Eucalyptus Urophylla Seedlings Research Articles

Silicon attenuates nutritional disorder of phosphorus in seedlings of Eucalyptus grandis × Eucalyptus urophylla

BackgroundNutritional disorders of phosphorus (P), due to deficiency or toxicity, reduce the development of Eucalyptus spp. seedlings. Phosphorus deficiency often results in stunted growth and reduced vigor, while phosphorus toxicity can lead to nutrient imbalances and decreased physiological function. These sensitivities highlight the need for precise management of P levels in cultivation practices. The use of the beneficial element silicon (Si) has shown promising results under nutritional stress; nevertheless, comprehensive studies on its effects on Eucalyptus spp. seedlings are still emerging. To further elucidate the role of Si under varying P conditions, an experiment was conducted with clonal seedlings of a hybrid Eucalyptus spp. (Eucalyptus grandis × Eucalyptus urophylla, A207) in a soilless cultivation system. Seedlings were propagated using the minicutting method in vermiculite-filled tubes, followed by treatment with a nutrient solution at three P concentrations: a deficient dose (0.1 mM), an adequate dose (1.0 mM) and an excessive dose (10 mM), with and without the addition of Si (2mM). This study assessed P and Si concentration, nutritional efficiency, oxidative metabolism, photosynthetic parameters, and dry matter production.ResultsSi supply increased phenolic compounds production and reduced electrolyte leakage in seedlings provided with 0.1 mM of P. On the other hand, Si favored quantum efficiency of photosystem II as well as chlorophyll a content in seedlings supplemented with 10 mM of P. In general, Si attenuates P nutritional disorder by reducing the oxidative stress, favoring the non-enzymatic antioxidant system and photosynthetic parameters in seedlings of Eucalyptus grandis × Eucalyptus urophylla.ConclusionThe results of this study indicate that Eucalyptus grandis × Eucalyptus urophylla seedlings are sensitive to P deficiency and toxicity and Si has shown a beneficial effect, attenuating P nutritional disorder by reducing the oxidative stress, favoring the non-enzymatic antioxidant system and photosynthetic parameters.

EUCALYPTUS ‘GG 100’ RESPONSE TO SIMULATED DRIFT OF ORTHOSULFAMURON

Plant growth regulators and low doses of herbicides are used in some crops in order to achieve satisfactory yields. They can cause morphological or physiological changes in plants qualitatively or quantitatively, such as in the inhibition and delay of vegetative development, in the early maturation or in sugar accumulation. The application of these products through spraying aims to reach the target crop. However, some neighboring crops may be contaminated through drift. The present study aims to evaluate the effects of simulated drift of orthosulfamuron on the initial growth of Eucalyptus urophylla seedlings, clone GG 100. The experiment was installed in pots of 5 L capacity in a completely randomized design, with nine treatments and four replicates. The treatments consisted of the following nine increasing doses of orthosulfamuron ripener: 0; 1.19; 2.39; 4.78; 9.56; 19.12; 38.25; 76.5; and 127.5 g a.i. ha-1. The height of the eucalyptus plants were evaluated at 0, 14, 28, 42, and 63 days after application (DAA). At 63 DAA, in the end of the experiment, the stem diameter, leaf area, and the dry matter of leaves, stems, and roots were evaluated. In conclusion, there were no deleterious effects of the drift of orthosulfamuron up to the dose of 127.5 g a.i. ha-1 on the development and growth of E.urophylla seedlings, clone GG 100, up to 63 days after application.

Combined addition of bagasse and zeolite stabilizes potentially toxic elements in sewage sludge compost and improves Eucalyptus urophylla seedling growth

Potentially toxic elements (PTEs) including Cu, Zn, Pb, Cd and Ni in sewage sludge compost (SSC) are important obstacles to SSC forestry utilization. Synergistic fixation of bulking agent and adsorbent may shed new light on solving the problem for stabilization of PTEs in SSC before forestry disposal. The aim of this study was to investigate whether bulking agent (bagasse) + adsorbent (zeolite) can be integrated into forestry utilization processes of SSC. First, stabilization of PTEs in SSC were compared to those of composted bagasse + sewage sludge (BSC), zeolite + sewage sludge (ZSC) and bagasse + zeolite + sewage sludge (BZSC) after 60 days of composting. Subsequently, the long-term stability of PTEs in different composts-amended soil was monitored in a 2-year field trial on Eucalyptus urophylla forestland. Finally, a 12-month pot experiment was carried out to investigate their effects on the growth of Eucalyptus urophylla seedlings and PTEs absorption. Compared with SSC, addition of bagasse and zeolite significantly decreased total and extractable PTEs concentration and increased residual fractions in compost. In the field experiment, the total and extractable fraction concentrations of PTEs in topsoil after BZSC application were significantly lower than those after SSC and BSC application, and the status kept unchanged during the 2-year trial period. In the pot experiment, we further found that, compared with SSC, BSC and ZSC addition in the cultivated soil, the addition of BZSC promoted significantly greater growth and reduction in PTEs concentrations in Eucalyptus urophylla seedlings. Our results indicate that the combined addition of bagasse and zeolite can stabilize PTEs in SSC for an extended duration, improve plant growth, and therefore enhance the potential of sewage sludge compost utilization in forestry.

Cutting Preference of the Leaf-Heating ant atta sexdens by Seedlings of Eucalyptus urophlylla Submitted to Different Doses of Zinc

Leaf-cutting ants of the genus Atta, also known as leaf-cutting ants, are considered pests in forestry, in various agricultural crops, and also in pastures, causing great damage. Mineral elements are of great importance in increasing crop production and productivity and are involved in the defense mechanism and tolerance of plants to pest and disease attacks, when properly balanced in the soil. The objective of this study was to evaluate the cutting preference of leaf-cutting ants Atta sexdens for Eucalyptus urophylla seedlings submitted to different doses of zinc (Zn) cultivated in a dystrophic Cerrado Latosol. The doses of zinc provided were 0 (control) and 20 mg/dm³ plus 20 mg/L via foliar, in the form of zinc sulfate. The seedlings used were kept in a greenhouse for up to 80 days and then submitted to laboratory evaluation. The leaves of seedlings treated with different doses of zinc were offered in Petri dishes to three colonies of ants from artificial nests of A. sexdens in the laboratory with free choice between treatments. The percentage of leaf tissue cut and transported to the nests was evaluated for 20 minutes between different doses and colonies, and four sequential offers of leaves were made. Through the data obtained, it was observed that there was no preference for cutting the leaves of eucalyptus seedlings treated with different doses of zinc by the colonies of leaf-cutting ants Atta sexdens.

Effect of Application of Zinc on Seedlings of Eucalyptus urophylla

Eucalyptus represents a species with consolidated cultivation in the Cerrado and that has been cultivated in several states that cover this Biome. Thus, the objective was to evaluate the growth and development of Eucalyptus urophylla seedlings in response to soil and foliar zinc application in a Cerrado Red Latosol. Two experiments were set up in a completely randomized design, with five treatments and seven replications. The first experiment consisted of five doses of Zn, in the form of zinc sulfate for both experiments, 0; 2.5; 5; 10 and 20 mg/dm³ applied via soil and the second experiment consisted of five doses of Zn, 0; 2.5; 5; 10 and 20 mg/L applied via foliage plus an extra dose of 20 mg/dm³ of Zn applied via soil, this dose being necessary due to the low zinc content in the soil and which could compromise the initial development of seedlings that would receive applications via leaf. The experiments were carried out in a greenhouse and after 80 days of planting, the following were evaluated: stem diameter (neck), height, root length, number of leaves, shoot and root dry matter, total dry matter, of macro and micronutrients in leaves and gas exchange: internal carbon concentration, stomatal conductance, transpiration and net photosynthesis rate. Even though Eucalyptus urophylla seedlings did not show statistically significant differences, part of the evaluated variables showed a positive response to the application of zinc, analyzing the linear and quadratic regression graphs, mainly at doses of 10 and 20 mg/L and 10 and 20 g/dm³.

Genetic diversity and inoculation of plant-growth promoting diazotrophic bacteria for production of Eucalyptus urophylla seedlings

The study of diversity and the established relationship between plants and endophytic bacteria contribute significantly to the plant development. This study aimed to isolate, identify plant-growth promoting diazotrophic bacteria from Eucalyptus urophylla plants and evaluate the plant seedling response to inoculation with selected strains. The study was conducted from July 2017 to August 2018 set up in a greenhouse in a completely randomized experimental design with 17 treatments and 16 replicates, with 12 strains isolated from E. urophylla, four standard bacteria and one control (not inoculated with bacteria). Twelve strains were isolated from the eucalyptus rhizosphere using the N-free semisolid media and the 16 rRNA sequencing identified species closely related to Nitrospirillum amazonense, Stenotrophomonas maltophilia, Pantoea agglomerans, Herbaspirillum frisingense and Ideonella dechloratans. All strains were able to produce indol compounds and the presence of the nifH gene (nitrogen fixation) was demonstrated by PCR analysis. There was a significant effect of the strain inoculation on the height, diameter, root dry matter, root length, root area surface and volume of the seedling plant. The strains L1E, L4E - Azospirillum amazonense and L7E - Stenotrophomonas maltophilia presented high values variables of height, diameter, root dry matter, root length, root area surface and volume. Many of the bacterial strains were able to promote plant growth either by root morphology changes or biomass accumulation in root and shoots. Therefore, there is a biotechnological potential of these plant-growth promoting diazotrophic bacteria strains to be applied as inoculants to improve growth of eucalyptus seedlings. This fact opens new opportunities to establish forests with economically viable and environmentally sustainable technologies

Belowground interactions affect shoot growth in Eucalyptus urophylla under restrictive conditions

ABSTRACT Plant-plant interactions like competition or facilitation between seedlings can have profound implications on their establishment and posterior development. These interactions are variable and depend upon the presence of neighbouring plants and environmental factors. In this work, we studied the effects of the interaction by the roots of Eucalyptus urophylla seedlings from a population under various environmental stressful conditions: water deficit, nutrient deficit, low light, low temperature, and high temperature. To evaluate it, we measured some growth and morphological parameters. We demonstrated that shoot parameters such as the number of leaves, leaf area, and dry weight of the leaves were the most affected parameters due to the belowground plant-plant interaction under various environmental conditions. We did not find evidence for competition among the plants, especially under restrictive conditions. Therefore, the study corroborates the stress-gradient hypothesis, which states that plants’ differences under stressful conditions lead to facilitative interactions. It has implications for plant ecology and forestry techniques.

The physiological and molecular mechanisms of N transfer in Eucalyptus and Dalbergia odorifera intercropping systems using root proteomics

BackgroundThe mixing of Eucalyptus with N2-fixing trees species (NFTs) is a frequently successful and sustainable cropping practice. In this study, we evaluated nitrogen (N) transfer and conducted a proteomic analysis of the seedlings of Eucalyptus urophylla × E. grandis (Eucalyptus) and an NFT, Dalbergia (D.) odorifera, from intercropping and monocropping systems to elucidate the physiological effects and molecular mechanisms of N transfer in mixed Eucalyptus and D. odorifera systems.ResultsN transfer occurred from D. odorifera to Eucalyptus at a rate of 14.61% in the intercropping system, which increased N uptake and growth in Eucalyptus but inhibited growth in D. odorifera. There were 285 and 288 differentially expressed proteins by greater than 1.5-fold in Eucalyptus and D. odorifera roots with intercropping vs monoculture, respectively. Introduction of D. odorifera increased the stress resistance ability of Eucalyptus, while D. odorifera stress resistance was increased by increasing levels of jasmonic acid (JA). Additionally, the differentially expressed proteins of N metabolism, such as glutamine synthetase nodule isozyme (GS), were upregulated to enhance N competition in Eucalyptus. Importantly, more proteins were involved in synthetic pathways than in metabolic pathways in Eucalyptus because of the benefit of N transfer, and the two groups of N compound transporters were found in Eucalyptus; however, more functional proteins were involved in metabolic degradation in D. odorifera; specifically, the molecular mechanism of the transfer of N from D. odorifera to Eucalyptus was explained by proteomics.ConclusionsOur study suggests that N transfer occurred from D. odorifera to Eucalyptus and was affected by the variations in the differentially expressed proteins. We anticipate that these results can be verified in field experiments for the sustainable development of Eucalyptus plantations.

Influence of Arbuscular Mycorrhizae on the Development and Attack of Leaf-Cutting Ants in Clonal Seedlings of Eucalyptus urophylla x Eucalyptus camaldulensis

The present study aimed to evaluate the effect of the mycorrhizal association in the development and attack of leaf-cutting ants Atta sexdens (Linnaeus, 1758) in clonal seedlings of Eucalyptus urophylla x Eucalyptus camaldulensis hybrid. The treatments consisted of inoculated and uninoculated seedlings with 100 grams of sand containing spores from arbuscular mycorrhizal fungi (AMF) collected on native soil from four different areas of the amazon: native forest area (NF), permanent preservation area recovered to three years (PPA03), permanent preserved area degraded (PPAD) and permanent preservation area recovered to four years (PPA04). At 45 and 90 days after inoculation (d.a.i.), height, fresh and dry matter of shoot and root, root development, number of leaves, stem diameter and tolerance to leaf-cutting ants were evaluated. In the first group of plants (45 d.a.i.), mycorrhizal plants presented the higher root volume with the use of APP04, APP03 and NF all with 6.16 mm. For the second group of plants (90 d.a.i.), the highest root volume was also found on mycorrhizal plants with the soil of APP03 and control with 7.16 mm. For the attractiveness test of ants, 16 discs were taken from the non-inoculated seedlings. Regarding the disks of mycorrhizal seedlings with the soil of APP04, only 9 were taken. Although the use of AMF to stimulate plant resistance to attack by leaf-cutting ants is a new study, studies related to the influence of mychorrizas on plant development are quite common and the results presented in this study did not evidence the influence of mychorrizas on plant development. However, it was observed that the early inoculation of the seedlings can reduce the attractiveness of leaf-cutting ants by the seedlings of the hybrid Eucalyptus urophylla x Eucalyptus camaldulensis, already in the first 45 d.a.i of the seedlings and the inoculum used can interfere in this process.

Potencial uso da casca de café como constituinte de substrato para produção de mudas de espécies florestais

Na produção de mudas de espécies florestais há vários fatores que influenciam no seu crescimento. Dentre estes, um dos mais importantes é a composição do substrato. Nesse sentido, é essencial a seleção de bons constituintes que atendam a essa demanda. O objetivo deste trabalho foi avaliar o crescimento inicial de mudas de Eucalyptus urophylla, Peltophorum dubium e Eremanthus erythropappus, produzidas em diferentes formulações de substratos. Para cada espécie, foi instalado e conduzido um experimento, utilizando-se nas formulações os constituintes casca de arroz compostada, casca de café compostada, fibra de coco e substrato comercial. Os experimentos foram instalados em delineamento inteiramente casualizado (DIC), constituídos por oito tratamentos, cinco repetições e 20 mudas por parcela. Para avaliação da qualidade das mudas, aos 120 dias foram mensuradas as variáveis altura, diâmetro do coleto, peso de matéria seca da parte aérea, peso de matéria seca do sistema radicular e índice de qualidade de Dickson. Como análises qualitativas, foram avaliadas a facilidade de retirada das mudas do tubete e a agregação das raízes ao substrato. Os resultados encontrados após a avaliação atestaram que as mudas produzidas nos tratamentos formulados com casca de café compostada apresentaram valores superiores para a maioria das variáveis analisadas, quando comparado com as mudas produzidas nos tratamentos formulados com a casca de arroz e na testemunha. Para as três espécies, indica-se a utilização da proporção de 40% de casca de café compostada com 40% de substrato comercial e 20% de fibra de coco para composição do substrato.

Inflection point position as a potential diagnostic tool for the estimation of sulfur concentration in Eucalyptus seedlings

Specific techniques of spectral analysis to determine the nutritional stress caused by sulfur (S) may allow the early detection of its deficiency and directed supplementation in the corrective fertilization of plants. The aim of this study was to verify the alterations caused by S deficiency as well as to verify whether the spectral reflectance, that is, the inflection point position (IPP), obtained from a mini-spectrometer, can estimate S concentration and detect its deficiency in Eucalyptus urophylla seedlings. Seedlings were cultivated for 90 d in complete nutrient solution (without S omission) and with S omission. Sodium sulfate was used as a source of S. Sulfur deficiency caused changes in the morphological and physiological properties of the plants, which were reflected as changes in their leaf spectral properties. Visual symptoms of S deficiency, such as chloros is in new leaves and reductions in seedling growth started at 28 d after treatment application (DAT), reduction in height, diameter, and dry matter production were observed at 75 DAT. Nutritional analysis detected a reduction in leaf S concentrations and its deficiency in plants only at 45 DAT. However, at 30 DAT S deficiency changed seedling reflectance with S omission, shifting IPP to shorter wavelengths (± 700 ηm); that is, mini-spectrometer was able to detect the S deficiency in Eucalyptus plants. The IPP close to 700 ηm is a very sensitive indicator of S content and deficiency, demonstrating its great potential as a diagnostic tool to estimate leaf S content in Eucalyptus plants using a mini-spectrometer.

INFLUENCE OF THE REPLANTING AGE ON YIELD AND GROWTH OF EUCALYPT CLONAL STANDS

ABSTRACT The growth of an eucalypt plantation should be monitored to identify factors that influence its development, helping in the decision-making process, aiming to reduce productivity losses. Thus, the objective of the present study was to evaluate the influence of the age of replanting on the yield and growth of eucalypt stands. The experiment was conducted in an area of CENIBRA S.A. Company, and established in a commercial plantation in August 2011. The application of herbicide and the ant control were performed in total area before planting. Seedlings of Eucalyptus urophylla × Eucalyptus grandis clones in 3.0 × 2.5 m spacing were used. Limestone (1,500 kg ha-1) was applied in total area before planting and 100 g plant-1 of NPK fertilizer (06-30-06) was applied immediately after planting. Four months after the installation of the experiment, 300 kg ha-1 of NPK (06-10-29) was applied. Treatments consisted of four dates of seedling replanting (0, 20, 40 and 80 days after planting) without complementary fertilization, and two treatments (replanting 40 and 80 days after planting) with supplementary fertilization (100g plant-1 NPK 06-30-06). The individual volume of replanting trees was 46.6% lower than of non-replanted ones. Treatments with complementary planting fertilization did not differ (p > 0.05) by the T-test. It is concluded that the longer the time between planting and replanting, the smaller the individual volume of the replanting trees and that the complementary fertilization in seedlings replanted does not favor their growth.

First record of Myzus persicae (Sulzer, 1776) in Eucalyptus urophylla S. T. Blake

ABSTRACT: Insect pests are limiting factors to the expansion of Eucalyptus spp. plantations in Brazil. Aphids of the species Myzus persicae (Sulzer, 1776) (Hemiptera: Aphididae) are a key pests in different crops and may negatively affect the growth, development and survival of plants. This paper reports the first record of M. persicae in seedlings of Eucalyptus urophylla grown in a greenhouse in Diamantina, Minas Gerais state, Brazil. This finding suggests the implementation of an integrated management program for this aphid, in order to prevent it from becoming a pest in Eucalyptus .

REDUÇÃO FOLIAR EM MINIESTACAS E MICROESTACAS DE CLONES HÍBRIDOS DE Eucalyptus globulus

O objetivo deste estudo foi avaliar o efeito da redução foliar no enraizamento de dois tipos (apicais e intermediárias) de miniestacas e microestacas de quatro clones híbridos de Eucalyptus globulus. Foram realizadas avaliações quanto ao percentual de sobrevivência, raízes emitidas na extremidade inferior do tubete, enraizamento, altura, diâmetro do colo e massa seca da parte aérea e da raiz. Aos 90 dias de idade, pôde-se concluir que as estacas apicais sem e com redução foliar foram superiores às intermediárias e os clones se comportaram de maneira diferenciada em relação ao enraizamento das miniestacas e microestacas. A propagação vegetativa por estacas apicais sem redução foliar pode ser recomendada para a produção de mudas de Eucalyptus urophylla x E. globuluse de Eucalyptus grandis x E. globulus.

In vitro EVALUATION OF EUCALYPTUS ECTOMYCORRHIZAE ON SUBSTRATE WITH PHOSPHORUS DOSES FOR FUNGAL PRE-SELECTION

The benefit promoted by ectomycorrhizal depends on the interaction between symbionts and phosphorus (P) contents. Phosphorus effect on ectomycorrhizal formation and the effectiveness of these in promoting plant growth for fungal pre-selection were assessed under in vitro conditions. For P effect evaluation, Eucalyptus urophylla seedlings inoculated with four Pisolithus sp. isolates and others non-inoculated were grown on substrate containing 0.87, 1.16 and 1.72 mg P per plant. For evaluation of effectiveness and fungal pre-selection, other 30 isolates of Pisolithus sp., Pisolithus microcarpus ITA06 isolate, Amanita muscaria AM16 isolate, Scleroderma areolatum SC129 isolate were studied. D26 isolate promoted the highest plant heights for the three P doses, D51 at the lower dose and D72 at the intermediate dose. P doses did not influenced shoot fresh weight and fungal colonization. In the pre-selection of fungi, 14 isolates of Pisolithus sp., P. microcarpus ITA06 isolate and S. areolatum SC129isolate increased plant height and fresh weight. D82 isolate of Pisolithus sp. had effect singly on plant height while D17 and D58 on fresh weight. Of these, only D15, D17, D58 and ITA06 had typical ectomycorrhizae. The cultivation in vitro has shown adequate for pre-selection of ectomycorrhizal fungi. Colonization and benefits depend on species and isolate. D15, D17 and D58 of Pisolithus sp. and P. microcarpus isolate ITA06 are the most promising for nursery studies.

Effect of hog production wastewater in the development and quality of Eucalyptus urophylla substrate produced in urban solid waste

The objective of this study was to analyze the use of hog production wastewater in the production of seedlings of Eucalyptus urophylla, using a compound of municipal solid waste (SRSU) as substrate, and evaluating the effect of different proportions of ARS and of seedling ages in their morphological and nutritional quality. The experiment was conducted in a

Características morfofisiológicas associadas à qualidade de mudas de Eucalyptus urophylla produzidas em diferentes substratos

Neste estudo foram avaliados os efeitos de diferentes combinações de substratos sobre características morfológicas e fisiológicas relacionadas à qualidade de mudas de Eucalyptus urophylla. O experimento foi conduzido em um viveiro florestal a pleno sol, no qual foram produzidas mudas em tubetes de 54 cc e irrigadas por microaspersão. Empregou-se o delineamento experimental inteiramente casualizado com 12 tratamentos e quatro repetições. Os tratamentos foram baseados nas seguintes combinações de substratos: dois substratos comerciais (Vivatto Slim Plus e Mecplant), esterco bovino, pó de casca de coco, vermiculita e uma combinação utilizada por uma empresa do ramo florestal. Em todos os tratamentos foi adicionado Osmocote, fertilizante mineral de suprimento controlado de NPK. Foram avaliadas as seguintes características: Índice de Velocidade de Emergência (IVE), Emergência Total de Plântulas (EMER), Índice de Qualidade Dickson (IQD), Índice SPAD e Potencial de Regeneração de Raízes (PRR). Em geral, os melhores resultados foram obtidos nos tratamentos que continham esterco bovino e pó de casca de coco nas combinações de substratos. Para a qualificação das mudas, os valores de IQD mostraram-se, quase sempre, relacionados positivamente aos de PRR, exceto o substrato 100% da Vivatto Slim Plus, em que os maiores valores de IQD estiveram associados a valores mais baixos de PRR. A combinação de 40% de esterco bovino, 20% de pó de casca de coco e 40% de vermiculita resultou nas maiores médias do índice SPAD. A combinação de 70% de esterco bovino e 30% de pó de casca de coco proporcionou a produção de mudas com os maiores valores de PRR, as quais apresentaram qualidade superior à das demais combinações de substratos, com base nas características avaliadas.

Efficiency of phosphorus use in young plants of Eucalyptus urophylla S. T. Blake

The objective of this study is to select superior genotypes for efficiency of phosphorus use in seedlings of Eucalyptus urophylla, correlating them with initial height growth in the field, at age eight months. Acompletely randomized block design was used in the nursery, consisting of eight clones, three replicates and four plants per plot. The same design was used in the field, consisting of eight clones, four replicate blocks and nine plants per plot. Data being collected in the nursery at age 120 days included: phosphorus concentration in shoot (CPPA); phosphorus concentration in root (CPR); phosphorus content in shoot (CtPPA); phosphorus content in root (CtPR); total phosphorus content in seedling (CtPT); phosphorus use efficiency in shoot (EUP-PA); phosphorus use efficiency in root (EUP-R) and total phosphorus use efficiency (EUP-T). Analyses of variance showed significant genetic differences among clones for all traits and, given the high heritability values found, estimated genetic gains were generically very high. As regards predicted indirect genetic gain, it was noted that selection on nursery seedlings for all EUPs provided the highest values of indirect gain in height of field seedlings.

Uso de resíduos industriais na remediação de solo contaminado com cádmio e zinco

Este trabalho teve como objetivo avaliar a utilização de dois resíduos industriais na redução de disponibilidade de zinco e cádmio em solo contaminado. O experimento foi conduzido em casa de vegetação na Universidade Federal Rural do Rio de Janeiro por 225 dias, utilizando-se um substrato contaminado com zinco e cádmio, coletado no pátio de minério do Porto de Itaguaí, e próximo ao local de disposição de resíduo perigoso da Cia Mercantil e Industrial Ingá em Itaguaí, RJ. O substrato foi tratado com dois agentes inertizantes, assim descritos: um resíduo industrial com característica alcalina (Escória de Aciaria) em duas doses 4 e 6%, e outro com alto teor de óxido de ferro como adsorvente (Carepa de Laminação), em dose única de 1%. Após o plantio das mudas de Eucalyptus urophylla, foram feitas coletas do substrato em cada unidade experimental para determinação das frações biodisponíveis (extraído com MgCl2) e a não disponível. O substrato não tratado apresentava alto teor de cádmio e zinco na fração biodisponível. Os tratamentos causaram uma redução na disponibilidade desses elementos no solo, evidenciado na absorção diferenciada pelas plantas. Por causa da maior disponibilidade do cádmio e zinco no solo sem adição dos inertizantes, as plantas não resistiram aos altos teores desses elementos e morreram 30 dias após a implantação do experimento. A produção de massa seca foi influenciada positivamente pela aplicação dos agentes inertizantes, apresentando melhor resposta na maior dose de escória de aciaria. A maior dose também propiciou as menores concentrações dos elementos nas plantas, sem provocar deficiência do micronutriente zinco e mantendo o cádmio a níveis não tóxicos para as espécies de eucalipto. Apesar de apresentar menores concentrações de cádmio na dose de 6% de Escória de Aciaria,essa dose resultou na maior extração desse elemento pelas plantas.

Estresse hídrico em plantio de Eucalyptus grandis vs. Eucalyptus urophylla, em função do solo, substrato e manejo hídrico de viveiro

O objetivo deste trabalho foi avaliar em campo os níveis de estresse hídrico das mudas de Eucalyptus grandis vs. Eucalyptus urophylla selecionado para tolerância ao déficit hídrico, em função dos substratos, do manejo hídrico e dos solos. As mudas foram produzidas em dois viveiros distintos do Estado de São Paulo: com o substrato Plantmax estacas® (PLX) em Bofete (SP) e com a mistura em partes iguais de casca de arroz carbonizada e vermiculita (CAC), em Ibaté (SP). A partir dos 60 dias após a estaquia (DAE), durante a rustificação as mudas foram manejadas com cinco frequências de irrigação por subsuperfície: F1 - irrigado uma vez ao dia, F2 - irrigado duas vezes ao dia, F3 - irrigado três vezes ao dia, F4 - irrigado quatro vezes ao dia e FD - mantido em irrigação, restabelecendo a capacidade de campo até o plantio aos 90 DAE, em um solo argiloso e outro arenoso. Foram realizadas avaliações dos níveis de estresse (brando, moderado e severo), que afetaram a sobrevivência nos dois solos, por meio de censo aos 15 e aos 30 dias após o plantio. Com relação aos níveis de estresse avaliados, verificou-se pouca influência do substrato, porém onde ocorreu o PLX proporcionou menores percentuais de plantas afetadas. Independentemente do tipo de solo onde as mudas foram plantadas, os sintomas de estresse nas plantas, de modo geral, foram semelhantes. O manejo de viveiro não influenciou na sobrevivência das mudas, embora tenham ocorrido algumas diferenças estatísticas quando se usaram CAC e plantio no solo arenoso, porém sem tendência clara de comportamento. Os critérios relativos à implantação foram mais determinantes na sobrevivência das mudas no campo até os 30 dias após o plantio, indicando a necessidade de replantio.