The Role of the Red/Far-Red Ratio in the Response of Tropical Tree Seedlings to Shade

Kwesiga, F.; Grace, John

doi:10.1093/oxfordjournals.aob.a087108

Cited by 105 publications

(64 citation statements)

References 10 publications

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“…Despite showing some typical shade responses, these species did it to a smaller extent than observed for the early-successional species. Similar behavior was observed in other studies for other latesuccessional or shade-tolerant species (Fetcher et al 1983, Kwesiga & Grace 1986, Osunkoya et al 1994. It may be that this different extent of responses of earlyand late-successional species is a consequence of differences in the species growth potential.…”

Section: Discussionsupporting

confidence: 87%

“…As reported in other studies (Augspurger 1984, Court & Mitchell 1989, Kwesiga & Grace 1986, Popma & Bongers 1988, Osunkoya & Ash 1991, plants in shade had lower height, internode number, leaf area and dry mass compared with sunexposed plants. For six of the studied species, RGR was reduced more in NS than AS, probably because the NS treatment was more severe than AS treatment as a result of a slightly lower irradiance.…”

Section: Discussionsupporting

confidence: 82%

“…However, although it is know that the spectral composition of radiation changes as it is filtered by green canopies, most studies on shade effects have been restricted to investigations of the effects of decreasing the photon flux density without ascribing for changes in spectral composition (Osunkoya & Ash 1991, Thompson et al 1992, Walters et al 1993, Osunkoya et al 1994, Bartlett & Remphrey 1998, Reich et al 1998. Exceptions are the studies of Kwesiga & Grace (1986), Kitajima (1994), Tinoco-Ojanguren & Pearcy (1995) and Lee et al (1996), where natural shade was simulated under experimental conditions by reducing both photon flux density and red/far-red ratio. Although Kitajima (1994) found that reduced red/far-red ratio did not affect growth in any of the thirteen species studied, all of the other studies indicated that growth was significantly influenced by light quality, although the specific pattern of response varied among species.…”

Section: Introductionmentioning

confidence: 99%

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Seedling growth of fifteen Brazilian tropical tree species differing in successional status

Souza

Válio

2003

Rev. bras. Bot.

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-(Seedling growth of fifteen Brazilian tropical tree species differing in successional status). Growth of seedlings of fifteen tropical tree species representative, at the adult stage, of different successional positions, was studied under field conditions. Seedlings were grown in three treatments: full sun (FS), artificial shade imposed by neutral screens (AS) and natural shade imposed by a closed canopy in a Forest Reserve in Southeast Brazil (NS). Most of the studied species survived in both shade treatments, although their growth was severely affected. Decreases in height, internode numbers, dry weight, leaf area, root:shoot ratio (R:S) and increases in leaf mass ratio (LMR), leaf area ratio (LAR) and specific leaf area (SLA) were common responses to shade. Relative growth rates (RGRs) and net assimilation rates (NARs) were consistently lower in the shaded treatments than in full sun. RGR was significantly correlated with NAR in the FS and NS treatments, whereas it was correlated with LAR in the AS treatment. Natural shade had more severe effects than artificial shade on leaf area reduction and RGR. Between-species differences in R:S, LMR, SLA and LAR were not related to the successional status of species. However, there was a tendency for early-successional species to have higher RGRs than late successional ones, regardless of the light environment. Late-successional species also showed less pronounced responses to shade than early ones. The characteristics presented by the late-successional species may be associated with shade tolerance, enabling their persistence under dense canopies.Key words -Seedling growth, shade, shade tolerance, successional species, tropical tree species RESUMO -(Crescimento de plântulas de quinze espécies árboreas tropicais pertencentes a diferentes estádios sucesionais). O crescimento de plântulas de quinze espécies arbóreas tropicais pertencentes a diferentes estádios sucessionais foi estudado sob condições de campo. As plântulas foram cultivadas sob tratamentos de radiação plena, sombreamento artificial proporcionado por telas sombrite e sombreamento natural imposto por dossel vegetal na Reserva Municipal de Santa Genebra em Campinas, SP, Brasil. A maioria das espécies estudadas sobreviveu aos tratamentos de sombreamento, com marcantes alterações no crescimento. Reduções de altura, número de entrenós, massa seca, área foliar e razão raiz/parte aérea (R/PA) foram respostas freqüentes ao sombreamento, assim como também aumentos da razão de massa foliar (RMF), razão de área foliar (RAF) e área foliar específica (AFE). As taxas de crescimento relativo (TCRs) e as taxas de assimilação líquida (TALs) apresentaram-se consistentemente mais baixas nos tratamentos de sombreamento. TCR se mostrou significativamente correlacionada com TAL nos tratamentos de radiação plena e sombreamento natural e com RAF no tratamento de sombreamento artificial. O sombreamento natural teve efeitos mais severos na redução da área foliar e da TCR. As diferenças inter-específicas nos parâmetros R/PA,...

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Section: Discussionsupporting

confidence: 87%

Section: Discussionsupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

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Seedling growth of fifteen Brazilian tropical tree species differing in successional status

Souza

Válio

2003

Rev. bras. Bot.

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“…1A). Increased leaf area in response to +FR has been observed in other species such us Cucumis sativus (Ló pez Juez et al, 1990), Taraxacum officinale (Cogliatti and Sánchez, 1987), Terminalia ivorensis (Kwesiga and Grace, 1986), and Petunia axilaris (Casal et al, 1987), and for some leaf positions in Arabidopsis (Robson et al, 1993). However, the opposite pattern has also been found (Kasperbauer, 1971;Holmes and Smith, 1977b;Frankland and Letendre, 1978;Robson et al, 1993;Devlin et al, 1999), suggesting that the actual effect may depend on the species and growing conditions.…”

Section: Discussionmentioning

confidence: 78%

Phytochrome B Enhances Photosynthesis at the Expense of Water-Use Efficiency in Arabidopsis

et al. 2009

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In open places, plants are exposed to higher fluence rates of photosynthetically active radiation and to higher red to far-red ratios than under the shade of neighbor plants. High fluence rates are known to increase stomata density. Here we show that high, compared to low, red to far-red ratios also increase stomata density in Arabidopsis (Arabidopsis thaliana). High red to farred ratios increase the proportion of phytochrome B (phyB) in its active form and the phyB mutant exhibited a constitutively low stomata density. phyB increased the stomata index (the ratio between stomata and epidermal cells number) and the level of anphistomy (by increasing stomata density more intensively in the adaxial than in the abaxial face). phyB promoted the expression of FAMA and TOO MANY MOUTHS genes involved in the regulation of stomata development in young leaves. Increased stomata density resulted in increased transpiration per unit leaf area. However, phyB promoted photosynthesis rates only at high fluence rates of photosynthetically active radiation. In accordance to these observations, phyB reduced long-term water-use efficiency estimated by the analysis of isotopic discrimination against 13 CO 2 . We propose a model where active phyB promotes stomata differentiation in open places, allowing plants to take advantage of the higher irradiances at the expense of a reduction of water-use efficiency, which is compensated by a reduced leaf area.

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“…The results of other studies, in which the effects of light intensity were separated from those of light quality are not consistent [30,39]. The ability to respond to modifications in the R/FR-ratio by changes in growth patterns seems to depend on the investigated species and its shade tolerance [26,28]. Against this background the objective of the present study was to investigate in a shading experiment (i) how shading comparable to the light conditions below the canopy of a heavily thinned pure Norway spruce (Picea abies [L.] Karst.)…”

Section: Introductionmentioning

confidence: 89%

Growth and biomass partitioning of Fagus sylvatica L. and Quercus robur L. seedlings in response to shading and small changes in the R/FR-ratio of radiation

Ammer

2003

Ann. For. Sci.

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-The effects of shading levels, comparable to the light quantity and quality below the canopy of a Norway spruce (Picea abies [L.] Karst.) stand on one year old European beech (Fagus sylvatica L.) and pendunculate oak (Quercus robur L.) were tested. The treatments were: shading of plants exposed to "natural shade" by using green synthetic nets (PAR reduced to 32.6%, R/FR-ratio 1.04), shading of plants exposed to "neutral shade" by using black nets (PAR reduced to 24.7%, R/FR-ratio 1.13), no shading (control, PAR 100%, R/FR-ratio 1.15). Beech seedlings showed a strong decrease in height, diameter, stem-, branch-, leaf-and root dry mass with decreasing light quantity. Neither growth rates nor total yield indicated an impact of slightly changed light quality (R/FR-ratio 1.04) on growth and biomass partitioning of beech. Relative growth rate of the main stem dry mass of oak was considerably higher for the seedlings of the shade treatment with the reduced R/FR-ratio than for the control and the other shade treatment whereas branch dry biomass exposed to changed light quantity and quality was reduced disproportional, resulting in the lowest branch-stem-ratio. The tallest oak seedlings were found under the green nets (treatment with reduced light quantity and quality), whereas the control showed the shortest seedlings. . Les traitements furent les suivants : plants soumis à une « ombre naturelle » en utilisant des filets synthétiques verts (réduction du PAR à 32,6 %, rapport R/FR 1,04) ; plants soumis à une « ombre neutre », en utilisant des filets noirs (réduction de PAR à 24,6 %, rapport R/FR 1,13) ; pas d'ombrage (témoin PAR 100 %, rapport R/FR 1,15). Pour les plants de hêtre, la réduction de la quantité de lumière s'est traduite par une forte diminution de la hauteur et du diamètre, ainsi que du poids sec des tiges, branches, feuilles et racines. Un faible changement de la qualité de la lumière (rapport R/FR de 1,04) n'a pas d'effet sur la croissance et la répartition de la biomasse. En ce qui concerne les plants de chêne, la croissance en matière sèche de la tige principale est proportionnellement plus élevée pour le traitement ombrage avec rapport R/FR réduit que pour le témoin ou l'autre traitement d'ombrage. Un changement en quantité et qualité de la lumière induit donc une réduction du rapport branche/tige. On obtenait les plants de chêne les plus grands sous filet vert (traitement avec réduction en quantité et qualité de la lumière) alors que les plus petits étaient dans le témoin. qualité de la lumière / ombrage / chêne pédonculé / hêtre

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The Role of the Red/Far-Red Ratio in the Response of Tropical Tree Seedlings to Shade

Cited by 105 publications

References 10 publications

Seedling growth of fifteen Brazilian tropical tree species differing in successional status

Seedling growth of fifteen Brazilian tropical tree species differing in successional status

Phytochrome B Enhances Photosynthesis at the Expense of Water-Use Efficiency in Arabidopsis

Growth and biomass partitioning of Fagus sylvatica L. and Quercus robur L. seedlings in response to shading and small changes in the R/FR-ratio of radiation

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