SPAD-502 readings in response to photon fluence in leaves with different chlorophyll content

Nascimento, Helena Cristina Santos; Marenco, Ricardo Antonio

doi:10.1590/s0034-737x2010000500008

Cited by 7 publications

(2 citation statements)

References 19 publications

(23 reference statements)

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“…Values of daily photon fluence recorded during this study are within the range of daily irradiance reported by others for central Amazonia (Ribeiro et al 1982, Nascimento andMarenco 2010). As Ψ LP in the WWS treatment (soil at field capacity) was -300 kPa in both species, I concluded that there was an imbalance between the soil water tension and Ψ LP , in agreement with the findings of Donovan et al (2001) for several species (e.g.…”

Section: Environmental Conditions During the Experimentssupporting

confidence: 92%

Photosynthetic parameters and growth in seedlings of Bertholletia excelsa and Carapa guianensis in response to pre-acclimation to full sunlight and mild water stress

Azevedo

2014

Acta Amaz.

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Light and water are important factors that may limit the growth and development of higher plants. The aim of this study was to evaluate photosynthetic parameters and growth in seedlings of Bertholletia excelsa and Carapa guianensis in response to pre-acclimation to full sunlight and mild water stress. I used six independent pre-acclimation treatments (0, 90 (11h15-12h45), 180 (10h30-13h30), 360 (09h00-15h00), 540 (07h30-16h30) and 720 min (06h00-18h00)) varying the time of exposure to full sunlight (PFS) during 30 days, followed by whole-day outdoor exposure for 120 days. Before PFS, the plants were kept in a greenhouse at low light levels (0.8 mol m -2 day -1). The PFS of 0 min corresponded to plants constantly kept under greenhouse conditions. From the beginning to the end of the experiment, each PFS treatment was submitted to two water regimes: moderate water stress (MWS, pre-dawn leaf water potential (Ψ L ) of -500 to -700 kPa) and without water stress (WWS, Ψ L of -300 kPa, soil kept at field capacity). Plants under MWS received only a fraction of the amount of water applied to the well-watered ones. At the end of the 120-day-period under outdoor conditions, I evaluated light saturated photosynthesis (A max ), stomatal conductance (g s ), transpiration (E) and plant growth. Both A max and g s were higher for all plants under the PFS treatment. Stem diameter growth rate and A max were higher for C. guianensis subjected to MWS than in well-watered plants. The contrary was true for B. excelsa. The growth of seedlings was enhanced by exposure to full sunlight for 180 minutes in both species. However, plants of B. excelsa were sensitive to moderate water stress. The higher photosynthetic rates and faster growth of C. guianensis under full sun and moderate water stress make this species a promissory candidate to be tested in reforestation programs. KEYWORDS: Amazonia, forest tree species, photosynthesis, stomatal conductanceParâmetros fotossintéticos e crescimento em mudas de Bertholletia excelsa e Carapa guianensis em resposta a pré-aclimatação a pleno sol e estresse hídrico moderado RESUMO A luz e a água são importantes fatores que limitam o crescimento e o desenvolvimento das plantas. O objetivo deste estudo foi avaliar os paâmetros fotossintéticos e o crescimento em mudas de Bertholletia excelsa e Carapa guianensis em resposta a pré-aclimatação à luz solar plena e estresse hídrico moderado. Foram usados seis independentes tratamentos de pré-aclimatação a pleno sol (PFS), sendo estes de (0, 90 (11h15-12h45), 180 (10h30-13h30), 360 (09h00-15h00), 540 (07h30-16h30) e 720 min (06h00-18h00)) durante 30 dias seguidos por um período de exposição a pleno sol de 120 dias durante o dia todo. Antes da PFS, as plantas foram mantidas em casa de vegetação a baixos níveis de luz (0,8 mol m -2 dia -1 ). O PFS de 0 min correspondeu às plantas mantidas constatemente na casa de vegetação. Cada tratamento de PFS foi submetido desde o início até o final do experimento a dois regimes hídricos, denominado de estresse híd...

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Section: Environmental Conditions During the Experimentssupporting

confidence: 92%

Photosynthetic parameters and growth in seedlings of Bertholletia excelsa and Carapa guianensis in response to pre-acclimation to full sunlight and mild water stress

Azevedo

2014

Acta Amaz.

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“…The authors did not find a significant correlation between the measured parameters. However, Nascimento and Marenco (2010) observed that SPAD values may vary in leaves with high levels of chlorophyll, probably due to the uneven distribution of chloroplasts in bright sunlight.…”

Section: Introductionmentioning

confidence: 99%

Chlorophyll meter reading and total nitrogen content applied as topdressing in parts of the crambe plant

Mascarello¹,

Silva²,

Gouveia³

et al. 2016

Afr. J. Biotechnol.

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The present study was aimed to assess the relationship between the reading of the chlorophyll meter and the total nitrogen (N) content in the leaf in different parts of the crambe plant, depending on the doses of nitrogen applied to the canopy. Randomized block design in a split-plot experimental design was used. The plots were composed by five levels of topdressing with nitrogen and the subplots composed of three parts of the plant. The analyzed variables were the values of the simple handheld devices to measure chlorophyll index (SPAD) and N content in the leaf. The nitrogen levels were found to influence the total chlorophyll and nitrogen contents, but there was no correlation between chlorophyll and N contents in the crambe. The middle third of the plant during early flowering was found to be the most suitable location for the analysis of foliar nitrogen in the crambe.

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Silicon uptake by wheat: Effects of Si pools and pH

Gocke

Liang

Sommer

et al. 2013

Z. Pflanzenernähr. Bodenk.

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Silicon (Si), although not considered essential, has beneficial effects on plant growth which are mostly associated with the ability to accumulate amorphous (phytogenic) Si, e.g., as phytoliths. Phytogenic Si is the most active Si pool in the soil-plant system because of its great surface-tovolume ratio, amorphous structure, and high water solubility. Despite the high abundance of Si in terrestrial biogeosystems and its importance, e.g., for the global C cycle, little is known about Si fluxes between soil and plants and Si pools used by plants. This study aims at elucidating the contribution of various soil Si pools to Si uptake by wheat. As pH affects dissolution of Si pools and Si uptake by plants, the effect of pH (4.5 and 7) was evaluated. Wheat was grown on Si-free pellets mixed with one of the following Si pools: quartz sand (crystalline), anorthite powder (crystalline), or silica gel (amorphous). Silicon content was measured in aboveground biomass, roots, and soil solution 4 times in intervals of 7 d. At pH 4.5, plants grew best on anorthite, but pH did not significantly affect Si-uptake rates. Total Si contents in plant biomass were significantly higher in the silica-gel treatment compared to all other treatments, with up to 26 mg g -1 in aboveground biomass and up to 17 mg g -1 in roots. Thus, Si uptake depends on the conversion of Si into plant-available silicic acid. This conversion occurs too slowly for crystalline Si phases, therefore Si uptake from treatments with quartz sand and anorthite did not differ from the control. For plants grown on silica gel, real Si-uptake rates were higher than the theoretical value calculated based on water transpiration. This implies that Si uptake by wheat is driven not only by passive water flux but also by active transporters, depending on Si concentration in the aqueous phase, thus on type of Si pool. These results show that Si uptake by plants as well as plant growth are significantly affected by the type of Si pool and factors controlling its solubility.

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SPAD-502 readings in response to photon fluence in leaves with different chlorophyll content

Cited by 7 publications

References 19 publications

Photosynthetic parameters and growth in seedlings of Bertholletia excelsa and Carapa guianensis in response to pre-acclimation to full sunlight and mild water stress

Photosynthetic parameters and growth in seedlings of Bertholletia excelsa and Carapa guianensis in response to pre-acclimation to full sunlight and mild water stress

Chlorophyll meter reading and total nitrogen content applied as topdressing in parts of the crambe plant

Silicon uptake by wheat: Effects of Si pools and pH

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