Management Practices for Insect Resistance in Bt Maize

The failure to reduce the population of a phytophagous species recognized as a key pest in a given situation usually occurs by not using the principles of Integrated Pest Management (IPM). The control of insect pests in agriculture has been done mainly through the application of chemical insecticides. However, chemical insecticides has lost effectiveness due to the selection of populations of resistant insects and cause adverse environmental effects. The main resistance management programs (IRM) strategy is the use of ‘high dose/refuge’, which involves the use of high dose of Bt protein in plants, promoting high mortality of heterozygotes associated with the planting of refuge, ie, a proportion of the crop in which it must be planted a non-Bt variety, allowing the survival of susceptible individuals. The emergence of Bt crops is an important step between the tactics available for pest control in various crops such as maize, canola, cotton and, in the near future, soybeans

Co-inoculação e modos de aplicação de Bradyrhizobium japonicum e Azospirillum brasilense e adubação nitrogenada na nodulação das plantas e rendimento da cultura da soja

As new cultivation techniques arise, crops require the development of new technologies and management practices that aim higher yields with lower production cost. Thus, the objective of this study was to evaluate the efficiency of co-inoculation and different ways of application of Bradyrhizobium japonicum and Azospirillum brasilense and nitrogen fertilization on nodulation and yield of soybean. The experiment was established in November 2013 in an area located in the Iguatemi Experimental Farm, of State University of Maringá (UEM). The design was a randomized block with four replications. The treatments consisted of a control, fertilization with nitrogen (200 kg N ha-1), standard inoculation in seeds (liquid and peat inoculant), co-inoculation on seed and co-inoculation at sowing, using different doses of inoculant B. japonicum and A. brasilense. The following determinations were carried out in the field and in the laboratory: number of nodes at flowering, mass of nodules at flowering, the shoot dry mass, nitrogen content in the shoot, grain nitrogen content, number of pods/plant, thousand grain mass and yield. The results showed that inoculation through seed treatment with liquid inoculant presents an adequate option to farmers, in the conditions of this experiment. Nitrogen fertilization did not increase yield and yield components, being unnecessary.À medida que as técnicas de cultivo evoluem, as culturas requerem o desenvolvimento de novas tecnologias e práticas de manejo que almejem maiores rendimentos com menor custo de produção. Desta forma, o objetivo do presente trabalho foi avaliar a eficiência da co-inoculação e de diferentes modos de aplicação de Bradyrhizobium japonicum e Azospirillum brasilense e adubação nitrogenada na nodulação e produtividade da cultura da soja. O experimento foi implantado no mês de novembro de 2013 em área localizada na Fazenda Experimental de Iguatemi, pertencente à Universidade Estadual de Maringá (UEM). O delineamento utilizado foi em blocos casualizados, com quatro repetições. Os tratamentos foram constituídos de uma testemunha, adubação com nitrogênio (200 kg de N ha-1), inoculação padrão nas sementes (inoculante líquido e turfoso), co-inoculação na semente e co-inoculação no sulco de semeadura, utilizando diferentes doses de inoculante a base de Bradyrhizobium japonicum e Azospirillum brasilense. As seguintes determinações foram efetuadas em campo e em laboratório: número de nódulos no início do florescimento, massa de nódulos no início do florescimento, massa seca da parte aérea, teor de nitrogênio na parte aérea, teor de nitrogênio nos grãos, número de vagens/planta, massa de mil grãos e produtividade. Os resultados obtidos permitem concluir que a inoculação via sementes com inoculante líquido apresenta a opção adequada para o produtor rural, nas condições do experimento. A adubação nitrogenada não apresentou incrementos de rendimento e componentes de produtividade, sendo desnecessária

CO-INOCULAÇÃO E MODOS DE APLICAÇÃO DE Bradyrhizobium japonicum e Azospirillum brasilense E ADUBAÇÃO NITROGENADA NA NODULAÇÃO DAS PLANTAS E RENDIMENTO DA CULTURA DA SOJA

As new cultivation techniques arise, crops require the development of new technologies and management practices that aim higher yields with lower production cost. Thus, the objective of this study was to evaluate the efficiency of co-inoculation and different ways of application of Bradyrhizobium japonicum and Azospirillum brasilense and nitrogen fertilization on nodulation and yield of soybean. The experiment was established in November 2013 in an area located in the Iguatemi Experimental Farm, of State University of Maringá (UEM). The design was a randomized block with four replications. The treatments consisted of a control, fertilization with nitrogen (200 kg N ha-1), standard inoculation in seeds (liquid and peat inoculant), co-inoculation on seed and co-inoculation at sowing, using different doses of inoculant B. japonicum and A. brasilense. The following determinations were carried out in the field and in the laboratory: number of nodes at flowering, mass of nodules at flowering, the shoot dry mass, nitrogen content in the shoot, grain nitrogen content, number of pods/plant, thousand grain mass and yield. The results showed that inoculation through seed treatment with liquid inoculant presents an adequate option to farmers, in the conditions of this experiment. Nitrogen fertilization did not increase yield and yield components, being unnecessary

Effect of seed coat on the seed germination and seedling development of Calophyllum brasiliense Cambess. (Clusiaceae)

This work aimed to study the effect of the Calophyllum brasiliense seed coat on the seed germination process. To this end, three experiments were conducted in laboratory, greenhouse and screenhouse. From a total of six treatments, five are related to the seed coat (mechanical scarification; mechanical scarification followed by 2 hours in water, chemical scarification, hot water immersion and complete seed coat removal) and one control. Laboratory and greenhouse experiments were conducted in a completely randomized design (CRD). Screenhouse experiment was conducted in a completely randomized block design (RBD). We evaluated the total percentage, the speed index and the average time of germination or emergence. Data were subjected to analysis of variance and means compared by LSD test, at 5%. Under the conditions of this work, it was possible to infer that, in laboratory, mechanical scarification followed by 2 hours in water increases the proportion and germination speed index (GSI), in the greenhouse, the complete seed coat removal increases the percentage and emergence speed index (ESI), and in the screenhouse, mechanical scarification followed by 2 hours in water and chemical scarification presented the best results. The average germination time was not significantly different in the three experiments evaluated.

Diallel analysis of tropical and temperate sweet and supersweet corn inbred lines

ABSTRACT The number of sweet corn cultivars adapted to the climatic conditions and with agronomic traits recommended to the Brazilian market is still limited. Thus, the aim was to investigate the general and specific combining ability (GCA and SCA, respectively) in relation to the grain yield (GY) and total soluble solid (TSS) contents of seven lines of sweet corn (su1) and eight lines of supersweet corn (sh2) by diallel crosses. For TSS, the inbred lines SC6 and SC7 of sweet corn, and SSC7 and SSC8 of supersweet corn showed higher GCA effect. For GY, the inbred lines SC1 and SC2 of sweet corn and SSC4 and SSC6 of supersweet corn showed higher GCA effect. For TSS in sweet corn, the hybrids '4 × 6' and '1 × 7' showed the superior Ŝij estimates across all evaluated environments. For GY, the hybrid '5 × 7' was the most relevant because it showed higher Ŝij estimates in most of the evaluated environments. Additionally, the hybrids '1 × 4', '3 × 4', and '1 × 7' showed positive Ŝij values across all environments. In supersweet corn, the hybrids '2 × 8', '3 × 6', and '5 × 6' should be selected as the most promising for both traits (TSS and GY), because they presented positive and high Ŝij estimates across the six environments

Popcorn genotypes resistance to fall armyworm

<div><p>ABSTRACT: The aim of this study was to evaluate popcorn genotypes for resistance to the fall armyworm, Spodoptera frugiperda. The experiment used a completely randomized design with 30 replicates. The popcorn genotypes Aelton, Arzm 05 083, Beija-Flor, Colombiana, Composto Chico, Composto Gaúcha, Márcia, Mateus, Ufvm Barão Viçosa, Vanin, and Viviane were evaluated,along with the common maize variety Zapalote Chico. Newly hatched fall armyworm larvae were individually assessed with regard to biological development and consumption of food. The data were subjected to multivariate analyses of variance and genetic divergence among genotypes was evaluated through the clustering methods of Tocher based on generalized Mahalanobis distances and canonical variable analyses. Seven popcorn genotypes, namely, Aelton, Arzm 05 083, Composto Chico, Composto Gaúcha, Márcia, Mateus, and Viviane,were shown to form a cluster (cluster I) that had antibiosis as the mechanism of resistance to the pest. Cluster I genotypes and the Zapalote Chico genotype could be used for stacking genes for antibiosis and non-preference resistance.</p></div

Physiological potential of maize seeds submitted to different treatments and storage periods

Abstract: The aim of the study was to evaluate seed germination and vigor of maize subjected to different products and storage periods. The experimental design was completely randomized in a split plot on time. In the plots were distributed nine treatments: an untreated control, one treatment called “standard treatment”, with addition of fungicide (fludioxonil + metalaxyl-M) and insecticide (thiamethoxam). From the standard treatment, six treatments with combinations of inoculant (Azospirillum brasilense), micronutrients (nitrogen + potassium + zinc + boron + copper + iron + manganese + molibdenium) and bioregulator. Lastly, a treatment called “complete treatment” including all products. In subplots the storage periods of zero, 15, 30, 45, 60 and 90 days were evaluated. Seed vigour of maize was reduced by seed treatments and storage. Micronutrients addition resulted in higher fitotoxicity in comparison to the addition of other products, regardless of storage period. The treatment with the combination of fungicide, insecticide and inoculant proved to be feasible, and was the most promising seed treatments. None of the studied treatments affected the germination in up to 45 days of storage, however the complete treatment with 3200 mL .100 kg-1 reduced seed vigour

Physiological potential of maize seeds submitted to different treatments and storage periods

<div><p>Abstract: The aim of the study was to evaluate seed germination and vigor of maize subjected to different products and storage periods. The experimental design was completely randomized in a split plot on time. In the plots were distributed nine treatments: an untreated control, one treatment called “standard treatment”, with addition of fungicide (fludioxonil + metalaxyl-M) and insecticide (thiamethoxam). From the standard treatment, six treatments with combinations of inoculant (Azospirillum brasilense), micronutrients (nitrogen + potassium + zinc + boron + copper + iron + manganese + molibdenium) and bioregulator. Lastly, a treatment called “complete treatment” including all products. In subplots the storage periods of zero, 15, 30, 45, 60 and 90 days were evaluated. Seed vigour of maize was reduced by seed treatments and storage. Micronutrients addition resulted in higher fitotoxicity in comparison to the addition of other products, regardless of storage period. The treatment with the combination of fungicide, insecticide and inoculant proved to be feasible, and was the most promising seed treatments. None of the studied treatments affected the germination in up to 45 days of storage, however the complete treatment with 3200 mL .100 kg-1 reduced seed vigour.</p></div