Renato Mendes Guimarães

Compactação do solo e manejo da água. I: efeitos sobre a absorção de N, P, K, massa seca de raízes e parte aérea de plantas de arroz

Com o presente trabalho objetivou-se avaliar os efeitos de seis niveis de compactacao, associados a diferentes manejos de agua, sobre a absorcao de nitrogenio (N), fosforo (P) e potassio (K), o desenvolvimento do sistema radicular e parte aerea de plantas de arroz. O experimento foi conduzido no periodo de setembro de 2002 a janeiro de 2003 em casa- de-vegetacao da UFLA, em Lavras-MG. Testou-se seis niveis de compactacao do solo: 0%, 16%, 32%, 48%, 64% e 80% da amplitude de variacao da densidade do solo (0,25 kg dm-3), combinado com tres teores de agua no solo: solo saturado, irrigado quando eram consumidos de 25% a 30% e de 50% a 60% da agua disponivel, respectivamente. O manejo com maior disponibilidade de agua no solo favoreceu as medias dos teores de P e de K na parte aerea das plantas, a producao de massa seca da raiz, o numero de perfilhos por vaso e a massa seca da parte aerea das plantas de arroz, independentemente dos niveis de compactacao do solo. Por outro lado, a compactacao do solo diminuiu as medias de todas caracteristicas avaliadas, independentemente do manejo de agua. Entretanto, o manejo de agua teve efeito mais limitante sobre a absorcao dos nutrientes e a producao de massa seca da parte aerea das plantas do que a compactacao do solo.

Inoculação de sementes de milho utilizando o Trichoderma harzianum como promotor de crescimento

Conduziu-se este trabalho com o objetivo de estudar o efeito do fungo Trichoderma harzianum como promotor de crescimento de sementes de milho tratadas com diferentes fungicidas. O experimento foi realizado em vasos em casa-de-vegetacao, adotando o delineamento experimental inteiramente casualizado em esquema fatorial (3x2), utilizando os tratamentos com fungicidas: Captan®, Maxim® e testemunha e inoculacao (com e sem inoculo) em quatro repeticoes. As caracteristicas agronomicas avaliadas foram: altura de planta, peso da materia seca da parte aerea e de raizes e tambem a tecnica de isolamento do fungo nas raizes aos 45 dias apos semeadura. Observou-se diferenca significativa somente para o fator inoculo na caracteristica peso de materia seca de raizes. Pelos resultados obtidos, verificou-se que o fungo Trichoderma harzianum estimulou maior acumulo de materia seca nas raizes das plantas de milho e tambem estava presente nas raizes das plantas oriundas de sementes inoculadas, independentemente do tratamento fungicida das sementes.

Morfologia de frutos, sementes e de plântulas de janaguba (Himatanthus drasticus (Mart.) Plumel. - Apocynaceae)

The objectives of this study were to describe and illustrate the morphological aspects of janaguba (Himatanthus drasticus (Mart.) Plumel.) fruit, seed and seedlings. All the experiments were conducted at the Laboratory of Seed Analysis of the Federal University of Ceara. The following characteristics were studied in janaguba fruits: type, dehiscence, dimension, consistency and coloration of the epicarp, mesocarp, endocarp and placenta. In janaguba seeds the characteristics studied were dimension, colour, texture, consistency of the tegument, shape, edges, hilum, micropyle and rafe positions, embryo, cotyledons, hypocotyl-radicle axes, and plumule. The janaguba seedling root system, hypocotyls, epicotyls, and first leaves were evaluated. Ruler and pachimeter were used to take the measurements, as well as optical microscope and magnifying glass. The janaguba fruit is full of seeds (42 seeds in average), winged; seeds are the albumin type and present epigeous germination.

Avaliação da qualidade de sementes de Tabebuia serratifolia Vahl Nich. e T. impetiginosa(Martius ex A. P. de Candolle) Standley - (Bignoniaceae) pelo teste de raios X

4RESUMO - Para estudar a eficiencia do teste de raios X na avaliacao de defeitos internos em sementes de ipe-amarelo (Tabebuia serratifolia) e ipe-roxo (T. impetiginosa), bem como verificar a consequencia destes defeitos na germinacao, as sementes foram submetidas a diferentes intensidades e tempos de exposicao a radiacao. Definida a intensidade de 55 kV por 25 segundos como sendo a que permitiu melhor visualizacao das estruturas internas, as sementes das duas especies foram divididas em tres categorias de acordo com a sua analise radiografica em: Sem Defeitos, Com Defeitos e Vazias. As Sementes Com Defeitos foram divididas em tres subcategorias: Com Pequenos Danos (menos de 50% do embriao danificado), Com Danos Severos (mais de 50% do embriao danificado) e Deformadas. As sementes foram, entao, submetidas ao teste de germinacao em substrato sobre areia, a 30 o C, sob luz constante. O teste de raios X e eficiente na avaliacao de defeitos em sementes de ipe-amarelo e ipe-roxo. Defeitos internos detectados nas radiografias afetam a germinacao dessas sementes, reduzindo a qualidade do lote.

Physiological and biochemical alterations during germination of sucupira-preta (Bowdichia virgilioides Kunth.) seeds

This research aimed to evaluate the alterations in black sucupira seeds during imbebetion and the modifications in some enzymes and proteins during this process. The seeds were imbibed in wet paper roll at 30°C and weighted for 6 hours until the root protrusion of 50% of the seeds, then the seeds were submitted to the protein analysis by electrophoresis technique. The imbebition curve of the black sucupira has a triphasic model. The evaluation of enzymatic systems shoed the same pattern for the enzymes superoxide dismutase and malate dehidrogenase. For the enzymes alcohol dehidrogenase, catalase and α-amylase, the band intensity varied according to the seed lot used. For the protein resistant to heat, the presence of bands was observed throughout the germination, with alterations in intensity during the process.

Desempenho de sementes de pimentão revestidas com diferentes materiais

The technique of covering seeds has been used mainly for the species which have small seeds, such as vegetables, forage, forest and ornamental species, because besides increasing the size of the seeds for direct sowing, it is possible to add other elements which are necessary for the good development of the plant in its early stages. In this context the objective of the present study was to covered green-pepper seeds in different types of materials and to evaluate their behavior during storage. Seeds treated and not treated with Rovrin at the dosage of 200g/100kg were submitted to pre-conditioning for the imbibing of seeds in KNO3 in -1,1Mpa solution, in an aired system for 5 days. After drying the seeds were covered in a mixture of sand + microcellulose and another of limestone + microcellulose. The covered seeds and those not covered were dried and packed in paper envelopes (permeable pack) and in aluminum envelopes (impermeable pack) and stored at room temperature in the Seeds Analysis Laboratory at UFLA. The seed quality was evaluated once every four months, for a period of 20 months, using the following parameters: water content, germination test, accelerated aging, controlled deterioration and emergency in soil + sand. From the results, it was possible to conclude that the covering of seeds slows but does not affect the germination rate of the green pepper seeds before storage, but the covered seeds deteriorate faster than the seeds not covered, when stored in permeable packs. The nature of the materials used did not affect the quality of the green pepper seeds stored in impermeable packs.

Métodos para a superação da dormência em sementes de sucupira-preta (Bowdichia virgilioides Kunth.)

Neste estudo foram avaliados diferentes metodos para a superacao da dormencia em sementes de sucupira-preta. O experimento foi realizado inteiramente ao acaso em esquema fatorial 3 x 7, correspondendo a tres lotes de sementes e sete tratamentos, com 4 repeticoes de 25 sementes. Foram utilizados acido sulfurico por 4, 8 e 12 minutos, agua a 80°C por 5 e 10 minutos, escarificacao mecânica, mantendo-se uma testemunha. Foi observado que a especie possui dormencia tegumentar e que todos os tratamentos utilizados permitiram a entrada de agua nas sementes. Contudo, alguns metodos estudados, como a agua a 80°C por 10 minutos, resultou em um elevado numero de sementes mortas. O metodo mais eficiente para a superacao da dormencia de sementes de sucupira-preta e a imersao em acido sulfurico, por 4, 8 ou 12 minutos, beneficiando a porcentagem e a velocidade de germinacao.

Efeito da secagem, do armazenamento e da germinação sobre a micromorfologia de sementes de Eugenia pyriformis Camb

Eugenia pyriformis Camb. is a tree species of medium height that produces savory fruits with large thin-coated seeds. These seeds quickly lose viability when submitted to desiccation. Our aim was to investigate embryo structure in E. pyriformis seeds and the ultra-structural changes that result from drying, germination and storage. The axis was less than 1.0 mm long, while the fleshy cotyledons varied from 1.0 to 2.0 cm. The apical and radicular meristem lie in opposing positions. There is a procambium and a medulla of parenchymatous nature, rich in starch grains. Leafy primordia were identified around the stem meristem and there were unicellular trichomes and stomata on the adaxial epidermis of the cotyledons. The gradual desiccation of the seeds provoked cellular structure disarrangement, which also occurred as the seeds aged. Apical meristem form changed from concave to conical during germination and the radicular hypocotyl axis became elongated, with root protrusion. In this phase, the cells have structured content and hydrolysis of reserves. Seed water content variation was evaluated and the physiological consequences of this change are discussed.

Tratamento fungicida e peliculização de sementes de soja submetidas ao armazenamento

O tratamento de sementes de soja com fungicidas vem sendo utilizado como importante ferramenta no controle de patogenos. Nesse trabalho, objetivou-se estudar o desempenho de sementes de soja tratadas com fungicidas e peliculizadas, antes e apos o armazenamento. Foram utilizados cinco lotes de sementes, cultivar Monsoy 6101, submetidos aos tratamentos: thiabendazole+thiram sem polimero, carbendazin+thiram sem polimero, sem fungicida (testemunha) sem polimero, alem desses tratamentos realizados via peliculizacao (com polimero). A qualidade fisiologica e sanitaria das sementes foi avaliada inicialmente e apos seis meses de armazenamento em condicoes ambientais, pelas seguintes determinacoes: teor de agua, teste de germinacao, emergencia em bandeja, teste de frio e de sanidade. Conclui-se que a peliculizacao, em associacao com fungicidas, nao afeta a qualidade fisiologica das sementes de soja e o tratamento de lotes de sementes de soja com os fungicidas thiabendazole+thiram e carbendazin+thiram melhora seu desempenho e qualidade sanitaria.The treatment of soybean seeds by fungicides has been used as an important tool in pathogen control. The objective of this work was to verify the performance of soybean seeds treated with fungicide and film coating, prior and after storage. Five seed lots, cultivar Monsoy 6101, were treated with thiabendazole+thiram without polymer, carbendazin+thiram without polymer, without fungicide (control), without polymer, and treatments by film coating (with polymer). The physiological and sanitary quality of the seeds was evaluated initially and after six months storage, under environmental conditions, according to the following characteristics: water content, test of germination and emergence on tray, blotter test and cold test. The film coating associated with fungicides does not affect the physiological quality of soybean seeds and the soybean seed treatment with the fungicides thiabendazole+thiram and carbendazin+thiram improves performance and sanitary quality.

Efeito de diferentes materiais de peletização na deterioração de sementes de tomate durante o armazenamento

The pelleting of vegetable seeds is a very common technique, mainly for the species which have small seeds. One of its functions is to increase the seed size for direct sowing. The present study verified the pelleting of tomato seeds with different types of materials and to evaluated the performance during seed storage. The materials used as pelleting coats were sand + microcellulose and limestone + microcellulose, with and without Rovrin fungicide (200g/100kg of seeds). Raw seeds were covered, and treated with or without fungicides. Then, seeds were dried and put in paper envelopes (permeable) and in aluminum foil (impermeable) and stored at room temperature at the Universidade Federal de Lavras Seed Lab. The evaluation of seed quality was done once every four months, for 24 months, using the following determinations: germination test, accelerated aging and emergence on soil + sand. Covered seeds presented slower germinatnion than the raw seeds. Seeds covered with limestone + microcellulose deteriorated faster than the ones with sand + microcellulose and seeds treated with fungicides in association with the pelletting