Growth and photosynthetic down-regulation in Coffea arabica in response to restricted root volume

Coffee (Coffea arabica L.) plants were grown in small (3-L), medium (10-L) and large (24-L) pots for 115 or 165 d after transplanting (DAT), which allowed different degrees of root restriction. Effects of altered source : sink ratio were evaluated in order to explore possible stomatal and non-stomatal mechanisms of photosynthetic down-regulation. Increasing root restriction brought about large and general reductions in plant growth associated with a rising root : shoot ratio. Treatments did not affect leaf water potential or leaf nutrient status, with the exception of N content, which dropped significantly with increasing root restriction even though an adequate N supply was available. Photosynthesis was severely reduced when plants were grown in small pots; this was largely associated with non-stomatal factors, such as decreased Rubisco activity. At 165DAT contents of hexose, sucrose, and amino acids decreased in plants grown in smaller pots, while those of starch and hexose-P increased in plants grown in smaller pots. Photosynthetic rates were negatively correlated with the ratio of hexose to free amino acids, but not with hexose content. Activities of acid invertase, sucrose synthase, sucrose-P synthase, fructose-1,6- bisphosphatase, ADP-glucose pyrophosphorylase, starch phosphorylase, glyceraldehyde-3-P dehydrogenase, PPi : fructose-6-P 1-phosphotransferase and NADP : glyceraldehyde-3-P dehydrogenase all decreased with severe root restriction. Glycerate-3-P : Pi and glucose-6-P : fructose-6-P ratios decreased accordingly. Photosynthetic down-regulation was unlikely to have been associated directly with an end-product limitation, but rather with decreases in Rubisco. Such a down-regulation was largely a result of N deficiency caused by growing coffee plants in small pots.

Root, shoot and leaf traits of the congeneric Styrax species may explain their distribution patterns in the cerrado sensu lato areas in Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Dry matter production of shoots and root density of two cultivars of Lablab purpureus (L.) Sweet

This experiment was conducted in green house conditions to evaluate the DM accumulation in the shoots and in the roots of two cultivars of Lablab purpureus (L.) Sweet. A 2x3 factorial (two cultivars and three evaluation dates) was conducted according to a randomized complete block design with four replications, being the cultivars Highworth and Rongai evaluated at 42, 56, and 70 days after seedling emergence (DASE). The results indicated that the cvs. Highworth and Rongai have the same pattern of DM accumulation in the shoots. In the upper layer of the soil (0-0.20 in) it was found 38.83% and 43.64% of the DM accumulated in the roots down to 2.00 in depth, in the cvs. Highworth and Rongai, respectively. In the deepest layer (1.80-2.00 in) it was found 3.02% and 1.5% of the DM accumulated in the roots of the cvs. Highworth and Rongai, respectively. The root density showed a striking decrease upper layer from the soil (0-0.2 m) down to the depth of 0.60 0.80 in (from 10.83 to 1.75 cm.cm(-3) in the cv. Highworth and from 10.76 to 1.28 cm.cm(-3) in the cv. Rongai). At the bottom layer (1.80-2.00 in) the root density values were 0.98 cm.cm(-3) and 0.59 cm.cm(-3), respectively for the cvs. Highworth and Rongai. The root/shoot ratios were similar in both cvs. and decreased from 42 to 70 DASE showing that the cvs. evaluated had the same dynamics of DM accumulation.

Respostas fisiológicas de diferentes clones de eucalipto sob diferentes regimes de irrigação

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Preliminary results of a floating subirrigation system (Aquaforest system) as an alternative to conventional tree nurseries

A new methodology for tree seedling production (Aquaforest system) based on a continuous floating subirrigation system was developed and tested using creeks with different nutrient levels. Eucalyptus grandis seedlings were produced in water from polluted and clean creeks, and compared to conventional tree nursery production. The growth variables analyzed in the seedling phase were: survival, height, diameter, shoot and root dry weight, leaf area, and root/shoot ratio. Water and substrate were analyzed, as well as leaf nutritional status. Plant survival was 100% in all treatments. Height and diameter were greater in the higher nutrient water treatment. Leaf area and dry weight of plants produced in the higher nutrient water treatment were similar to those of the control. The results showed that polluted water can represent a good nutrient source. The preliminary results show that the Aquaforest system can be a viable alternative for tree seedling production. (C) 2004 Elsevier B.V. All rights reserved.

Nutrition, dry matter accumulation and partitioning and phosphorus use efficiency of potato grown at different phosphorus levels in nutrient solution

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Utilização de águas residuárias provenientes do tratamento biológico de esgotos domésticos na produção de mudas de Eucalyptus grandis Hill. ex. maiden

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Experimental assessment of Heliconia acuminata growth in a fragmented Amazonian landscape

1 Fragmentation severely alters physical conditions in forest understories, but few studies have connected these changes to demographic impacts on forest species using detailed experimental examination at the individual and population levels.2 Using a 32-month, reciprocal-transplant experiment, we show that individuals of the Amazonian understory herb Heliconia acuminata transplanted into forest fragments lost over 20% of their vegetative shoots, while those transplanted to continuous forest showed a slight gain. The leaf area of plants in fragments also increased at half the rate it did in continuous forest sites.3 It appears that the normal dry season stresses to which forest understorey plants are exposed are greatly exacerbated in fragments, causing plants to shed shoots and leaves.4 the observed shifts in size could help explain why populations in fragments are more skewed towards smaller demographic stage classes than those in continuous forest. These shifts in size structure could also result in reduced abundances of flowering plants, as reproduction in H. acuminata is positively correlated with shoot number.5 Fragmentation-related changes in growth rates resulting from abiotic stress may have significant demographic consequences.

Kinetic parameters of silicon uptake by rice cultivars

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Variabilidade entre genótipos de feijoeiro na eficiência no uso do fósforo

A utilização da variabilidade genética em feijoeiro (Phaseolus vulgaris L.) para eficiência na absorção e utilização de fósforo se mostra como uma alternativa para contornar a deficiência deste elemento em solos de cerrado. Para detectar tais eficiências, foi desenvolvido um experimento em casa de vegetação na Universidade Federal de Uberlândia-MG, entre julho e agosto de 1997. O delineamento experimental foi de blocos casualizados com quatro repetições, em esquema fatorial 8 x 2. Foram avaliados oito genótipos de feijoeiro (BAT 477, Carioca MG, Emgopa 201, Jalo Precoce, Pérola, Rosinha, Roxo e Xamego) e duas doses de P2O5 (24 e 120mg dm-3). Após 45 dias da germinação, foram analisadas a produção de matéria seca da parte aérea e das raízes dos genótipos; conteúdo de fósforo na parte aérea e das raízes; razão raiz:parte aérea e a eficiência no uso do fósforo (valor a), classificando-os em quatro grupos: eficientes e responsivos, não eficientes e responsivos, eficientes e não responsivos e não eficientes e não responsivos. Os genótipos classificados como eficientes na absorção e utilização de fósforo foram BAT 477, Jalo Precoce e Roxo, enquanto que os classificados como responsivos foram os genótipos Carioca MG, Jalo Precoce, Pérola e Roxo.

Uso racional de nutrientes no cultivo hidropônico de amorperfeito

The objective of this work was to evaluate different concentrations of nutritional solution in the hydroponic cultivation of Viola x wittrockiana Gams. The experiment was conducted in DFT hydroponic system, in a completely randomized design with a 5×4 factorial scheme and five nutrient solution concentrations (50, 75, 100, 125 and 150%), four evaluation periods with three replications of three plants for each treatment. Plant height, root length, number of leaves, flowers and floral buttons; fresh and dry weight of shoot and root were determined. The results were submitted to variance analysis, Tukey's test for evaluation periods and regression analysis for nutrient solution. A decrease in the development of the shoot and root was observed with an increase of the number of cultivation days; the greatest number of floral buttons occurred in the third week of cultivation. A reduction in the plant height, root system length, the number of leaves and the fresh and dry weight of shoot was observed generally with the increase of nutrient solution concentration.

Efeito de níveis de fósforo no crescimento inicial, biomassa e atividade in vivo da fosfatase ácida em Lychnophora ericoides Mart

The effect of phosphorus levels on seedling growth, dry and fresh matter production, and in vivo acid phosphatase activity was studied in Lychnophora ericoides cultivated during 130 days after transplanting in a greenhouse. Experimental design was completely randomized, with four P 2O 5 levels (0; 40; 80; 160 mg dm -3 as triple superphosphate) and five replicates of four plants each. The used soil was dystrophic acid dark red latosol. Lychnophora ericoides is responsive to phosphate fertilization with modification in daily relative growth rate, dry matter production and distribution among the plant parts. Acid phosphatase activity had significant and negative correlation with total, leaf and stem dry matter production, as well as with P levels accumulated in the leaf tissue. On the other hand, acid phosphatase activity had significant and positive correlation with root/shoot ratio.

Desenvolvimento Inicial de Plantas de Eucalyptus Platyphylla Submetidas A Níveis de Salinidade

The objective of this study was to evaluate the behavior of morphological Eucalyptus platyphylla when subjected to five levels of soil salinity. The research project was conducted in a greenhouse at the experimental area of the Department of Agricultural Engineering of the FCA / UNESP, Botucatu-SP, utilizing plastic pots filled with soil containing NaCl concentrations, in sufficient quantities to raise the level of electrical conductivity. The experiment was conducted in randomized blocks in factorial scheme 5 x 4, 5 electrical conductivities (1.41, 2.50, 4.50, 6.45 and 8.33 dS m-1) and four repetitions. The results showed that soil salinity did not significantly affect the following parameters: height, green mass and dry matter of shoot, and root and leaf area of the plants.

Above- and below-ground biomass and carbon dynamics in Brazilian Cerrado wet grasslands

Questions: Grasslands are usually neglected as potential carbon stocks, partially due to the lack of studies on biomass and carbon dynamics in tropical grasslands. What is the importance of Brazilian tropical wet grasslands as carbon sinks? Does fire frequency and season affect biomass and carbon allocation in Brazilian wet grasslands? Location: Wet grasslands, tropical savanna, Jalapão, Tocantins, northern Brazil. Methods: We determined biomass above- and below-ground, estimated carbon stocks in biennially burned plots (B2) and plots excluded from fire for 4 yr (B4). Moreover, we determined biomass in both rainy and dry seasons. Samples were 0.25 m × 0.25 m × 0.2 m (eight samples per treatment, applying a nested design, total of 48 samples). The biomass was classified in above-ground graminoids, forbs and dead matter, and below-ground roots and other below-ground organs. We used ANOVA to compare variables between treatments and seasons. Results: More than 40% of the total biomass and carbon stocks were located below-ground, mostly in roots. A high proportion of dead biomass (B4) was found in the above-ground material, probably due to low decomposition rates and consequent accumulation over the years. Although these grasslands do not experience water stress, we found significant evidence of resource re-allocation from below-ground organs to the above-ground biomass in the rainy season. Conclusions: We found more dead biomass in the rainy season, probably due to low decomposition rates, which can increase fire risk in these grasslands during the following dry season. These tropical wet grasslands stored high amounts of carbon (621 to 716 g C.m-2), mostly in the roots. Thus, policymakers should consider tropical grasslands as potential carbon stocks, since they are one of the most threatened and unprotected ecosystems in Brazil. © 2012 International Association for Vegetation Science.

Cinética de absorção de silício por cultivares de cana-de-açúcar e de arroz

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)