Efeito alelopático do extrato aquoso de folhas de girassol sobre a germinação de soja e picão-preto

The aim of this work was to evaluate the allelopathic effect of water extract from sunflower fresh leaves on the germination and initial development of conventional and transgenic soybean cultivars, and of the invasive hairy beggartick (Bidens pilosa L.). Experiments were carried out at Laboratory of Plant Physiology, Universidade Estadual do Oeste do Parana, in 2007. Fresh leaves from sunflower were ground in a blender at the proportion 200g/1L distilled water, resulting in crude extract (100%), in which pH was measured. Dilutions of 80%, 60%, 40% and 20% were done from the crude extract, and only distilled water was used as control. Statistical analysis (Tukey 5% probability) indicated that only the highest extract concentrations (60%, 80% and 100%) influenced the analyzed parameters for conventional and transgenic soybean. Beggartick seeds, however, had germination percentage completely inhibited when 40% water extract was applied, which indicates that sunflower straw could be used as a natural herbicide. Nevertheless, field studies must be carried out to prove such effect.

Comportamento de cultivares de soja quanto a qualidade fisiológica de sementes

This work was carried out in order to evaluate if there was a relationship between genotypes and the physiological soybean (Glycine max L.) seed quality. It was conducted during three years using seven cultivars each year. The seeds were harvested at: 1) yellow radicle or expanded pod stage, 2) yellow pod or physiological maturity (R7), 3) harvest maturity (R8), and 4) R8 + 21 days delay. Seed moisture content, standard germination, and vigor tests were performed. The germination and vigor evaluated by accelerated aging and electrical conductivity did not show physiological seed quality differences among genotypes as harvested at physiological maturity. Then, the evaluation of seed germination and vigor, when the environment is not a considered factor, is not an efficient method to show differences among soybean genotypes in terms of seed quality.

Eficiência de absorção e utilização de potãssio por plantas de soja em solução nutritiva

A greenhouse experiment was conducted in a factorial design of randomized complete blocks, with three replications, to study plantage response of soybean cultivars on efficiency: update (EAB); conversion (EC) and utilization, as well as utilization index (IU) by soybean cultivars. Four soybean cultivars (IAC 17, IAC 18, IAC 11 e FT 2) were grown in nutrient solutions with either adequate or deficient K levels (0.5 and 1.82 mmol. L-1) and harvested 20, 40 and 60 days after plant emergence (DAPE). The plants were separated in top, median and lower leaves, stems and roots, dried, ground and analyzed for K contents. Regardless of cultivar, in deficient plants K was translocated from the other organs to median leaves, in order to maintain its K contents. This behavior was particularly evident in 'IAC 11' and 'IAC 18'. Well nourished plants showed higher EAB than deficient plants. 'IAC 17' and 'IAC 18' showed higher EAB at either adequate or deficient K. levels. 'FT 2' showed highest EUK in deficient solutions at 40 DAPE (immediately before flowering), and the lowest EUK at 60 DAPE. The utilization index was helpful in determining cultivar plasticity to adapt to K deficiency. The highest plasticity was observed for 'FT 2' at 40 DAPE and for 'IAC 18' at 60 DAPE. K-deficient plants were more efficient in EC, yielding more dry matter for K uptake unit.

Biologia comparada de Trialeurodes vaporariorum (West.) (Hemiptera - Homoptera: Aleyrodidae) em soja e cinco cultivares de feijão

With the development of greenhouse grown crops, the whitefly Trialeurodes vaporariorum (West.) has become an important pest. Aiming at verifying the effect of host on the development of this species, the biology of the whitefly was studied on bean (Phaseolus vulgaris L.) cultivars IAC-Carioca Pyatã, IAPAR-57, Jalo Precoce, IAC-Bico de Ouro, IAC-Maravilha and on soybean (Glycine max L.) cultivar Cristalina. The study was conducted at the Laboratório de Entomologia Agrícola - FCA-UNESP, at 25 ± 3°C temperature, 80 ± 10% RH and 14h photophase. The biological parameters assessed were duration, viability and number of nymphal instars; male and female longevity, oviposition period, number of eggs per female and sex ratio; egg viability and incubation period and the life cycle duration. Based on data obtained, fertility life tables were constructed to allow a comparative analysis of the effect of cultivars on the biological development and consequent population growth of this species. The bean cultivars IAC-Maravilha and Jalo Precoce negatively influenced T. vaporariorum development, whereas, the other bean cultivars studied, as well as the soybean cultivar Cristalina, provided good conditions for development of this pest.

Influência da cobertura de aveia-preta e milheto sobre comunidade de plantas daninhas e produção de soja

The success in weed control by using straw depends on the management time, straw quality and quantity. The objective of this research was to evaluate the suppressor effect of black-oats and millet straw cover on the incidence of weeds and on the productivity of the soybean crop. The experiment was carried out during the years 2006 and 2007, in an area from the Farm of Education, Research and Production of FCAV-UNESP, Jaboticabal Campus, in a completely randomized block design, with four replications. Treatments consisted of different types of black oats and pearl millet straw management before soybean seeding (without management, obtained by machine cut, desiccated using glyphosate desiccation and with paraquat) and different periods of straw deposition (0, 15, 30 e 60 days before soybean seeding). The weed population and the characteristics of soybean growth and production were evaluated. The deposition of black oats and pearl millet straw provided reductions in weed density and dry mass, and this effect was more effective when the deposition occurred until 15 days prior to soybean seeding. The suppressor effect of black oats straw was more pronounced than that of pearl millet straw, regardless of the drying method, although the millet had a greater dry matter production. No significant differences were found between the drying methods and the straw effectiveness.

Dissimilaridade genética e análise de trilha de cultivares de soja avaliada por meio de descritores quantitativos

In addition to the evaluations among genotypes, the use of multivariate techniques enables to restrict errors, mainly concerning genetic diversity, and therefore to predict combinations with greater heterotic effect, and the greater possibility of recovery of superior genotypes. The objective of this study was to evaluate the genetic divergence between 18 soybean cultivars based on six morphological characteristics. Path analysis was performed to verify the contribution of direct and indirect characters on grain yield. The Mahalanobis distance has founded techniques of both Tocher Method and dendrogram by Single Linkage. Five different groups were formed: with nine genotypes considered similar among them; while the cultivars CEP 59, Netuno and Urano formed groups isolated by the two grouping methods. The path analysis showed that the indirect characters had little influence on grain yield, with significant direct relationship with mass of 100 grain, and cultivars Tertulha and CEP 53 standing out with grain yields above 3.7 t.ha-1.

Perdas qualitativas na colheita mecanizada de sementes de soja

The study aimed to assess the physical and physiological characteristics of soybean seeds collected in grain tank and the outlet of the discharge tube of the harvester, depending on the year and the forward speed of the harvester. The experimental design was completely randomized in a factorial 2 x 2 x 2 tested two harvesters of different years, two displacement's speeds and two locations of sample collection, totaling eight treatments with four replications. The harvest of soybean cv. COODETEC 217, was performed with two tangential harvesters, aged three and four years, with 900 rpm rotation of the cylinder, operating at forward speeds of 4 ± 0.5 km h-1 and 7 ± 0.5 km h-1. Seed samples (approximately 3 kg) were withdrawn at the grain tank and the outlet of the discharge tube of the harvester and subjected to determinations of water content in field and laboratory. Subsequently, we evaluated purity, mechanical damage, germination and seed vigor. The younger harvester had a higher percentage of pure seed and lowest percentage of inert material. The increase in forward speed provides the higher the bands percentage and reduction of percentages of pure seed and inert material. The percentage of inert material was higher for seeds collected in the discharge pipe. The speed increase has positively influenced the emergence in sand for the harvester oldest (4 years) and negatively to the harvester youngest (3 years). At lower speeds the youngest harvester higher percentage of germination in sand.

Structural changes in soybean seed coat due to harvest time and storage

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Evaluation of late vegetative and reproductive stage soybeans for resistance to soybean aphid (hemiptera: Aphididae)

The soybean aphid, Aphis glycines Matsmura, has become the most significant soybean [Glycine max (L.) Merrill] insect pest in the north central soybean production region of North America. The objectives of this research were to measure selected genotypes for resistance to the soybean aphid in the later vegetative and reproductive stages under field conditions, and confirm the presence of tolerance in KS4202. The results from 2007 to 2011 indicate that KS4202 can support aphid populations with minimal yield loss at levels where significant yield loss would be expected in most other genotypes. The common Nebraska cultivar, 'Asgrow 2703′, appears to show signs of tolerance as well. None of the yield parameters were significantly different between the aphid infested and noninfested treatments. Based on our results, genotypes may compensate for aphid feeding in different ways. Asgrow 2703 appears to produce a similar number of seeds as its noninfested counterpart, although the seeds produced are slightly smaller. Field evaluation of tolerance in KS4202 indicated a yield loss of only 13% at 34,585-53,508 cumulative aphid-days, when 24-36% yield loss would have been expected. © 2013 Entomological Society of America.

Effect of reduced fungicide doses on control of soybean Asian rust and bean yield

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Aspectos fisiológicos e bioquímicos de cultivares de soja submetidos a déficit hídrico induzido por peg 6000

In soybean culture water deficit is one of the most limiting factors to the maximum yield obtained. Genotypes identification with drought tolerance capacity is fundamental to solve this problem. The objective in this paper was analyze the physiological quality and physiological and biochemical responses of soybeans cultivars (MG/BR 46 Conquista, UFUS Carajás, UFUS Impacta, UFUS Riqueza and UFUS Xavante) submitted to water stress with PEG 6000 solutions in different levels of osmotic potentials (0; -0,1; -0,2; -0,3 and -0,4 MPa). Physiological quality of cultivars were evaluated by seedling length test and fresh and dry biomass. The biochemical responses were evaluated by detection of indol-acetic acid (IAA), by saccharose content and seedling water transportation. UFUS Riqueza presented the best performance in physiological quality tests, saccharose content, absorption and water absorption velocity in seedling. UFUS Xavante showed the highest IAA's concentration and the greater weight of seedling in water transportation test.

Desempenho de cultivares transgênicas de soja em sucessão a culturas de inverno em semeadura direta

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Avaliação do sistema radicular da soja sob sistemas de manejo do solo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Absorção e acúmulo de manganês em soja RR sob efeito do glyphosate

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Disponibilidade de fósforo para a soja cultivada sobre braquiária

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)