O trabalho foi realizado com objetivo de avaliar a qualidade das sementes de quatro cultivares de soja (BRS 133, BRS 206, BRS 239 e CD 202), colhidas em quatro épocas (Estádio R7 e 7, 14 e 21 dias após a primeira época) e produzidas em dois locais do Estado do Mato Grosso do Sul (Sidrolândia e Dourados), nos anos agrícolas de 2004/05 e 2005/06. O delineamento experimental utilizado foi em blocos casualizados com três repetições e tratamentos arranjados no esquema de parcelas subdivididas. As parcelas foram constituídas pelas cultivares de soja e as subparcelas pelas épocas de colheita. A germinação foi avaliada pelo teste de germinação; teste de envelhecimento acelerado e o vigor pelo teste de frio sem solo, teste de emergência das plântulas em substrato de areia e teste de sanidade. Os dados coletados nos diferentes locais foram submetidos à análise de variância conjunta de parcelas subdivididas e, na presença de interação significativa, foram realizados os desdobramentos necessários para os dois anos agrícolas, separadamente. No ano agrícola 2004/05, as cultivares BRS 239 e CD 202 apresentaram-se com elevada porcentagem de germinação para a produção de sementes na região de Dourados. No ano agrícola 2005/06, a cultivar BRS 239 foi a que apresentou melhor germinação e vigor. A cultivar BRS 239 apresenta menor índice de infecção de microrganismos em relação a cultivar BRS 206. Melhor qualidade de sementes é obtida das sementes colhidas aos sete dias após o estádio R7. Em relação à qualidade sanitária das sementes, à medida que se retarda a época de colheita, a porcentagem total de microrganismos aumenta linearmente para todas as cultivares.

Background In the last two decades, herbicide-resistant biotypes of Conyza bonariensis, Conyza canadensis, and Conyza sumatrensis were identified. Objective: To evaluate herbicide alternatives for the control of C. sumatrensis to replace simplified management at soybean pre-sowing in the no-till system and assess the potential herbicide injury to soybeans. Methods Four experiments were conducted in Palotina, PR, to evaluate alternative managements to the herbicides commonly used in C. sumatrensis , such as synthetic auxins, pre-emergent, and burndown herbicides. All consisted [...] Abstract Background In the last two decades, herbicide-resistant biotypes of Conyza bonariensis, Conyza canadensis, and Conyza sumatrensis were identified. Objective: To evaluate herbicide alternatives for the control of C. sumatrensis to replace simplified management at soybean pre-sowing in the no-till system and assess the potential herbicide injury to soybeans. Methods Four experiments were conducted in Palotina, PR, to evaluate alternative managements to the herbicides commonly used in C. sumatrensis , such as synthetic auxins, pre-emergent, and burndown herbicides. All consisted

The application of vegetal bioregulators has shown promising results, mainly in cultures that have already reached a high level of technology. Based on this context an experiment was carried out with the objective of evaluating agronomic traits of plants, such as yield and quality of seeds, produced by applying bioregulators to a soybean crop. For this purpose, the following treatments were carried out: before sowing - seed treatment (25, 50 and 75 mL for 100 kg-1 seeds); during sowing time - spraying on the sowing lines (pulverization onto the sowing lines) (50, 100 and 150 mL ha-1); between stages V5 and V6 (25, 50 and 75 mL ha-1); and the control - no treatment. Emergence speed, final seedling emergence, number of pods and seeds per plant, average height of plants, first pod insertion height, duration of the cycle, final stand, degree of plant layering, and the yield and weight of one thousand seeds were evaluated. The quality of seeds was evaluated based on germination, classification of seedling vigor, tetrazolium, health test and the quantity of oil and protein tests. The highest yield of grains, an increase of 92% as compared to the control, was obtained when using the product at a dose of 75 mL ha-1. The best quality seeds and the highest oil and protein content were obtained from seeds produced by plants whose seeds were treated before sowing time using the bioregulator (75 mL for 100 kg-1 seeds).

Fleabane (Conyza spp.) is an important weed in grain production systems and is currently one of the most problematic weeds in Brazil. An important factor related to weeds such as fleabane is the characteristic of herbicide-resistant biotypes developed under selection pressure, with multiple resistance previously detected for Conyza spp. Thus, the aim of this study was to demonstrate the multiple resistance of Conyza sumatrensis to the herbicides paraquat, glyphosate, and chlorimuron. From the F2 seeds of biotypes with suspected resistance to paraquat, glyphosate, and chlorimuron, dose-response greenhouse experiments were conducted for the three herbicides. Herbicides were applied when the plants had 6-8 leaves that were at a height of 8 cm. At the end of the evaluations, 28 days after application, multiple resistance to paraquat, glyphosate, and chlorimuron was observed, with resistance factors (RF₅₀) for the control of 7.43, 3.58, and 14.35 and for the reduction of dry mass of 2.65, 2.79, and 11.31, respectively. All the established criteria for demonstrating new cases of weed resistance were met; thus, the first case worldwide of a Conyza species with resistance to herbicides with three different mechanisms of action was confirmed.