Effects of low intensity ultrasound on the germination of corn seeds (Zea mays L.) under different water availabilities

The effects of low intensity ultrasound on the performance of corn seeds (Zea mays L.), were investigated at two intensity levels, 230 and 175 mW/m². This study analysed the ultrasound effects on the germination under different water availabilities. The emergence and development of embryonic structures do react proportionally to the water availability and the treatment with ultrasound has no pronounced influency on the phenomena related to seed germination. However, a tendency of positive interference of this treatment in the seedling development in hidrie deficiency situations is detectable.Foram estudados os efeitos do ultra-som de baixa intensidade (230 e 1750 W/m²) sobre o desempenho de sementes de milho (Zea mays L.) utilizando situações variáveis quanto à disponibilidade hídrica. A emergência e o desenvolvimento de estruturas embrionárias reagem proporcionalmente à disponibilidade de água, não havendo influência marcante do tratamento com ultra-som nos fenômenos envolvidos na germinação das sementes. Contudo, são detectáveis tendências indicadoras de interferência positiva desse tratamento no desenvolvimento das plántulas em situações de deficiência hídrica

Curvas de secagem de sementes de milho utilizando o método intermitente

The objective of this work was the determination of the drying curve of corn seeds for different air temperatures during the intermittent drying process. Three lots of double hybrid AG-162 corn seeds and a D'Andrea dryer, model D-200, were utilized. Air temperatures of 70, 80 and 90°C, were used during the drying process. The following determinations were made: seed moisture content, air temperature at drying, seed temperature in drying roon and drier outled, air relative humidity and environment temperature. Considering the temperature of the drying processes at 70, 80 and 90°C and the reduction of moisture content from 16,5% to 13,0%, the following conclusions were obtained: a) corn seed drying curves in the intermittent drying process can be represented by linear functions; b) the increase of the drying speed and the reduction of total time of seed exposition to hot air can be achieved by temperature elevation of drying air.O presente trabalho teve por objetivo determinar as curvas de secagem de sementes de milho, para diferentes temperaturas do ar, durante a secagem intermitente. Foram utilizados três lotes de sementes de milho do hibrido duplo AG-162 e um secador marca D'Andréa, modelo D-200. As temperaturas do ar de secagem empregadas foram de 70, 80 e 90°C. As seguintes determinações foram realizadas: teor de água das sementes, temperatura do ar de secagem, temperaturas da massa de sementes na câmara de secagem e na saída do secador, umidade relativa do ar e temperatura do ar ambiente. Considerando temperaturas do ar de secagem de 70, 80 e 90°C e reduções do teor de água de 16,5% para 13,0%, os resultados permitem as seguintes conclusões: a) as curvas de secagem de sementes de milho, utilizando o método intermitente, podem ser representadas por funções lineares, b) o aumento da velocidade de secagem e a redução do tempo total de exposição das sementes ao ar aquecido podem ser obtidos pela elevação da temperatura do ar de secagem

Transmissibilidade do virus do mosaico comum da soja (VMCS) por intermédio das sementes de soja(Glycine max (L.) Merrill)

Diante da dispersão do vírus VMCS nas lavouras brasileiras de soja, o presente trabalho foi conduzido procurando verificar a transmissibilidade do patógeno pelas sementes portadoras do sintoma ("mancha café") característico da doença. Para tanto, material proveniente de campos contaminados foi testado quanto às porcentagens de emergência e infecção das plântulas. Os resultados obtidos permitiram concluir que o patógeno é transmitido por sementes, ainda que estas estejam livres de sintomas; contudo, apesar da inexistência de efeitos sobre a emergência, a elevação da freqüência de sementes com "mancha café" tende a ampliar o número de plântulas contaminadas.In view of the long-range dissemination of the virus SMV in Brazilian soybean fields, this research was conserned with the transmission of the pathogen by seeds that show seedcoat mottling. Seeds proceeding from contaminated fields were submitted to emergence tests and examination of infected seedlings. The results indicated that the pathogen is transmited through the seeds even when they do not show seedcoat mottling; although no particular effect was found on emergence percentage, the use of mottled seeds tends to increase the number of infected seelings

Binary Collisions and the Slingshot Effect

We derive the equations for the gravity assist manoeuvre in the general 2D case without the constraints of circular planetary orbits or widely different masses as assumed by Broucke, and obtain the slingshot conditions and maximum energy gain for arbitrary mass ratios of two colliding rigid bodies. Using the geometric view developed in an earlier paper by the authors the possible trajectories are computed for both attractive or repulsive interactions yielding a further insight on the slingshot mechanics and its parametrization. The general slingshot manoeuvre for arbitrary masses is explained as a particular case of the possible outcomes of attractive or repulsive binary collisions, and the correlation between asymptotic information and orbital parameters is obtained in general.Comment: 12 pages, 7 figures, accepted for publication Dec'07, Celestial Mechanics and Dynamical Astronom

Performance evaluation of corn seeds submitted to a partial remotion of the endosperm and the pericarp

Objetivando verificar a interferência da excisão de partes da semente de milho no desempenho biológico, a pesquisa foi conduzida a partir de tratamentos representados por remoções aproximadas de 0, 14, 28 e 37%, em peso, sem que o embrião fosse diretamente afetado. A avaliação, conduzida em laboratório (germinação e vigor) e em campo (emergência e produção), permitiu as seguintes conclusões: - Há a possibilidade biológica de excisar parte (±14% em peso) da semente de milho, em pré-semeadura e com tratamento fungicida, em lotes de alta qualidade fisiológica a serem utilizados em regiões favoráveis ao desenvolvimento da espécie; a retirada de partes da semente de milho contribui para a redução do seu potencial de conservação.In order to verify the interference of the excision of corn seed parts on their biological performance, this research was carried out by removing nearly 0, 14, 28 and 37% in weight from the seed, without influencing the embryo. The evaluation which was carried out in laboratory (germination and vigor) and in the field (outgrowth and yield) allowed the following conclusions: - There is a biological possibility of excising corn seed parts (±14% in weight), in pre-sowing and with fungicidal treatment, in high physiological quality lots to be sowed in suitable areas for the species upgrowth; the remotion of corn seed parts leads to the reduction of its conservation potential

Efeitos do beneficiamento na qualidade de sementes de milho infectadas por Fusarium moniliforme sheld

In order to evaluate processing effects on the quality of corn seeds infected by Fusarium moniliforme Sheld seeds were submitted to screen classification yielding 4 fractions (24/64; 22/64; 20/64; 18/64 of the inch) and the other part was separated by weight in a gravity separator. The separator originated three fractions that in turn were individually submitted to the same equipment generating, each one, three other fractions. All fractions were evaluated for germination, vigor, density, weight of a thousand seeds, and sanity. The width classification is not effective in the selection of infected seeds; however, the increase of seed width is followed by higher germination and vigor values.Com o objetivo de avaliar os efeitos do beneficiamento na qualidade de lotes com sementes de milho infectadas com Fusarium moniliforme Sheld, sementes foram submetidas à classificação por peneiras, originando 4 frações (24/64; 22/64; 20/64; 18/64 de polegada) e à separação por peso através da ação da mesa gravitational, originando três frações que foram individualmente submetidas ao mesmo equipamento gerando, cada uma, mais três frações. Todas as frações foram avaliadas quanto à germinação, ao vigor, à densidade, ao peso de mil sementes e à sanidade. A classificação por largura não é eficaz para separar as sementes infectadas; no entanto, o aumento da largura das sementes é acompanhado pela elevação dos valores da germinação e do vigor

Self-gender schemes: A comparison between individual and collective sport modalities

e aim of this study was to analyze the dierences in gender schemas of self between collective and individual sports. e participants were 140 amateur athletes aged between 13 and 17 years practicing a team sport (indoor soccer) and an individual sport (athletics) in the Chapecó and Florianópolis municipalities of Santa Catarina-SC. e instruments used were the Questionnaire for Socio-Demographic and Training, the Inven- tory Female Gender Schemas of Self-Concept (IFEGA) and the Inventory of Male Gender Schemas of Self-Concept (IMEGA). No dierences in gender schema were found among women athletes who were mostly classi- ed as masculine/ feminine (iso schematic). Among men, the soccer players showed a hetero masculine gender schema, while those in athletics showed an iso schematic scheme. Regarding the variation within the gender schema dimensions, the soccer athletes had higher values in terms of inferiority in relation to those in athletics. Among men, the athletics athletes showed higher values of boldness and lower values of insecurity as compared to soccer athletes. We conclude that gender schemas of self-concept only had variations in the two modalities for male athletes; however, the variations in their constitutive dimensions of schema occurred according to the nature of the sport practiced.

Atlantic frugivory: a plant–frugivore interaction data set for the Atlantic Forest

Non peer reviewe