17 documents found, page 1 of 2

Do soil fertilization and forest canopy foliage affect the growth and photosynt...

Most Amazonian soils are highly weathered and poor in nutrients. Therefore, photosynthesis and plant growth should positively respond to the addition of mineral nutrients. Surprisingly, no study has been carried out in situ in the central Amazon to address this issue for juvenile trees. The objective of this study was to determine how photosynthetic rates and growth of tree saplings respond to the addition of m...

Metabolismo de Ureídeos Em Plantas Superiores

Concentration of photosynthetic pigments and chlorophyll fluorescence of mahoga...

This study was carried out in a plantation of a degraded area in Central Amazon, Brazil, in order to assess environmental light effects on leaf pigment concentrations and chlorophyll a fluorescence in mahogany (Swietenia macrophylla King) and tonka bean (Dipteryx odorata Aubl. Willd). Three-year old saplings were grown in an open site (sun) with maximum radiation of approximately 2000 μmol m-2 s-1 and under the...

Maximum carboxylation velocity of rubisco and maximum rate of electron transpor...

Light availability is one of the main factors that limits photosynthetic rates in saplings in the forest understory. The aims of this study were to determine how photosynthetic parameters (maximum carboxylation velocity of Rubisco – Vc-max and maximum rate of electron transport – Jmax) respond to irradiance, temperature and diurnal variations in the physical environment. Gas exchange data were collected between...

Photosynthesis and photoinhibition in mahogany and acariquara as a function of ...

Photoinhibition may be exacerbated by stress factors such as high temperature. The aim of the work was to determine the effects of temperature and irradiance on photosynthesis and photoinhibition in mahogany (Swietenia macrophylla King) and acariquara (Minquartia guianensis Aubl.). Also to assess the effect of irradiance and temperature on the recovery from photoinhibition at low irradiance. Sapling were grown ...

Photosynthesis and biomass accumulation in carapa surinamensis (Meliaceae) in r...

Climate models predict an increase in atmospheric CO2 concentration and prolonged droughts in some parts of the Amazon, but the effect of elevated CO2 is still unknown. Two experiments (ambient CO2 ‒ 400 ppm and elevated CO2 ‒ 700 ppm) were conducted to assess the effect of drought (soil at 50% field capacity) on physiological parameters of Carapa. At ambient CO2 concentration, light-saturated net photosyntheti...

Leaf phenology, growth and photosynthesis in Pseudobombax munguba (Malvaceae)

Munguba (Pseudobombax munguba) is a tree often found in low-land forests of the Amazon region, and there is a paucity of data regarding its ecophysiology. The aim of this work was to determine photosynthetic rates and growth of munguba saplings and to describe leaf phenology of a munguba tree. In greenhouse-grown saplings, diameter growth, leaf expansion, photosynthesis and stomatal conductance were determined....

Tree growth, wood and bark water content of 28 Amazonian tree species in respon...

Pole diameter and wood density are variables commonly used in allometric equations to estimate tree biomass and carbon stocks in tropical forests. The effect of variations in tree water content on pole diameters is often disregarded in allometric equations. This study aimed to determine the effect of rainfall seasonality on tree growth, stem wood and bark water content and to assess the relationship between wat...

Leaf gas exchange and carbohydrates in tropical trees differing in successional...

Monoculture and mixed stands of mahogany (Swietenia macrophylla King) and tonka bean (Dipteryx odorata Willd.) trees were established on degraded land in central Amazonia to compare leaf gas exchange parameters between plants grown in sunlight in an open field and in shade beneath a balsa wood (Ochroma pyramidale Cav.) canopy. Shading increased specific leaf area by about 50% in both species. Shading reduced he...

Primary metabolism components of seeds from Brazilian Amazon tree species

The contents of the main components of the primary metabolism (soluble sugars, starch, proteins, oils, fatty acids) and minerals (P, Ca, Mg, K, Fe, Zn, Mn, Cu) were characterized in seeds of five Brazilian Amazon tree species (Andira parviflora, Bertholletia excelsa, Helicostylis tomentosa, Hymenaea parviflora, and Parkia pendula). Soluble sugar contents were high in P. pendula seeds (14%), whereas starch predo...