Special Issue "Applications of Different Light Spectra in Growing Forest Tree Seedlings"

A special issue of Forests (ISSN 1999-4907). This special issue belongs to the section "Forest Ecophysiology and Biology".

Deadline for manuscript submissions: closed (31 December 2020).

Special Issue Editor

Dr. Johanna Riikonen
Website
Guest Editor
Natural Resources Institute Finland (Luke), Neulaniementie 5, 70200 Kuopio, Finland
Interests: forest tree species; LED lighting; nursery production; photobiology; plant physiology; year-round seedling production
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Special Issue Information

Dear Colleagues,

Light intensity and wavelength distribution and duration are amongst the most important factors affecting the success of plant production in different cultivation systems. Experiments conducted mostly on crop species but also on a smaller scale on forest tree species have shown that plant production and quality can be optimized by manipulating the spectral composition of light. However, the development of applications for enhancing seedling quality and production efficiency in forest tree nurseries by using different light spectra only began recently. For example, a growing interest in the year-round production of seedlings under controlled conditions has created a need for cost-efficient and environmental friendly cultivation protocols. The aim of this Special Issue of Forests is to increase our understanding of the role of light quality in seedling growth and development, and in this way to promote the development of new applications for production of healthy and vigorous seedlings. Manuscript submissions focusing on any aspect of using different light spectra in growing forest tree seedlings are welcome and encouraged.

Dr. Johanna Riikonen
Guest Editor

Manuscript Submission Information

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Keywords

  • Forest tree species
  • Nursery production
  • Light quality
  • Spectral composition
  • Year-round production
  • Seedling quality

Published Papers (4 papers)

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Research

Open AccessArticle
Plasticity of Leaf Traits of Juglans regia L. f. luodianense Liu et Xu Seedlings Under Different Light Conditions in Karst Habitats
Forests 2021, 12(1), 81; https://doi.org/10.3390/f12010081 - 13 Jan 2021
Abstract
This study examined the effects of light intensity on the plasticity of the leaves of Juglans regia f. luodianense seedlings in karst habitat and how they respond to changes in light intensity. The light intensity of 1-year-old seedlings of J. regia f. luodianense [...] Read more.
This study examined the effects of light intensity on the plasticity of the leaves of Juglans regia f. luodianense seedlings in karst habitat and how they respond to changes in light intensity. The light intensity of 1-year-old seedlings of J. regia f. luodianense in different niches in a karst area was set as 100% (bare land), 75% (forest margin), 50% (forest gap), and 25% (under forest) of natural light. The material harvested after four months was compared to analyze the differences in various morphological characteristics, biomass allocation, and physiological characteristics of the leaves of seedlings of J. regia f. luodianense, and a comprehensive evaluation of the plasticity indexes was conducted. The results showed that under moderate (50%) full light intensity, the leaf area, specific leaf area, leaf biomass, and chlorophyll content increased, and improved photosynthesis and promoted the accumulation of free proline content and peroxidase (POD) activity. The accumulation of malondialdehyde was also the lowest in this treatment, indicating that the plants had the strongest adaptability under this light intensity. Moreover, under high (75%) full light intensity, the above functional characteristics of plants showed good performance. Under low (25%) full light intensity, plants also had higher specific leaf area, leaf biomass, and photosynthetic parameters. However, under full light, the cell membrane permeability decreased, the chlorophyll accumulation was the lowest, and the photosynthetic index was seriously inhibited. Our results showed that the plasticity of morphological characters was greater than that of biomass allocation and physiological characters; POD activity and stomatal conductance were the highest, followed by leaf area and chlorophyll b, whereas the plasticity of palisade tissue/sponge tissue thickness and lower-epidermis thickness were the lowest. In summary, there are evident differences in the sensitivity and regulation mechanisms of morphological characteristics, biomass allocation, and physiological indices of the seedling leaves of J. regia f. luodianense in response to light intensity. During the stage of seedling establishment, only the plants in the bare ground under full light can be induced to show obvious inhibition of phenotypic traits. In contrast, the plants in the forest margins and gaps and under the forest habitats under light intensity can regulate their own characteristics to maintain their growth and development. The wide light range and strong plasticity of the species might be two of the important reasons for its existence in a highly heterogeneous karst habitat. Full article
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Open AccessArticle
Light Shock Stress after Outdoor Sunlight Exposure in Seedlings of Picea abies (L.) Karst. and Pinus sylvestris L. Pre-Cultivated under LEDs—Possible Mitigation Treatments and Their Energy Consumption
Forests 2020, 11(3), 354; https://doi.org/10.3390/f11030354 - 21 Mar 2020
Abstract
Year-round cultivation under light emitting diodes (LEDs) has gained interest in boreal forest regions like Fenno-Scandinavia. This concept offers forest nurseries an option to increase seedling production normally restricted by the short vegetation period and the climate conditions. In contrast to some horticultural [...] Read more.
Year-round cultivation under light emitting diodes (LEDs) has gained interest in boreal forest regions like Fenno-Scandinavia. This concept offers forest nurseries an option to increase seedling production normally restricted by the short vegetation period and the climate conditions. In contrast to some horticultural crops which can be cultivated entirely under LEDs without sunlight, forest seedlings need to be transplanted outdoors in the nursery at a very young age before being outplanted in the field. Juvenile plants are less efficient using absorbed light and dissipating excess energy making them prone to photoinhibition at conditions that usually do not harm mature plants. The outdoor transfer can cause stress in the seedlings due to high sunlight intensity and exposure to ultraviolet (UV) radiation not typically present in the spectra of LED lamps. This study tested possible treatments for mitigating light shock stress in seedlings of Picea abies (L.) Karst. and Pinus sylvestris L. transplanted from indoor cultivation under LEDs to outdoor sunlight exposure. Three sowings were carried out in 2014 (May and June) and 2015 (May) cultivating the seedlings during five weeks under LED lights only. Afterwards, higher light intensity or UV radiation treatments were applied during one week in order to adapt the seedlings to natural outdoor conditions. After transplanting a transition phase was introduced using shading cloths for one or three weeks as outdoor treatments for light shock mitigation. Chlorophyll fluorescence (ChlF) levels and CO2 assimilation rates were measured before transplanting and followed outdoors during 5 weeks. The ChlF results revealed stress symptoms in the photoreceptors during the first days after transplanting. After five weeks outdoors the ChlF levels had recovered and the light saturation points had shifted, allowing higher CO2 assimilation rates. By the end of the vegetation period the morphological attributes showed no major differences between treatments. Full article
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Open AccessArticle
Comparative Transcriptome Analyses of Gene Response to Different Light Conditions of Camellia oleifera Leaf Using Illumina and Single-Molecule Real-Time-Based RNA-Sequencing
Forests 2020, 11(1), 91; https://doi.org/10.3390/f11010091 - 11 Jan 2020
Abstract
Camellia oleifera Abel. is a critical oil tree species. Camellia oil, which is extracted from the seeds, is widely regarded as a premium cooking oil, with the content of oleic acid being over 80%. Light is thought to be one of the largest [...] Read more.
Camellia oleifera Abel. is a critical oil tree species. Camellia oil, which is extracted from the seeds, is widely regarded as a premium cooking oil, with the content of oleic acid being over 80%. Light is thought to be one of the largest essential natural components in the regulation of plant developmental processes, and different light qualities can considerably influence plant physiological and phenotypic traits. In this research, we examined the growth and physiological responses of C. oleifera “MIN 43” cultivar plantlets to three different wavelengths of light, containing white, red, and blue light, and we utilized the combination of the PacBio single-molecule real-time (SMRT) and Illumina HiSeq RNA sequencing to obtain the mRNA expression profiles. The results showed that plantlets growing under blue light conditions displayed superior growth performance, including stimulated enhancement of the leaf area, increased leaf number, increased chlorophyll synthesis, and improved photosynthesis. Furthermore, SMAT sequencing created 429,955 reads of inserts, where 406,722 of them were full-length non-chimeric reads, and 131,357 non-redundant isoforms were produced. Abundant differentially expressed genes were found in leaves under different light qualities by RNA-sequencing. Gene expression profiles of actin, dynein, tubulin, defectively organized tributaries 3 (DOT3), and ADP ribosylation factor 5 (ARF5) were associated with the greatest leaf performance occurring under blue light conditions. Moreover, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis identified hundreds of pathways involved in different light conditions. The pathways of the plant circadian rhythm and hormone signal transduction were associated with different light quality responses in C. oleifera. Phytochrome B (PHYB), constitutively photomorphogenic 1 (COP1), long hypocotyl 5 (HY5), auxin/indole-3-acetic acid (AUX/IAA), Gretchen Hagen 3 (GH3), and small auxin-up RNA (SAUR), which were differentially expressed genes involved in these two pathways, play a vital role in responses to different wavelengths of light in C. oleifera. In addition, blue light significantly promotes flavonoid biosynthesis via changing expression of related genes. Full article
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Open AccessArticle
Growth, Nutrient Assimilation, and Carbohydrate Metabolism in Korean Pine (Pinus koraiensis) Seedlings in Response to Light Spectra
Forests 2020, 11(1), 44; https://doi.org/10.3390/f11010044 - 31 Dec 2019
Cited by 6
Abstract
A need is growing to plant superior Korean pine (Pinus koraiensis Siebold & Zucc.) seedlings to cope with the degradation of secondary forests in Northeast Eurasia. The goal of this study was to detect the physiological effect on the quality of Korean [...] Read more.
A need is growing to plant superior Korean pine (Pinus koraiensis Siebold & Zucc.) seedlings to cope with the degradation of secondary forests in Northeast Eurasia. The goal of this study was to detect the physiological effect on the quality of Korean pine seedlings exposed to a range of spectra. One-year-old seedlings (n = 6) were cultured in three light-emitting diode (LED) spectra (69‒77 μmol m−2 s−1) of 13.9% red (R) + 77.0% green (G) + 9.2% blue (B) (R1BG5), 26.2% R + 70.2% G + 3.5% B (R2BG3), and 42.3% R + 57.3% G + 0.4% B (R3BG1). The spectrum of high-pressure sodium (HPS) lamps (43.9% R + 54.7% G + 1.5 B) was taken as the reference. Results showed that LED-lighting resulted in shorter seedlings with a greater diameter, shoot biomass, assessed quality, and sturdiness compared to those under the HPS-lighting. The R3BG1 spectrum reduced the shoot nitrogen (N) deficiency induced by the HPS spectrum, while the R1BG5 treatment induced a steady-state uptake of N and phosphorus (P) in whole-plant organs. The R1BG5 spectrum also resulted in a higher soluble sugar concentration and higher activities of glutamine synthetase and acid phosphatase in needles compared to the control. Seedlings in the R2BG3 spectrum had the highest concentrations of chlorophyll and soluble protein in the leaves. Overall, the R-high LED-spectrum could stimulate biomass accumulation in shoot, but meanwhile resulted in a P deficiency. Hence, the LED lighting in the R1BG5 spectrum is recommended to promote the quality of Korean pine seedlings. Full article
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