Grandis Seedlings Research Articles

Análise técnica e econômica das etapas de produção de mudas de eucalipto

Com o objetivo de estimar os rendimentos operacionais e custos de produção de mudas de Eucalyptus grandis por meio de propagação vegetativa, conduziu-se o estudo em um viveiro de produção de mudas, pertencente a uma empresa florestal de grande porte, localizada no Estado de São Paulo. A análise técnica englobou um estudo de tempos e movimentos pelo método de tempo contínuo. A análise econômica ponderou todos os custos operacionais e de produção. Os resultados obtidos evidenciaram que as despesas com pessoal são as que mais oneram o custo da produção de mudas de eucalipto. Os coeficientes técnicos de cada etapa de produção devem ser administrados no sentido de estabelecer o valor ótimo da eficiência e do rendimento operacional, tornando-as economicamente viáveis.

UTILIZAÇÃO DO BIOSSÓLIDO DE CERVEJARIA COMO SUBSTRATO PARA PRODUÇÃO DE MUDAS DE EUCALIPTO: ANÁLISE DO DESENVOLVIMENTO INICIAL DAS MUDAS E ASPECTOS AMBIENTAIS

Este trabalho foi conduzido com o objetivo de avaliar o desenvolvimento de mudas de Eucalyptus grandis em substrato de lodo da estação de tratamento de efluente de indústria cervejeira. Os tratamentos consistiram de substratos proveniente de misturas de biossólidos com casca de arroz carbonizada, correspondentes a M1 - 80% de biossólido e 20% de casca de arroz carbonizada, M2 - 60% de biossólido e 40% de casca de arroz carbonizada, M3 - 50% de biossólido e 50% de casca de arroz carbonizada, M4 - 40% de biossólido e 60% de casca de arroz carbonizada e Testemunha composta de solo sem adição de lodo. A mistura que apresentou melhores resultados estatitiscamente foi a mistura M2 (60% lodo de esgoto + 40% casca de arroz carbonizada).

Effects of manganese-excess on CO2 assimilation, ribulose-1,5-bisphosphate carboxylase/oxygenase, carbohydrates and photosynthetic electron transport of leaves, and antioxidant systems of leaves and roots in Citrus grandis seedlings.

BackgroundVery little is known about the effects of manganese (Mn)-excess on citrus photosynthesis and antioxidant systems. Seedlings of sour pummelo (Citrus grandis) were irrigated for 17 weeks with nutrient solution containing 2 μM (control) or 500 μM (excess) MnSO4. The objective of this study were to understand the mechanisms by which Mn-excess leads to a decrease in CO2 assimilation and to test the hypothesis that Mn-induced changes in antioxidant systems differ between roots and leaves.ResultsMn-excess decreased CO2 assimilation and stomatal conductance, increased intercellular CO2 concentration, but did not affect chlorophyll (Chl) level. Both initial and total ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity in Mn-excess leaves decreased to a lesser extent than CO2 assimilation. Contents of glucose, fructose, starch and total nonstructural carbohydrates did not differ between Mn-excess leaves and controls, while sucrose content was higher in the former. Chl a fluorescence (OJIP) transients from Mn-excess leaves showed increased O-step and decreased P-step, accompanied by positive L- and K-bands. Mn-excess decreased maximum quantum yield of primary photochemistry (Fv/Fm) and total performance index (PItot,abs), but increased relative variable fluorescence at I-steps (VI) and energy dissipation. On a protein basis, Mn-excess leaves displayed higher activities of monodehydroascorbate reductase (MDAR), glutathione reductase (GR), superoxide dismutase (SOD), catalase (CAT) and guaiacol peroxidase (GPX) and contents of antioxidants, similar ascorbate peroxidase (APX) activities and lower dehydroascorbate reductase (DHAR) activities; while Mn-excess roots had similar or lower activities of antioxidant enzymes and contents of antioxidants. Mn-excess did not affect malondialdehyde (MDA) content of roots and leaves.ConclusionsMn-excess impaired the whole photosynthetic electron transport chain from the donor side of photosystem II (PSII) up to the reduction of end acceptors of photosystem I (PSI), thus limiting the production of reducing equivalents, and hence the rate of CO2 assimilation. Both the energy dissipation and the antioxidant systems were enhanced in Mn-excess leaves, while the antioxidant systems in Mn-excess roots were not up-regulated, but still remained high activity. The antioxidant systems in Mn-excess roots and leaves provided sufficient protection to them against oxidative damage.

First Report of Botryosphaeria dothidea Causing Canker and Shoot Blight of Eucalyptus in China.

Eucalyptus spp. are grown on approximately 2 million ha in China and is the most important genus in forest plantations worldwide. An outbreak of cankers and shoot blight was observed for the first time on Eucalyptus grandis in China during May of 2008. Symptoms included dieback of shoots and branches, lesions and canker formation on the stems, and clear or yellow-to-red exudates on stems and branches. Isolations were made from affected trees in Shilin County from May to July of 2008. Diseased samples were plated on potato dextrose agar (PDA) and incubated at 26°C. Fungal isolates developed copious, white, aerial mycelium that became dark gray after 5 to 6 days and formed black pycnidia after 14 days. Conidia were hyaline, aseptate, thin walled, fusiform, and measured 19 to 28 × 4 to 6 μm. Ascospores were hyaline, aseptate, and widest from the middle to upper third (17 to 28 × 6 to 13 μm). Identity was confirmed by analysis of the rDNA internal transcribed spacer region (ITSI-5.8S-ITS2) with primers ITS1 and ITS4. BLAST searches showed 99 to 100% identity with Botryosphaeria dothidea isolates from GenBank (Accession Nos. FJ358703 and EU080916). Representative sequences of B. dothidea from eucalyptus from China were deposited into GenBank (Accession Nos. FJ517657 and FJ517658). On the basis of morphological and molecular results, the fungus isolated from diseased eucalyptus wood was confirmed to be B. dothidea. Pathogenicity tests were conducted by stem inoculation of 10-month-old E. grandis seedlings. Two experiments were conducted using two inoculation techniques. In the first experiment, 2-mm-diameter actively growing mycelium plugs of B. dothidea were applied to 2-mm-long bark wounds on the middle point of the stems, and control seedlings were inoculated with sterile PDA plugs in a similar fashion as above. Inoculated and control seedlings were inoculated in a greenhouse and watered as needed. In the second experiment, segments of branches (averaging 18 mm in diameter and 30 cm long) were inoculated with 5-mm-diameter plugs of actively growing mycelium. Control segments of branches were inoculated as previously described. The branches were incubated at 26°C in moist chambers. There were five replicate seedlings per inoculation technique. After 20 days, all E. grandis seedlings showed leaf wilting, Dark, vascular stem tissue was observed. Symptoms were more abundant on the segment of branches. After 6 days, vascular necroses that developed on the inoculated plants were 5.2 ± 1.2 cm. B. dothidea was reisolated from all inoculated symptomatic tissue; no symptoms were visible in the control seedlings and no fungus was isolated from them. These results confirm previous reports of B. dothidea causing canker and dieback symptoms of Eucalyptus species in Australia (2), the United States (1), and South Africa (3). To our knowledge, this is the first report of B. dothidea causing canker disease on eucalyptus in China.

Estabelecimento a campo de mudas de <i>Eucalyptus grandis </i>micorrizadas com <i>Pisolithus microcarpus</i> (UFSC Pt 116) em solo arenoso.

O objetivo deste trabalho foi avaliar a sobrevivência e o crescimento inicial de mudas de eucalipto micorrizadas com o fungo ectomicorrízico Pisolithus microcarpus (UFSC Pt 116), após o transplante para uma área sujeita à arenização no município de São Francisco de Assis, RS. A área foi dividida em quatro blocos, cada qual com quatro tratamentos (turfa fértil com e sem fungo, Neossolo Quartzarênico com e sem fungo). Cada parcela foi composta por 16 mudas dispostas em quatro linhas no espaçamento de 1,5 m x 1,5 m, totalizando em cada bloco 64 mudas. Aos 90 dias após o plantio no campo, as mudas de eucalipto produzidas no substrato turfa fértil com fungo, apresentaram uma taxa de sobrevivência de 100%, enquanto que as produzidas em turfa fértil sem fungo, a taxa de sobrevivência foi de 92%. As mudas produzidas no Neossolo Quartzarênico com e sem fungo tiveram uma taxa de sobrevivência variando em torno de 98 e 89% respectivamente. As mudas produzidas com turfa e fungo apresentaram diferenças significativas no crescimento em altura, e diâmetro do caule. Conclui-se que mudas de Eucalyptus grandis produzidas em substrato turfa fértil e micorrizadas com o isolado Pisolithus microcarpus (UFSC Pt 116), conseguem manter bom estabelecimento e desenvolvimento no campo.

Período de permanência de mudas de Eucalyptus grandis em viveiro baseado em parâmetros morfológicos

Mesmo tendo avançado nas técnicas de produção de mudas, ainda existem muitos problemas a serem solucionados, principalmente no que se refere à expedição de mudas da casa de vegetação. Assim, este trabalho teve como objetivo verificar a variação espacial de mudas de Eucalyptus grandis ao longo do tempo, para estabelecer formas de expedição das mudas da casa de vegetação no viveiro florestal da Universidade Federal de Santa Maria, RS. Para tanto, foi instalado um experimento, em que se realizaram quatro avaliações com intervalo de 15 dias, e cada repetição foi dividida em parcelas para determinar a melhor forma de saída das mudas da casa de vegetação. Foi verificado maior homogeneidade entre as parcelas aos 100 dias após a emergência (DAE), dividindo-se a bandeja em Bordadura x Centro, Frente x Centro x Fundo e quadrantes e aos 115 DAE, para a simulação Direita x Centro x Esquerda, com a porção central apresentando sempre os melhores resultados. Houve variabilidade significativa entre posições dentro da bandeja e ao longo do tempo nas diferentes simulações de parcelas, e aos 100 DAE obteve-se a homogeneidade em todas as variáveis nas parcelas simuladas, como Frente x Centro x Fundo, podendo a porção central ser liberada aos 100 DAE, enquanto as demais porções tiveram de aguardar até os 115 DAE.

Taxa fotossintética líquida de Eucalyptus citriodora Hook e E. grandis W. Hill em resposta à diferentes níveis de água no solo e associação com Brachiaria brizantha Stapf

The effects of Brachiaria brizantha (Poaceae) interference on the net photosynthetic rate (A) of Eucalyptus citriodora and E. grandis (Myrtaceae) seedlings cultivated in soils with three levels of water under greenhouse conditions are provided. Treatments were arranged in a factorial design, with four repetitions 2x3x4: two species of eucalyptus ( E. citriodora and E. grandis ), three levels of water (20, 23 and 26%), and four populations of B. brizantha (0, 1, 2 and 3 plants per vase). Water level in the vases was maintained constant until the evaluation of final experiment 70 days after transplant of seedlings. Moisture control was done by a microtensiometer and daily weighting of vases with three replenishments of evapotranspired water. Measurements were executed with an infrared gas analyser (IRGA). In spite of any water level in the soil, B. brizantha demonstrated its competitiveness for E. citriodora and E. grandis initial growing, by A reduction. Upper third part of leaves of E. citriodora or E. grandis seedlings presented higher A than mean and lower third section, independently of B. brizantha population and water level in the soil

Mixed-species plantations of Acacia mangium and Eucalyptus grandis in Brazil : 1. Growth dynamics and aboveground net primary production

Abstract Nitrogen fertilizer inputs increased sharply over the last decade in Brazilian eucalypt plantations. Due to the economic and potential environmental cost of fertilizers, mixed plantations with N-fixing species might be an attractive option to improve the long-term soil N status. A randomized block design was set up in southern Brazil, including a replacement series and an additive series design, as well as a nitrogen fertilization treatment. The development of mono-specific stands of Eucalyptus grandis (0A:100E) and Acacia mangium (100A:0E) was compared with mixed plantations in proportions of 1:1 (50A:50E), and other stands with different densities of acacia for the same density of eucalypts. The objective was to assess the effect of inter-specific interactions on the early development of the two species. Aboveground biomass was measured 6, 12, 18 and 30 months after planting, sampling 6–10 trees of each species per treatment at each age, and allometric equations were established in 0A:100E, 100A:0E, 50A:50E and 50A:100E. The height and basal area of E. grandis seedlings were enhanced by 12% and 30%, respectively by N fertilization at age 1 year. Inter-specific competition led to a stratified canopy, with suppression in acacia growth earlier for basal area than for height. The mean number of stems per acacia tree at 36 months after planting was significantly higher in pure stands (3.7), than in 50A:50E (2.7) and in the additive series (between 1.6 and 1.8). H / D ratios were highly sensitive to inter-tree competition for the two species. The suppressed acacia understorey in mixed-species stands did not influence biomass production and partitioning within eucalypts. This pattern led to biomass accumulation combining the two species in 50A:100E that was about 10% higher than in 0A:100E, from age 12 months onwards. Aboveground net primary production (ANPP) amounted to 25 Mg ha −1 and 37 Mg ha −1 from age 18 to 30 months in 100A:0E and 0A:100E, respectively. Acacia ANPP in 50A:100E amounted to 2 Mg ha −1 over the same period, as a result of substantial inter-specific competition. An increment in biomass production in these very fast-growing eucalypt plantations was achieved introducing acacia as an understorey and not in the 50A:50E design, as observed in other studies.

Qualidade de mudas de eucalipto produzidas sob diferentes lâminas de irrigação e dois tipos de substrato

Este trabalho teve por objetivo avaliar lâminas de irrigação na produção de mudas de Eucalyptus grandis, produzidas em dois substratos comerciais à base de cascas de árvores (CPV e CATV). O experimento foi conduzido na Camará - Mudas Florestais, em Ibaté, SP, na estação inverno/primavera/2003, constituindo-se de um delineamento de blocos ao acaso com quatro repetições, sendo cinco lâminas de irrigação diárias (6, 8, 10, 12 e 14 mm), aplicadas através de uma barra de irrigação em diferentes horários (10, 13 e 16 h). Aos 108 dias após a aplicação foram realizadas avaliações da altura de parte aérea, diâmetro de colo, relação altura da parte aérea/diâmetro de colo, número de pares de folhas, matéria seca da parte aérea e das raízes e área foliar. Com relação às características morfológicas, verificou-se a influência das lâminas em todas as variáveis. Dessa maneira, concluiu-se que as lâminas de irrigação de 12 e de 14 mm dia-1 foram as que mais contribuíram para o desenvolvimento das mudas, com qualidade ótima aos 108 dias após a semeadura.

Measuring water stress in Eucalyptus grandis Hill ex Maiden seedlings planted into pots

Abstract A pot trial incorporating various watering regimes was initiated to assess: 1) water stress in Eucalyptus grandis seedlings, and 2) the efficacy of different types of research equipment in quantifying these levels of water stress for applied research. There were two dry soil treatments differing in terms of seedling root plug moisture at transplanting, dry (DD) and wet (WD), respectively, and three treatments consisting of well watered seedlings transplanted into wet soil (WWD, WWW and control). Treatment WWW was re-watered when seedlings were water stressed. The control was maintained at field capacity for the entire trial period. Seedling physiology was assessed by shoot water potential, stomatal conductance and chlorophyll fluorescence. Seedlings with dry root plugs, planted into dry soil were dead one to two days after planting. A wet root plug at the time of transplanting increased seedling shoot water potential and survival for up to three days in dry soil. Planting into wet soil increased shoot water potential for the duration of the trial and was also associated with new root growth. This study indicated that both the pressure chamber and the porometer provided simple and easy to interpret measures of water stress in E. grandis seedlings. Measurements of chlorophyll fluorescence did not significantly reflect treatment effects.

Nutrição mineral de mudas de eucalipto produzidas sob diferentes lâminas de irrigação e substratos

Este trabalho teve como objetivo avaliar os efeitos das lâminas brutas de irrigação na concentração de nutrientes de mudas de Eucalyptus grandis, produzidas em diferentes substratos. O experimento foi realizado na Camará - Mudas Florestais, em Ibaté, SP, e constituiu-se de um fatorial 5 x 4, sendo cinco lâminas brutas de irrigação diárias (6, 8, 10, 12 e 14 mm), aplicadas em diferentes horários (10, 13 e 16 h), e quatro substratos (FB - fibra de coco; CPV - casca de pinus e vermiculita; CATV - casca de pinus, carvão, turfa e vermiculita; e um MIX - 70 % de CPV e 30 % de FB). Foram determinadas os conteúdos dos nutrientes na parte aérea e no sistema radicular das mudas. Os resultados indicaram que houve influência das lâminas de irrigação e dos substratos no conteúdo dos nutrientes das mudas com maior acúmulo dos mesmos à medida que o fornecimento de água foi maior. As plantas crescidas nos substratos FB e CPV registraram os maiores acúmulos de nutrientes. CPV foi o melhor em se tratando do acúmulo dos macronutrientes nas raízes e também, juntamente com FB, o melhor para o acúmulo dos micronutrientes nas raízes e na parte aérea. Não houve influência dos substratos no acúmulo dos macronutrientes na parte aérea, porém houve das lâminas de irrigação.

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

Este trabalho teve por objetivo estudar a viabilidade do uso de águas residuárias provenientes de um sistema biológico de tratamento de esgotos domésticos como alternativa à fertirrigação convencional de viveiros florestais, visando à produção de mudas de Eucalyptus grandis via subirrigação contínua. As variáveis avaliadas foram: altura, diâmetro do coleto, peso da matéria seca da parte aérea e da raiz, área foliar, razão raiz/parte aérea e concentração nutricional foliar. O desenvolvimento das plantas, em geral, foi superior no tratamento convencional com adubos minerais. A razão raiz/parte aérea foi favorecida no tratamento com água residuária. Os resultados indicaram que a água residuária pode ser utilizada na fertirrigação de viveiros para a produção do Eucalyptus grandis, pois todas as plantas cresceram, sem deficiência ou toxidez aparente. Entretanto, constatou-se que essas mudas necessitavam de um maior tempo no viveiro, em comparação com as produzidas com fertilizantes minerais.

Temperature effects on wood anatomy, wood density, photosynthesis and biomass partitioning of Eucalyptus grandis seedlings

Wood density, a gross measure of wood mass relative to wood volume, is important in our understanding of stem volume growth, carbon sequestration and leaf water supply. Disproportionate changes in the ratio of wood mass to volume may occur at the level of the whole stem or the individual cell. In general, there is a positive relationship between temperature and wood density of eucalypts, although this relationship has broken down in recent years with wood density decreasing as global temperatures have risen. To determine the anatomical causes of the effects of temperature on wood density, Eucalyptus grandis W. Hill ex Maiden seedlings were grown in controlled-environment cabinets at constant temperatures from 10 to 35 degrees C. The 20% increase in wood density of E. grandis seedlings grown at the higher temperatures was variously related to a 40% reduction in lumen area of xylem vessels, a 10% reduction in the lumen area of fiber cells and a 10% increase in fiber cell wall thickness. The changes in cell wall characteristics could be considered analogous to changes in carbon supply. Lumen area of fiber cells declined because of reduced fiber cell expansion and increased fiber cell wall thickening. Fiber cell wall thickness was positively related to canopy CO2 assimilation rate (Ac), which increased 26-fold because of a 24-fold increase in leaf area and a doubling in leaf CO2 assimilation rate from minima at 10 and 35 degrees C to maxima at 25 and 30 degrees C. Increased Ac increased seedling volume, biomass and wood density; but increased wood density was also related to a shift in partitioning of seedling biomass from roots to stems as temperature increased.

Modeling Grouped Survival Data with Time-Dependent Covariates

In this article, proportional hazards and logistic models for grouped survival data were extended to incorporate time-dependent covariates. The extension was motivated by a forestry experiment designed to compare five different water stresses in Eucalyptus grandis seedlings. The response was the seedling lifetime. The data set was grouped since there were just three occasions in which the seedlings was visited by the researcher. In each of these occasions also the shoot height was measured and therefore it is a time-dependent covariate. Both extended models were used in this example, and the results were very similar.

Effects of leaf and branch removal on carbon assimilation and stem wood density of Eucalyptus grandis seedlings

The rate of leaf CO2 assimilation (Al) and leaf area determine the rate of canopy CO2 assimilation (Ac) can be thought proportional to assimilate supply for growth and structural requirements of plants. Partitioning of biomass within plants and anatomy of cells within stems can determine how assimilate supply affects both stem growth and wood density. We examined the response of stem growth and wood density to reduced assimilate supply by pruning leaf area. Removing 42% of the leaf area of Eucalyptus grandis Hill ex Maiden seedlings did not stimulate leaf-level photosynthesis (Al) or stomatal conductance, contrary to some previous studies. Canopy-level photosynthesis (Ac) was reduced by 41% immediately after pruning but due almost solely to continued production of leaves, and was only 21% lower 3 weeks later. Pruning consequently reduced seedling biomass by 24% and stem biomass by 18%. These reductions in biomass were correlated with reduced Ac. Pruning had no effect on stem height or diameter and reduced wood density to 338 kg m−3 compared to 366 kg m−3 in control seedlings. The lower wood density in pruned seedlings was associated with a 10% reduction in the thickness of fibre cell walls, and as fibre cell diameter was invariant to pruning, this resulted in smaller lumen diameters. These anatomical changes increased the ratio of cross-sectional area of lumen to area cell wall material within the wood. The results suggest changes to wood density following pruning of young eucalypt trees may be independent of tree volume and of longer duration.

Propriedades químicas do solo e nutrição do eucalipto em função da aplicação de lodo de esgoto

A aplicação do lodo de esgoto em plantações florestais é uma das alternativas para resolver o problema da disposição final desse resíduo. O objetivo deste trabalho foi avaliar se a aplicação de biossólido melhora a fertilidade do solo e o estado nutricional de mudas de Eucalyptus grandis. O experimento foi montado em colunas de PVC de 20 cm de diâmetro, com nove tratamentos (testemunha, adubação mineral, doses crescentes de biossólido variando de 10 a 160 t ha-1) e quatro repetições. O experimento foi realizado durante 12 meses após o plantio das mudas. O biossólido influenciou mais a acidez do que outros atributos químicos do solo. Os teores de N, P e S nas folhas correlacionaram-se com a CTC e com o teor de C orgânico do solo, tendo essas variáveis apresentado valores significativamente mais elevados nas doses de 80 e 160 t ha-1. Observou-se diminuição da matéria orgânica do solo nas doses de 10 a 40 t ha-1. O biossólido alcalino diminui a acidez do solo e melhora sua fertilidade, aumentando a disponibilidade da maioria dos nutrientes.

Why does phosphorus limitation increase wood density in Eucalyptus grandis seedlings?

Wood density influences both the physiological function and economic value of tree stems. We examined the relationship between phosphorus (P) supply and stem wood density of Eucalyptus grandis Hill ex Maiden seedlings grown with varying soil P additions and determined how changes in wood anatomy and biomass partitioning affect the relationship. Plant height, stem diameter and total biomass increased by 400-500% with increasing P supply. Stem wood density decreased sharply from 520 to 380 kg m(-3) as P supply increased to 70 mg P kg(soil) (-1). Further increases in P supply to 1000 mg P kg(soil) (-1) had no effect on wood density. The increase in wood density at low soil P supply arose principally from enhanced secondary wall thickening of stem fiber cells. Cell wall thickness increased from 3.6 to 4.5 microm as soil P supply decreased. Because fiber cell diameter was independent of soil P (12 microm +/- 0.3), the proportion of the stem occupied by cell wall material increased as P supply declined. The enhanced secondary wall thickening of stem fiber cells at low P supply was not associated with changes in whole-plant biomass partitioning. Instead, low P supply appeared to alter biomass partitioning within the stem in favor of secondary wall thickening. Thus, increased wood density in E. grandis seedlings grown at low P soil supply was associated with inhibited stem cambial activity, resulting in an increased proportion of photoassimilates available for secondary wall thickening of fiber cells.

Leaf inorganic phosphorus as a potential indicator of phosphorus status, photosynthesis and growth of Eucalyptus grandis seedlings

Abstract In eucalypts the reduction in CO2 assimilation and total leaf area at low phosphorus (P) supply is not associated with lower leaf total P concentrations. We tested the hypothesis that the leaf concentration of inorganic phosphorus ([Pi]) may be a better indicator of P nutrition status in Eucalyptus grandis W. Hill ex Maiden by growing seedlings in P deficient soil supplemented with P supplies ranging from 3 to1000 mg kg−1. Height, biomass accumulation, gas exchange, chlorophyll fluorescence and concentrations of total P ([Pt]), organic P ([Po]) and [Pi] of the last fully expanded leaves were measured when harvested at 19 weeks. All parameters of growth increased with larger applications of soil P with most becoming saturated at additions of 500 mg P kg−1 soil. Soil P supply had larger effects on biomass and canopy leaf area, by both increased in leaf initiation and expansion, than on CO2 assimilation (A). Leaf [Pt] and [Po] concentrations were largely invariant to soil P supply and were not correlated with any of the measured growth and photosynthetic parameters. By contrast, leaf [Pi] increased from 171 to 398 mg kg−1 with increasing soil P supply. Furthermore, number of leaves, total leaf area and seedling biomass increased exponentially with leaf [Pi], while individual leaf area and A increased linearly with leaf [Pi], and quantum yield of photosystem II similarly increased, and non-photochemical quenching decreased, with increasing leaf [Pi]. The response of A to internal CO2 concentration (Ci) indicated that at lower P supplies A became increasingly restricted by limitations associated with Rubisco and RuBP regeneration. Stomatal limitation may in part be masking the full effect of P supply on A as Ci declined with either increasing soil P or leaf [Pi] supply. We conclude that leaf [Pi] was a potentially better indicator than [Pt] or [Po] for correlating the effects of soil P supply on growth and photosynthesis of E. grandis. Furthermore, as A achieved at saturating Ca increased with increasing P supply leaf [Pi], these findings suggest that a greatly increased rate of canopy assimilation could be achieved at higher P supply in response to the expected increase in global CO2 levels.

Imazapyr root exudation from eucalypt seedlings cultivated in nutritive solution

Imazapyr has been used in Brazilian eucalypt cultivation for the maintenance of clearings and coppicing control in areas undergoing stand reform. However, inquiries have been made as to the final fate of the molecule. Imazapyr root exudation in eucalypt plants was evaluated through a bioassay under greenhouse conditions, by applying different herbicide doses (0.000, 0.375, 0.750, 1.125, and 1.500 kg ha-1 a.i.) on Eucalyptus grandis seedlings derived from vegetative propagation, hydroponically cultivated in 2.500 ml vases. Forty-day-old seedlings of the same clone were used as bioindicators, transplanted to the vases two days after herbicide application. After a period of 13 days of coexistence, the sprayed plants were removed and discarded; ten days later, the visual symptoms of toxicity were evaluated and the total dry biomass (aerial part and roots) of the bioindicators were determined. The lowest herbicide dose (0.375 kg ha-1 a.i.) affected the total biomass and growth, being most evident in the aerial part, with larger I50 for root dry biomass. The E. grandis seedlings exuded imazapyr, and/or its metabolites, in concentrations capable of affecting the growth of plants of the same species.

Diagnóstico de deficiência de macronutrientes em mudas de teca

O trabalho teve como objetivo caracterizar a sintomatologia visual e o crescimento e teor de nutrientes na parte aérea e no sistema radicular de mudas de Tectona grandis, transferidas para soluções nutritivas com exclusão de macronutrientes. As mudas foram produzidas em substrato comercial, onde permaneceram por quatro meses, sendo depois transferidas para rizotrons, em que foram submetidas, por 30 dias, à solução nutritiva completa e soluções preparadas com a supressão de N, P, K, Ca, Mg e S. O delineamento foi inteiramente casualizado, com cinco repetições. As soluções foram renovadas a cada duas semanas e o volume, completado diariamente com água desionizada, mantendo-se o pH em torno de 5,5 + 0,5. O desenvolvimento inicial de mudas de Tectona grandis foi afetado pela omissão de todos os macronutrientes, sendo os sintomas condizentes com o padrão apresentado pela maioria das culturas. Os danos mais intensos e imediatos foram observados na ausência de N e Ca, causando, inclusive, apodrecimento das raízes secundárias e paralisação na emissão de novas raízes. Os teores nutricionais da parte aérea e sistema radicular das mudas submetidas à solução completa foram, respectivamente: 38,0 e 26,9 g kg-1 de N; 8,5 e 4,0 g kg-1 de P; 22,8 e 13,1 g kg-1 de K; 2,3 e 3,7 g kg-1 de S; 10,5 e 2,0 g kg-1 de Ca; 3,0 e 1,7 g kg-1 de Mg; 175,2 mg kg-1 e 3,6 g kg-1 de Fe; 23,1 e 48,1 mg kg-1 de Zn; 4,3 e 17,8 mg kg-1 de Cu; e 142,5 e 389,8 mg kg-1 de Mn.