Leonardo David Tuffi Santos

Leaf anatomy and morphometry in three eucalypt clones treated with glyphosate

This work aimed to evaluate the effects of simulated drift of glyphosate on the morphoanatomy of three eucalypt clones and to correlate the intoxication symptoms on a microscopic scale with those observed in this visual analysis. The effects of glyphosate drift were proportional to the five doses tested, with Eucalyptus urophylla being more tolerant to the herbicide than E. grandis and urograndis hybrid. The symptoms of intoxication which were similar for the different clones at 7 and 15 days after application were characterized by leaf wilting, chlorosis and curling and, at the highest rates, by necrosis, leaf senescence and death. Anatomically glyphosate doses higher than 86.4 g.ha-1 caused cellular plasmolysis, hypertrophy and hyperplasia, formation of the cicatrization tissue and dead cells on the adaxial epidermis. The spongy parenchyma had a decrease, and the palisade parenchyma and leaf blade thickness had an increase. The increased thickness in leaf blade and palisade parenchyma may be related to the plant response to glyphosate action, as a form of recovering the photosynthetically active area reduced by necroses and leaf senescence caused by the herbicide.

Photosynthetic efficiency and water use in eucalyptus plants sprayed with glyphosate

Objetivou-se com este trabalho avaliar a eficiencia fotossintetica e o uso da agua por plantas de clones de eucalipto submetidas ao herbicida glyphosate. O experimento foi realizado em esquema fatorial 4 x 5, com quatro clones de eucalipto (57, 386, 1203 e 1213) e quatro doses de glyphosate (43,2; 86,2; 129,6; e 172,8 g ha-1) e uma testemunha sem herbicida, considerada dose zero, com quatro repeticoes. Aos 7, 14, 21 e 28 dias apos aplicacao do herbicida (DAA) foi avaliada a intoxicacao das plantas, e aos 7 e 21 DAA, o fluxo de gases pelos estomatos (U - mmol s-1), a atividade fotossintetica (A - mmol m-2 s-1), a condutância estomatica (Gs - mol m-1 s-1), a transpiracao (E - mol H2O m-2 s-1) e a eficiencia do uso da agua (QUE - mol CO2 mol H2O-1). Aos 50 DAA, as plantas de eucalipto foram coletadas e colocadas em estufa de ventilacao forcada a 70 oC ate atingirem massa constante. Aos 21 DAA, o clone 1203 comportou-se como mais sensivel ao herbicida. Nao houve diferenca entre clones para as variaveis fisiologicas avaliadas. Aos 21 DAA constatou-se que, com o incremento da dose de glyphosate, houve reducao na condutância estomatica, na taxa de fluxo de gases pelos estomatos, na taxa fotossintetica e na eficiencia do uso da agua. Plantas dos clones 1213 e 1203 apresentaram maior acumulo de massa seca. O aumento da dose do glyphosate promoveu menor acumulo de massa seca das plantas de eucalipto. O glyphosate afetou negativamente o crescimento e a eficiencia fotossintetica e de uso da agua dos clones estudados.

Foliar anatomy and histochemistry in seven species of Eucalyptus

This work aimed to describe the foliar anatomy of seven species of Eucalyptus, emphasizing the characterization of secretory structures and the chemical nature of the compounds secreted and /or present in the leaves. Anatomical characterization and histochemical evaluation to determine the nature and localization of the secondary compounds were carried out in fully expanded leaves, according to standard methodology. Anatomical differences were verified among the species studied, especially in E. pyrocarpa. Sub-epidermal cavities were the only secretory structures found in the seven species studied, with higher density in E. pellita and lower in E. pilularis. The following compounds were histochemically detected: lipophilic compounds, specifically lipids of the essential or resin-oil type and sesquiterpene lactones found in the lumen of the cavities of the seven species; and hydrophilic compounds, of the phenolic compound type found in the mesophyll of all the species studied and on the epidermis of some of them. The results confirmed the complexity of the product secreted by the cavities, stressing the homogeneous histochemistry nature of these compounds among the species. However, the phenolic compounds results may be an indication of important variations in adaptations and ecological relations, since they show differences among the species.

Glyphosate reduces urediniospore development and Puccinia psidii disease severity on Eucalyptus grandis

BACKGROUND Recent studies have shown the effects of glyphosate drift on decreasing rust intensity on Eucalyptus grandis plants. However, the effects of the herbicide on Puccinia psidii initial development are unknown. In this study the systemic action of glyphosate on rust severity was evaluated on Eucalyptus plants maintained under greenhouse conditions. Urediniospore germination and apressorium formation on detached leaves and on water agar medium, previously treated with glyphosate, were also evaluated. RESULTS Rust severity and the number of urediniospores per leaf area were significantly reduced with increasing glyphosate doses, even on branches not directly treated with the herbicide, indicating a systemic effect of glyphosate on pathogen development. Similarly, higher glyphosate doses also reduced germination and apressorium formation on detached Eucalyptus leaves, regardless of the direct application of the product on the leaf limb or on the petiole base. Puccinia psidii urediniospore germination in water agar medium also decreased with increasing herbicide doses. CONCLUSIONS Reductions in germination and apressorium formation of P. psidii urediniospores with increasing glyphosate dose indicate that a lower severity and intensity of the disease may perhaps be due to blockage of the shikimic acid pathway in the fungal metabolic system.

Germinação de sementes aéreas e subterrâneas de Commelina benghalensis

O conhecimento dos mecanismos de reproducao de uma especie de planta daninha, principalmente em relacao a dormencia e germinacao de suas sementes, e de grande importância na determinacao do metodo e da epoca ideal de seu controle. Com o objetivo de avaliar a germinacao de sementes aereas e subterrâneas de Commelina benghalensis, plantas desta especie foram cultivadas em vasos, em casa de vegetacao, nas condicoes de Vicosa, Estado de Minas Gerais, Brasil. Semente subterrânea grande (SSG) e semente aerea pequena (SAP) apresentaram o maior e o menor peso (8,81 e 1,90 mg/semente, respectivamente). Semente aerea grande (SAG) e semente subterrânea pequena (SSP) apresentaram pesos intermediarios (3,65 e 3,51 mg/semente, respectivamente), porem semelhantes entre si. A data de coleta das sementes aereas influenciou seu peso, observando-se, nas condicoes do experimento e no intervalo considerado (setembro a dezembro), maior peso de semente na primeira coleta (24/9/1999). A germinacao das sementes aereas nao foi influenciada pelo tempo de armazenamento. Sementes aereas pequenas germinaram melhor a 20-35 oC, e as grandes, a 25 oC. A germinacao de sementes aereas recem-colhidas variou de 7,50% em SAP a 21,67% em SAG/E (semente aerea grande com envoltorio). O armazenamento por quatro meses aumentou a porcentagem de germinacao de SAG e nao alterou a de SAG/E e SAP. Sementes subterrâneas pequenas e grandes armazenadas por tres meses apresentaram 32,5 e 92,5% de germinacao, respectivamente. O aumento do tempo de armazenamento de tres para seis meses diminuiu a porcentagem de germinacao de SSG e SSP. O calor seco aumentou a porcentagem de germinacao de SAG/E e SSP, nao alterou a de SAG e SAP e diminuiu a de SSG. O grau de dormencia diferiu muito entre os quatro tipos de sementes. A producao de sementes polimorficas com grandes diferencas no grau de dormencia permite que C. benghalensis germine e se estabeleca nos mais diversificados ambientes e epocas do ano, o que dificulta o manejo desta especie daninha.

CRESCIMENTO INICIAL DE EUCALIPTO E ACÁCIA, EM DIFERENTES ARRANJOS DE INTEGRAÇÃO LAVOURA-PECUÁRIA-FLORESTA

The objective was to evaluate initial growth of clonal Eucalyptus, hybrid Eucalyptus grandis x E. urophylla and Acacia (Acacia mangium) trees in alternate and not alternate rows of trees, intercropped with forage (crop-livestock-forest integration - CLFI) and monoculture. The design was a randomized complete block design with four replications, three arboreal arrangements consisting of eucalyptus, acacia + eucalyptus, acacia, all planted in crop-livestock-forest integration and two monoculture controls (Eucalyptus and Acacia). The height of eucalyptus trees is influenced by the consortium with Acacia in the studied CLFI designs, which does not happen with the diameter at breast height. The arrangement of species of eucalyptus and acacia intercropping in the same row planting has productivity equal to the array using only the lines of eucalyptus planting systems . Timber productivity of acacia and eucalyptus in the same row is less than the same species line, however, the sum of the timber produced from the two species is greater than the arrangement of eucalyptus only row in CLFI.

Produtividade de milho adubado com composto de lodo de esgoto e fosfato natural de Gafsa

The aim of this study was to evaluate the yield and concentrations of nutrients in soil and corn plant in response to fertilization with different doses of sewage sludge compost and Gafsa rock phosphate. The work was conducted at experimental area of the ICA/UFMG in a Haplic Cambisol. The treatments, in a factorial 2 x 4, corresponded to two rates of Gafsa rock phosphate (0 and 90 kg P2O5 ha-1) and four rates of sewage sludge compost (0, 25, 50 and 75 t ha-1, on dry basis). The experimental design was randomized blocks, with three replications. In general, the corn yield and the concentrations of macronutrients in soil and plant were not influenced by fertilization with Gafsa rock phosphate. However, corn yield and nitrogen, phosphorus, potassium, calcium and sulfur concentration in the soil and nitrogen, phosphorus and potassium concentration in leaf increased with the addition of sewage sludge compost to soil, being the optimal recommended rate of 75 t ha-1.

Produção de milho adubado residualmente com composto de lodo de esgoto e fosfato de Gafsa

The aim of this study was to evaluate the residual effect of fertilization with sewage sludge compost and rock phosphate on the chemical properties of the soil, nutrient content in plant and corn yield. The study was conducted on Haplic Cambisol. The treatments, in a factorial 2 x 4, corresponded to two doses of Gafsa phosphate (0 and 90 kg P2O5 ha-1) and four doses of sewage sludge compost (0, 25, 50 and 75 Mg ha-1 dry weight basis). The experimental design was in randomized blocks with three replications. In general, the corn yield and content of macronutrients in soil and plant on the second crop of corn were not influenced by the residual effects of fertilization with phosphate rock. However, corn yield and nutrient content in soil and leaves increased with the dose of sewage sludge compost applied to the soil, and the dose of 75 Mg ha-1 was the one with the highest residual effect. The yield of corn was lower in the second successive cultivation, due to the impoverishment of the soil phosphorus and potassium, recommending new fertilization with sewage sludge in every cultivation.

Cobertura morta e adubação orgânica na produção de alface e supressão de plantas daninhas

Objetivou-se, neste trabalho, avaliar os efeitos da cobertura do solo e da adubacao orgânica sobre a temperatura e a umidade do solo, a incidencia de plantas daninhas e a produtividade da alface. O delineamento experimental utilizado foi de blocos casualizados, em esquema fatorial (3 x 3), em que o primeiro fator corresponde aos tipos de cobertura morta (capim tifton, capim napier e ausencia de cobertura) e, o segundo, aos adubos (esterco bovino, esterco de galinhas e ausencia de adubacao). Analisaram-se as variaveis temperatura e umidade do solo, o numero de folhas produzidas pela alface, as massas de materia fresca e seca da parte aerea, das plantas de alface e daninhas, e o levantamento fitossociologico das plantas infestantes. As plantas adubadas com esterco de galinhas apresentaram massas de materia fresca e seca superiores as das plantas nao adubadas. A cobertura morta com capim tifton proporcionou aumento da massa de materia seca das plantas de alface, o que pode estar relacionado com a menor temperatura dos canteiros que receberam esse material como cobertura. Commelina benghalensis foi a planta infestante mais importante no cultivo orgânico de alface. A aplicacao de adubos orgânicos e a cobertura morta com capins nao foram capazes de suprimir plantas daninhas e manter a umidade do solo, em areas de cultivo de alface.

Levantamento fitossociológico e produção de forragem em pasto de capim-gordura

Este estudo foi realizado com o objetivo de efetuar o levantamento fitossociologico em um pasto de capimgordura (Melinis minutiflora P. Beauv.), que vinha sendo pastejado por bovinos de corte, ha mais de dez anos, sem estrategia de manejo definida. A pesquisa foi desenvolvida no campus da Universidade Federal de Vicosa, em Vicosa, MG. Para avaliacao das caracteristicas fitossociologicas e da massa seca das plantas daninhas e da forrageira, utilizou-se o metodo do quadrado inventario, aplicando-se um quadrado de 0,25 m 2 , lancado, ao acaso, 40 vezes, na pastagem, perfazendo uma area amostral de 10 m 2 . Em toda a area experimental, foram identificadas 31 especies e 12 familias botânicas, tendo como destaque as familias Poaceae, com oito especies, e Asteraceae, com sete especies. A forrageira cultivada M. minutiflora P.Beauv., corresponde a 24,26% da producao total de massa seca, entre especies levantadas na area. Estes resultados indicam estadio avancado de degradacao do pasto de capim-gordura, com elevada infestacao por plantas daninhas, inclusive especies consideradas toxicas, epinescentes e de alta competitividade com as forrageiras, o que o caracteriza como pasto de baixa capacidade de suporte. Palavras-chave: diversidade de especies, forrageiras, pastagem degradada, plantas daninhas.