scholarly journals Growth responses of the nuisance algae Gonyostomum semen (Raphidophyceae) to DOC and associated alterations of light quality and quantity

2019 ◽  
Vol 82 (3) ◽  
pp. 241-251 ◽  
Author(s):  
CHC Hagman ◽  
B Skjelbred ◽  
JE Thrane ◽  
T Andersen ◽  
HA de Wit
1996 ◽  
Vol 74 (3) ◽  
pp. 383-390 ◽  
Author(s):  
John Hoddinott ◽  
Rickey Scott

Plant growth responds to light quality, as evaluated by the red/far-red (R/FR) quantum flux ratio, and to the level of CO2. Pinus banksiana, Picea mariana and Picea glauca seedlings were raised at 350, 700, or 1050 μL∙L−1 CO2 and high or low R/FR ratios and growth was measured over a 16-week growth period. Far-red rich light enhanced the whole plant and height relative growth rates of Pinus banksiana. The three species showed species specific responses in plant organ relative growth rates and partitioning ratios. On the basis of their biomass partitioning the species would be ranked Pinus banksiana < Picea mariana < Picea glauca for shade tolerance. In commercial operations, seedlings grown for outplanting are selected, in part, on the basis of plant form as described by the stem height/diameter ratio. More desirable ratios were obtained at ambient CO2 concentrations for Pinus banksiana and Picea mariana in red rich light and for Picea glauca in far-red rich light. Keywords: seedling growth, light quality, CO2 enrichment.


HortScience ◽  
2015 ◽  
Vol 50 (1) ◽  
pp. 112-118 ◽  
Author(s):  
Celina Gómez ◽  
Cary A. Mitchell

Seedlings of six tomato (Solanum lycopersicum) cultivars (‘Maxifort’, ‘Komeett’, ‘Success’, ‘Felicity’, ‘Sheva Sheva’, and ‘Liberty’) were grown monthly for 2-week treatment periods to determine photomorphogenic and developmental responses to different light-quality treatments from supplemental lighting (SL) across changing solar daily light integrals (DLIs). Seedlings were grown in a glass-glazed greenhouse at a midnorth latitude (lat. 40° N, long. 86° W) under one of five lighting treatments: natural solar light only (control), natural + SL from a 100-W high-pressure sodium (HPS) lamp, or natural + SL from arrays of red and blue light-emitting diodes (LEDs) using 80% red + 20% blue, 95% red + 5% blue, or 100% red. Varying solar DLI occurred naturally for all treatments, whereas constant DLI of 5.1 mol·m−2·d−1 was provided for all SL treatments. Supplemental lighting increased hypocotyl diameter, epicotyl length, shoot dry weight, leaf number, and leaf expansion relative to the control, whereas hypocotyl elongation decreased when SL was applied. For all cultivars tested, the combination of red and blue in SL typically increased growth of tomato seedlings. These results indicate that blue light in SL has potential to increase overall seedling growth compared with blue-deficient LED SL treatments in overcast, variable-DLI climates.


2020 ◽  
Vol 11 ◽  
Author(s):  
Kiki Spaninks ◽  
Jelmer van Lieshout ◽  
Wim van Ieperen ◽  
Remko Offringa

In vertical farming, plants are grown in multi-layered growth chambers supplied with energy-efficient LEDs that produce less heat and can thus be placed in close proximity to the plants. The spectral quality control allowed by LED lighting potentially enables steering plant development toward desired phenotypes. However, this requires detailed knowledge on how light quality affects different developmental processes per plant species or even cultivar, and how well information from model plants translates to horticultural crops. Here we have grown the model dicot Arabidopsis thaliana (Arabidopsis) and the crop plant Solanum lycopersicum (tomato) under white or monochromatic red or blue LED conditions. In addition, seedlings were grown in vitro in either light-grown roots (LGR) or dark-grown roots (DGR) LED conditions. Our results present an overview of phenotypic traits that are sensitive to red or blue light, which may be used as a basis for application by tomato nurseries. Our comparative analysis showed that young tomato plants were remarkably indifferent to the LED conditions, with red and blue light effects on primary growth, but not on organ formation or flowering. In contrast, Arabidopsis appeared to be highly sensitive to light quality, as dramatic differences in shoot and root elongation, organ formation, and developmental phase transitions were observed between red, blue, and white LED conditions. Our results highlight once more that growth responses to environmental conditions can differ significantly between model and crop species. Understanding the molecular basis for this difference will be important for designing lighting systems tailored for specific crops.


1999 ◽  
Vol 15 (6) ◽  
pp. 827-839 ◽  
Author(s):  
J. W. Dalling ◽  
C. E. Lovelock ◽  
S. P. Hubbell

Traditional shade house experiments that expose plants to relatively uniform irradiance and light quality are inadequate to characterize the morphological, allocational and physiological plasticity that seedlings show to different gap environments. Here the design of a pot experiment is described that simulates the daily time course of irradiance and light quality in idealized gaps of six different sizes. Differences in response to gap size are illustrated using data from two pioneer species, Ochroma pyramidale, which recruits exclusively in large gaps and clearings, and Luehea seemannii, which colonizes small branchfall gaps as well as large gaps. Ochroma outperformed Luehea in relative growth rate in all except the smallest simulated gap size. Ochroma's superior performance in the larger gaps could be attributed to a larger proportional investment in leaf biomass (i.e. a higher leaf area ratio, LAR), and higher photosynthetic rates both on a leaf area and leaf mass basis. In the smallest simulated gaps LAR was not significantly different between the species, but Ochroma maintained a higher net assimilation rate. These results fail to support the suggestion that gap partitioning among pioneer species arises directly from morphological and biochemical specialization to particular gap light environments. Instead, it is suggested that partitioning may result from a trade-off between seedling growth and mortality determined by species allocational patterns and mediated by interactions with herbivores and pathogens.


Horticulturae ◽  
2019 ◽  
Vol 5 (2) ◽  
pp. 31 ◽  
Author(s):  
Thomas E. Marler

The role of seed imbibition and light during germination are not known for the critically endangered Serianthes nelsonii Merr. Scarified seeds were pre-soaked in gibberellic acid (GA3) up to 300 mg/L and nitrate solutions of 3000 mg/L to determine if germination was influenced by these treatments. Scarified and imbibed seeds were incubated in high red:far red and low red:far red light to determine the influence of light quality on germination traits. The GA3 and nitrate treatments did not influence germination percentage or timing, but did increase the height of newly emerged seedlings. Moreover, GA3 extended the longevity of cotyledons and shortened the window of time that seedlings required to resume height growth. These growth responses were not sustained, and all seedlings reached heights of 30 cm at a similar number of weeks. The light treatments did not influence any of the germination response traits. The results indicate that imbibing seeds with chemical solutions and providing light in a range of light quality treatments exerted a minimal influence on S. nelsonii seed germination behaviors. Imbibing seeds with water and germinating in darkness is sufficient for achieving the germination of this endangered tree species.


HortScience ◽  
1992 ◽  
Vol 27 (11) ◽  
pp. 1177d-1177
Author(s):  
Heather. H. Friend ◽  
Arne Sæbø ◽  
Dennis R. Decoteau

Previous research has demonstrated that watermelon plants are sensitive to changes in light quality, as suggested by an individual treatment of plants with 15-min of end-of-day (EOD) red (R)and far-red (FR) light. FR-induced growth responses (i.e., petiole elongation, internode elongation, reduced petiole angles) were reversed by immediately following the FR light treatment with R light implicating phytochrome as the light quality perception mechanism. The objective of the present experiment was to determine the influence of individual and multiple FR light treatments (each treatment of 15-min duration) during the light and dark phase of the photoperiod on photomorphogenic growth responses of young watermelon plants. Light regulated growth responses of watermelon were influenced by the timing and the number of light quality exposures during the light or dark phase of the photoperiod. Individual FR treatments during the light phase except for the EOD exposure did not affect plant growth responses. In contrast, individual FR treatments at selected intervals during the dark period affected plant development. The most effective individual FR treatment to induce growth responses was at the beginning of the dark period, with decreasing responses as the FR treatment was delayed into the dark period. Multiple exposures of FR during the dark slightly increased growth responses as compared to a single EOD FR treatment.


HortScience ◽  
1992 ◽  
Vol 27 (12) ◽  
pp. 1269-1271 ◽  
Author(s):  
J.C. Vlahos ◽  
G.F.P. Martakis ◽  
E. Heuvelink

The effects of supplementary irradiance (20 μmol·s-1·m-2 for 6 hours) with incandescent light (I) or fluorescent compact gas-discharge lamps (CF) vs. a basic irradiance (96 μmol·s-1·m-2 for 12 h) with fluorescent (F) light at 17 or 25C was studied for Achimenes hybrids `Flamenco', `Hilda', and `Rosenelfe'. The additional I increased leaf area (LA) and plant dry weight (DW) in `Hilda' and `Rosenelfe' and promoted stem elongation in all three cultivars. Additional F had no effect on DW. However, depending on cultivar, responses for LA varied. An increase in the number of flowers was promoted only in `Rosenelfe' by I and CF compared with the control. In all cultivars, the supplementary CF, when compared with the I, reduced LA and DW. LA was significantly larger and DW higher at higher temperature, except for `Rosenelfe', where DW was not influenced and LA was smaller at the higher temperature. All three cultivars produced a longer stem and more flowers at the higher temperature. Calculated growth responses were influenced by an interaction between temperature and cultivar.


1994 ◽  
Vol 29 (2) ◽  
pp. 159-166 ◽  
Author(s):  
Brita M. Svensson ◽  
Britt Floderus ◽  
Terry V. Callaghan

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