the film. The low PPF in greenhouses covered with photoselective films may result in decreased plant dry matter production and could especially be a problem in the season with low light level and in northern latitudes. Therefore, this study was conducted to determine if covering at the end of the day (EOD) with photoselective films was effective in controlling height of vegetable seedlings. This will allow growers to maintain a high light level during daytime for optimum growth of plants. Cucumber seedlings were exposed to light transmitted through a photoselective film and a clear control film. Three exposure durations: continuous, exposure to filtered light from 3:00 pm to 9:00 am, and from 5:00 pm - 9:00 am, were evaluated. Results show that, after 15 days of treatment, about 25% of height reduction could be achieved by exposing the plants at the EOD from 3:00 pm to 9:00 am or from 5:00 pm to 9:00 am. Plants grown continuously under filtered light were the shortest. Compared to plants grown in photoselective chamber continuously, EOD exposed plants had greater leaf, stem and shoot dry weights, greater leaf area and thicker stem. Specific leaf and stem dry weights were also greater in EOD exposed plants. Number of leaves was not significantly affected by any exposure periods tested. The results suggested that the EOD use of photoselective film is effective in reducing height of cucumber seedlings. The responses of other crops need to be evaluated to test the feasibility of using photoselective film as a EOD cover on wide range of crops.

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Effect of Photoselective Plastic Films on the Growth of Bell Pepper Transplants

HortScience ◽

10.21273/hortsci.33.3.550f ◽

1998 ◽

Vol 33 (3) ◽

pp. 550f-551

Author(s):

Shumin Li ◽

Nihal C. Rajapakse ◽

Roy E. Young ◽

Ryu Oi

Keyword(s):

Plant Height ◽

Copper Sulfate ◽

Liquid Copper ◽

Chlorophyll Concentration ◽

Bell Pepper ◽

Photon Flux ◽

Dry Matter Accumulation ◽

Plastic Films ◽

Height Control ◽

And Control

Removing far-red (FR) light from the greenhouse environment with liquid copper sulfate filters is an effective alternative to application of chemical growth regulators for height control of greenhouse crops. However, liquid filters have limited value in commercial operations because of handling difficulties. In this study, we report the effectiveness of photoselective plastic films that contain a FR intercepting dyestuff in controlling height of `Capistrano' bell pepper seedlings. Four types of treatment films, BCE-L (control), YCE-1 #80L, YCE-1 #75L and YCE-1 #65L, with R:FR ratios of 1.2, 1.7, 2.3 and 3.7, respectively, and one 4% liquid copper sulfate (CuSO4·5H2O) filter with R:FR of 3.5 were used as the covering materials of experimental chambers. Heights of plants grown under YCE-1 #75 or #65 films were ≈30% lower than the control plants. YCE-1 #80 film reduced plant height by ≈15%. Plant height reductions were apparent within 1 to 2 weeks after initiation of the treatments. Plants grown in YCE-1 #75, YCE-1 #65 and CuSO4 chambers had significantly lower total leaf area, leaf size, and leaf and stem dry weights than those grown in the control chamber. No differences were observed between YCE-1 #80 and control plants. No difference was found in the total chlorophyll concentration and the ratio of chlorophyll a to b between the treatment and control plants. Results imply that in peppers, a dyestuff concentration that yields a R:FR over 2 was effective in achieving over 30% height control. Although the filters with R:FR ratios higher than 2 were more effective in controlling height and producing compact pepper plants, the reduction in light intensity, or photosynthetic photon flux (PPF) by increasing dyestuff can reduce dry matter accumulation.

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Does Green Really Mean Go? Increasing the Fraction of Green Photons Promotes Growth of Tomato but Not Lettuce or Cucumber

Plants ◽

10.3390/plants10040637 ◽

2021 ◽

Vol 10 (4) ◽

pp. 637

Author(s):

Paul Kusuma ◽

Boston Swan ◽

Bruce Bugbee

Keyword(s):

Leaf Area ◽

Stem Elongation ◽

Wavelength Region ◽

Sole Source ◽

Dry Mass ◽

Leaf Expansion ◽

Photon Flux ◽

Shade Avoidance ◽

Crop Species ◽

Blue Region

The photon flux in the green wavelength region is relatively enriched in shade and the photon flux in the blue region is selectively filtered. In sole source lighting environments, increasing the fraction of blue typically decreases stem elongation and leaf expansion, and smaller leaves reduce photon capture and yield. Photons in the green region reverse these blue reductions through the photoreceptor cryptochrome in Arabidopsis thaliana, but studies in other species have not consistently shown the benefits of photons in the green region on leaf expansion and growth. Spectral effects can interact with total photon flux. Here, we report the effect of the fraction of photons in the blue (10 to 30%) and green (0 to 50%) regions at photosynthetic photon flux densities of 200 and 500 µmol m−2 s−1 in lettuce, cucumber and tomato. As expected, increasing the fraction of photons in the blue region consistently decreased leaf area and dry mass. By contrast, large changes in the fraction of photons in the green region had minimal effects on leaf area and dry mass in lettuce and cucumber. Photons in the green region were more potent at a lower fraction of photons in the blue region. Photons in the green region increased stem and petiole length in cucumber and tomato, which is a classic shade avoidance response. These results suggest that high-light crop species might respond to the fraction of photons in the green region with either shade tolerance (leaf expansion) or shade avoidance (stem elongation).

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Biofertlizer Lumbrical improves the growth and ex vitro acclimatization of micropropagated pear plants

Silva Balcanica ◽

10.3897/silvabalcanica.22.e57661 ◽

2021 ◽

Vol 22 (1) ◽

pp. 17-30

Author(s):

Nataliya Dimitrova ◽

Lilyana Nacheva ◽

Małgorzata Berova ◽

Danuta Kulpa

Keyword(s):

Woody Species ◽

Photosynthetic Photon Flux Density ◽

Stem Length ◽

Photon Flux ◽

Photon Flux Density ◽

Ex Vitro ◽

Fluorescent Lamps ◽

Planting Material ◽

Number Of Leaves

In vitro micropropagation of plants is highly useful for obtaining large quantities of planting material with valuable economic qualities. However, plantlets grow in vitro in a specific environment and the adaptation after the transfer to ex vitro conditions is difficult. Therefore, the acclimatization is a key step, which mostly determines the success of micropropagation. The aim of this investigation was to study the effect of the biofertlizer Lumbrical on ex vitro acclimatization of micropropagated pear rootstock OHF 333 (Pyrus communis L.). Micropropagated and rooted plantlets were potted in peat and perlite (2:1) mixture with or without Lumbrical. They were grown in a growth chamber at a temperature of 22±2 °C and photoperiod of 16/8 hours supplied by cool-white fluorescent lamps (150 µmol m-2 s-1 Photosynthetic Photon Flux Density, PPFD). The plants were covered with transparent foil to maintain the high humidity, and ten days later, the humidity was gradually decreased. Biometric parameters, anatomic-morphological analyses, net photosynthetic rate and chlorophyll a fluorescence (JIP test) were measured 21 days after transplanting the plants to ex vitro conditions. The obtained results showed that the plants, acclimatized ex vitro in the substrate with Lumbrical, presented better growth (stem length, number of leaves, leaf area and fresh mass) and photosynthetic characteristics as compared to the control plants. This biostimulator could also be used to improve acclimatization in other woody species

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A Plant Process Economic Model for Weed Management Decisions in Irrigated Onion

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.124.1.99 ◽

1999 ◽

Vol 124 (1) ◽

pp. 99-105 ◽

Cited By ~ 4

Author(s):

Claudio M. Dunan ◽

Philip Westra ◽

Frank D. Moore

Keyword(s):

Leaf Area ◽

Plant Density ◽

Light Extinction ◽

Species Number ◽

Yield Reduction ◽

Weed Species ◽

Early Application ◽

Area Index ◽

Variable Approach ◽

Number Of Leaves

A simulation model was built as a decision aid for management of five weed species in direct seeded irrigated onion (Allium cepa L.). The model uses the state variable approach and simulations are driven by temperature and sunlight as photosynthetically active radiation (PAR). It predicts yield reduction caused by competition for PAR according to the ratio of crop leaf area index (LAI) to weed LAI and respective light extinction coefficients (k). Input variables are plant density by species and average number of leaves by species. Number of leaves per plant is used by the model to provide an estimate of initial leaf area per plant. The model calculates initial species LAIs by multiplying species density times average leaf area per plant. The model accurately describes competitive interactions, taking into account respective plant densities, time of emergence, and time of weed removal. It permits economic evaluation of management factors such as handweeding, chemical weed control, herbicide phytotoxicity due to early application, and control of weed flushes during the season. The model is also used to evaluate mechanisms of plant competition for sunlight. In a sensitivity analysis, onion yield loss was more sensitive to weed PAR interception than to PAR use efficiency, the latter a species-dependent constant in the model.

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Photosynthetic Physiology of Blue, Green, and Red Light: Light Intensity Effects and Underlying Mechanisms

Frontiers in Plant Science ◽

10.3389/fpls.2021.619987 ◽

2021 ◽

Vol 12 ◽

Author(s):

Jun Liu ◽

Marc W. van Iersel

Keyword(s):

Blue Light ◽

Interactive Effect ◽

Red Light ◽

Green Light ◽

Photosynthetic Photon Flux Density ◽

Interactive Effects ◽

Photon Flux ◽

Photon Flux Density ◽

Light Spectrum ◽

Response Curves

Red and blue light are traditionally believed to have a higher quantum yield of CO2 assimilation (QY, moles of CO2 assimilated per mole of photons) than green light, because green light is absorbed less efficiently. However, because of its lower absorptance, green light can penetrate deeper and excite chlorophyll deeper in leaves. We hypothesized that, at high photosynthetic photon flux density (PPFD), green light may achieve higher QY and net CO2 assimilation rate (An) than red or blue light, because of its more uniform absorption throughtout leaves. To test the interactive effects of PPFD and light spectrum on photosynthesis, we measured leaf An of “Green Tower” lettuce (Lactuca sativa) under red, blue, and green light, and combinations of those at PPFDs from 30 to 1,300 μmol⋅m–2⋅s–1. The electron transport rates (J) and the maximum Rubisco carboxylation rate (Vc,max) at low (200 μmol⋅m–2⋅s–1) and high PPFD (1,000 μmol⋅m–2⋅s–1) were estimated from photosynthetic CO2 response curves. Both QYm,inc (maximum QY on incident PPFD basis) and J at low PPFD were higher under red light than under blue and green light. Factoring in light absorption, QYm,abs (the maximum QY on absorbed PPFD basis) under green and red light were both higher than under blue light, indicating that the low QYm,inc under green light was due to lower absorptance, while absorbed blue photons were used inherently least efficiently. At high PPFD, the QYinc [gross CO2 assimilation (Ag)/incident PPFD] and J under red and green light were similar, and higher than under blue light, confirming our hypothesis. Vc,max may not limit photosynthesis at a PPFD of 200 μmol m–2 s–1 and was largely unaffected by light spectrum at 1,000 μmol⋅m–2⋅s–1. Ag and J under different spectra were positively correlated, suggesting that the interactive effect between light spectrum and PPFD on photosynthesis was due to effects on J. No interaction between the three colors of light was detected. In summary, at low PPFD, green light had the lowest photosynthetic efficiency because of its low absorptance. Contrary, at high PPFD, QYinc under green light was among the highest, likely resulting from more uniform distribution of green light in leaves.

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Critical Photoperiod and Optimal Quality of Night Interruption Light for Runner Induction in June-Bearing Strawberries

Agronomy ◽

10.3390/agronomy11101996 ◽

2021 ◽

Vol 11 (10) ◽

pp. 1996

Author(s):

Yali Li ◽

Jie Xiao ◽

Jiangtao Hu ◽

Byoung Ryong Jeong

Keyword(s):

Red Light ◽

Photon Flux ◽

Photon Flux Density ◽

Light Emitting ◽

Red Led ◽

Critical Photoperiod ◽

Closed Walk ◽

White Light Emitting Diodes ◽

Optimal Quality

The optimal photoperiod and light quality for runner induction in strawberries ‘Sulhyang’ and ‘Maehyang’ were investigated. Two experiments were carried out in a semi-closed walk-in growth chamber with 25/15 °C day/night temperatures and a light intensity of 250 μmol·m–2·s–1photosynthetic photon flux density (PPFD) provided from white light-emitting diodes (LEDs). In the first experiment, plants were treated with a photoperiod of either 12, 14, 16, 18, 20, or 22 h In the second experiment, a total of 4 h of night interruption (NI) light at an intensity of 70 μmol·m–2·s–1PPFD provided from either red, blue, green, white, or far-red LED in addition to 11 h short day (SD). The results showed that both ‘Sulhyang’ and ‘Maehyang’ produced runners when a photoperiod was longer than 16 h, and the number of runners induced positively correlated with the length of photoperiod. However, the plant growth, contents of chlorophyll, sugar and starch, and Fv/Fo decreased in a 22 h photoperiod. All qualities of the NI light, especially red light, significantly increased the number of runners and daughter plants induced per plant as compared with those in the SD treatment in both cultivars. In a conclusion, a photoperiod between 16 and 20 h and NI light, especially red NI light, can be used for quality runner induction in both ‘Sulhyang’ and ‘Maehyang’.

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The value of red light at night for increasing basil yield

Canadian Journal of Plant Science ◽

10.1139/cjps-2017-0343 ◽

2018 ◽

Vol 98 (6) ◽

pp. 1321-1330

Author(s):

Jaimin S. Patel ◽

Leora Radetsky ◽

Mark S. Rea

Keyword(s):

Plant Height ◽

Red Light ◽

Leaf Size ◽

Cost Effective ◽

Dry Weight ◽

Photosynthetic Photon Flux Density ◽

Photon Flux ◽

Photon Flux Density ◽

Light At Night ◽

Sweet Basil

Sweet basil (Ocimum basilicum L.) is primarily used for culinary purposes, but it is also used in the fragrance and medicinal industries. In the last few years, global sweet basil production has been significantly impacted by downy mildew caused by Peronospora belbahrii Thines. Nighttime exposure to red light has been shown to inhibit sporulation of P. belbahrii. The objective of this study was to determine if nighttime exposure to red light from light-emitting diodes (λmax = 625 nm) could increase plant growth (plant height and leaf size) and yield (number and weight of leaves) in basil plants. In two sets of greenhouse experiments, red light was applied at a photosynthetic photon flux density of 60 μmol m−2 s−1 during the otherwise dark night for 10 h (from 2000 to 0600). The results demonstrate that exposure to red light at night can increase the number of basil leaves per plant, plant height, leaf size (length and width), and leaf fresh and dry weight compared with plants in darkness at night. The addition of incremental red light at night has the potential to be cost-effective for fresh organic basil production in controlled environments.

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Morphological Response of Soybean (Glycine max (L.) Merr.) Cultivars to Light Intensity and Red to Far-Red Ratio

Agronomy ◽

10.3390/agronomy9080428 ◽

2019 ◽

Vol 9 (8) ◽

pp. 428 ◽

Cited By ~ 3

Author(s):

Tina Hitz ◽

Jens Hartung ◽

Simone Graeff-Hönninger ◽

Sebastian Munz

Keyword(s):

Cropping Systems ◽

Light Emitting Diode ◽

Red Light ◽

Photosynthetic Photon Flux Density ◽

Photon Flux ◽

Photon Flux Density ◽

Shade Avoidance ◽

Internode Elongation ◽

Morphological Response ◽

Petiole Elongation

In soybean production, the shade avoidance response can affect yield negatively in both mono- and inter-cropping systems due to increased heterogeneity of the crop and lodging. This is mainly regulated by photoreceptors responding to the ratio between red and far-red light (R:FR) and photosynthetic photon flux density (PPFD). In this study, three soybean cultivars were grown under different R:FR and PPFD in a light emitting diode (LED) climate chamber to disentangle the effect of each on morphology and dry matter. Results showed that plant organs were influenced differently and indicated an interaction with the increase in assimilates at high PPFD. Internode elongation was mainly influenced by low PPFD with an additive effect from low R:FR, whereas petiole elongation responded strongly under low R:FR. Hence, petiole elongation can be seen as the main response to the threat of shade (high PPFD and low R:FR) and both petiole and internode elongation as a response to true shade (low PPFD and low R:FR). Interactions between cultivar and light treatment were found for internode length and diameter and leaf mass ratio, which may be unique properties for specific cropping systems.

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