Detection of genetically modified maize events in Brazilian maize-derived food products

The Brazilian government has approved many transgenic maize lines for commercialization and has established a threshold of 1% for food labeling, which underscores need for monitoring programs. Thirty four samples including flours and different types of nacho chips were analyzed by conventional and real-time PCR in 2011 and 2012. The events MON810, Bt11, and TC1507 were detected in most of the samples, and NK603 was present only in the samples analyzed in 2012. The authorized lines GA21, T25, and the unauthorized Bt176 were not detected. All positive samples in the qualitative tests collected in 2011 showed a transgenic content higher than 1%, and none of them was correctly labeled. Regarding the samples collected in 2012, all positive samples were quantified higher than the threshold, and 47.0% were not correctly labeled. The overall results indicated that the major genetically modified organisms detected were MON810, TC1507, Bt11, and NK603 events. Some industries that had failed to label their products in 2011 started labeling them in 2012, demonstrating compliance with the current legislation observing the consumer rights. Although these results are encouraging, it has been clearly demonstrated the need for continuous monitoring programs to ensure consumers that food products are labeled properly.

Eficiência do modelo Ceres-Maize na simulação do desempenho de híbridos de milho

O modelo Ceres-Maize foi desenvolvido para simulação do desenvolvimento e desempenho da cultura do milho e tem sido utilizado como ferramenta de auxílio no planejamento das safras e tomadas de decisões pelos agricultores de diversos países. Com o objetivo de avaliar a eficiência do modelo Ceres-Maize na simulação do desempenho de híbridos de milho nas condições tropicais, foi conduzido um experimento utilizando cinco híbridos (AG7000, AG8060, DKB199, GNZ2004 e P30F90) avaliados em três épocas de semeadura (24/11/2006, 19/12/2006 e 13/01/2007) na Universidade Federal de Lavras, Lavras, MG. O delineamento foi o DBC com três repetições. Avaliaram-se datas de florescimento e maturidade fisiológica, número de grãos por metro quadrado, massa de grãos e produtividade de grãos, que foram comparados com os dados simulados pelo quadrado médio do erro (RSME), porcentagem de desvio (PD) e índice de concordância (d). Os resultados indicaram que o milho semeado em janeiro apresentou menores valores de número de grãos por metro quadrado, massa de grão e produtividade de grãos do que semeaduras em novembro e dezembro. O Ceres-Maize mostrou-se muito eficiente para simular as datas de florescimento e de maturidade fisiológica em razão dos valores de RSME terem sido inferiores a 10%, os de 'd' superiores a 0,80 e o maior valor de PD -11%. Para o número de grãos por metro quadrado, massa de grãos e produtividade de grãos, a simulação foi considerada boa com valores de RSME inferiores a 20%. Para essas variáveis foram observados maiores valores de PD, principalmente na última época de semeadura, evidenciando que condições ambientais não favoráveis ao bom desempenho da cultura afetam a eficiência da simulação. O modelo Ceres-Maize mostrou ser boa ferramenta de simulação das características agronômicas de híbridos de milho.

Initial growth of maize in response to application of rock phosphate, vermicompost and endophytic bacteria

Due to the high energy requirement and demand for non-renewable resources for the production of chemical fertilizers, added also to the environmental impact caused by the use of such products, it is important to intensify research on bio-based agricultural inputs. The use of nitrogen-fixing endophytic and phosphate solubilizing bacteria can provide these nutrients to the plants from the air and poorly soluble phosphorus sources, such as phosphate rock. The objective of this study was to evaluate the nutrition and initial growth of maize (Zea mays L.) in response to the inoculation of nitrogen-fixing and rock phosphate solubilizing endophytic bacteria, in single or mixed formulation, applied with vermicompost. The treatments containing bacteria, both diazotrophic and phosphate solubilizing, when compared to controls, showed higher levels of leaf nitrogen and phosphorus in maize, as well as higher growth characteristics. The application of vermicompost showed synergistic effect when combined with endophytic bacteria. Thus, the innovation of the combination of the studied factors may contribute to the early development of maize.

Inoculation with Azospirillum, associated with nitrogen fertilization in maize

The biological nitrogen fixation is an alternative to supply the nitrogen needed for maize. The objective of this study was to evaluate the development and yield of maize in response to inoculation with Azospirillum associated with nitrogen fertilization. We conducted two field experiments in the summer harvest, the first in the 2000/2001 crop year in the region of Marechal Cândido Rondon, under conventional tillage, and second in the 2002/2003 agricultural year in the region of Cascavel, under no tillage. The experimental design in both experiments was a randomized complete block, with four replications, 2x2x2 factorial, with two levels of nitrogen at sowing (zero and 20 kg ha-1), two levels of inoculum (zero and 200 g ha-1) and two levels of nitrogen in topdressing (zero and 100 kg ha-1). There was evaluated the height of ear insertion, total plant height, leaf N content, shoot dry biomass and grain yield. The height of ear insertion and total plant height were not influenced by the factors under study. Nitrogen fertilization at sowing increased the leaf N content, causing the opposite effect when combined with inoculation. Inoculation with Azospirillum in the absence of nitrogen, provide productivity increases of 15.4% and 7.4% for 2000/2001 and 2002/2003 crops, respectively. The inoculation provided productivity similar to that obtained with 100 kg ha-1 in topdressing in crop 2000/2001, while in association with the topdressing, reduced productivity and shoot dry biomass in crop 2002/2003.

Initial performance of maize in response to NPK fertilization combined with Herbaspirillum seropedicae

The inoculation with plant growth-promoting bacteria can be a technological approach useful for increasing the production of maize. The objective of this study was to evaluate the initial performance of maize in response to application of doses of NPK combined with the inoculation of the diazotrophic bacteria Herbaspirillum seropedicae in an greenhouse experiment. The experiment consisted of six fertilizer levels: 0, 25, 50, 75, 100 and 200% of the recommended dose of NPK applied to maize inoculated and non-inoculated with H. seropedicae. At 30 days after the treatment application, the growth characteristics and nutritional status of the plants were evaluated. Plant development was influenced by fertilization, but it was enhanced by combination with the bacteria, which resulted in significant increases in the dry mass of shoots (7%) and leaf area (9%) when compared with non-inoculated plants. The results showed increases in the concentration of N (11%), P (30%) and K (17%) of maize plants in response to bacterial inoculation together with NPK compared with plants that were applied fertilize only. The greater consistency and stability response of the host plant to bacterization in the presence of chemical fertilizer indicate a promissory biotechnological approach for improving the initial growth and adaptation of maize to the cultivation environment.

Methods to classify maize cultivars in use efficiency and response to nitrogen

n plant breeding programs that aim to obtain cultivars with nitrogen (N) use efficiency, the focus is on methods of selection and experimental procedures that present low cost, fast response, high repeatability, and can be applied to a large number of cultivars. Thus, the objectives of this study were to classify maize cultivars regarding their use efficiency and response to N in a breeding program, and to validate the methodology with contrasting doses of the nutrient. The experimental design was a randomized block with the treatments arranged in a split-plot scheme with three replicates and five N doses (0, 30, 60, 120 and 200 kg ha-1) in the plots, and six cultivars in subplots. We compared a method examining the efficiency and response (ER) with two contrasting doses of N. After that, the analysis of variance, mean comparison and regression analysis were performed. In conclusion, the method of the use efficiency and response based on two N levels classifies the cultivars in the same way as the regression analysis, and it is appropriate in plant breeding routine. Thus, it is necessary to identify the levels of N required to discriminate maize cultivars in conditions of low and high N availability in plant breeding programs that aim to obtain efficient and responsive cultivars. Moreover, the analysis of the interaction genotype x environment at experiments with contrasting doses is always required, even when the interaction is not significant.

Maize nitrogen fertilization in two crop rotation systems under no-till

The objective of this study was to evaluate split nitrogen (N) fertilization of maize applied in band at sowing and top dressing with and without crop rotation, under no-till. The experiment was conducted with six N rates at sowing (0, 20, 30, 40, 50 and 60 kg ha-1) combined with three rates in top dressing (40, 70, 100 kg ha-1) and two management systems: after five cropping sequences of maize and crop rotation (maize + soybean + oat + soybean + corn) in a randomized block design with four replications. The crop rotation system increased yield in approximately 7% in relation to the area without rotation. The split of nitrogen fertilization, in rates above 39 and 54 kg ha-1 at sowing and 70 and 40 kg ha-1 in top dressing, resulted in yield higher than that obtained with the application of 100 kg ha-1 in top dressing. Grain yield was higher with the rates 50 and 70 kg ha-1 of N compared with that obtained with 20 and 100 kg ha-1 at sowing and top dressing, respectively. The rate 70 kg ha-1 of N resulted in the highest yield at the lowest cost compared with the revenues and costs incurred with the rates 40 and 100 kg ha-1.

Nitrogen and potassium fertilization on the yield and intensity of the maize white spot

A plant's nutritional balance can influence its resistance to diseases. In order to evaluate the effect of increasing doses of N and K on the yield and severity of the mayze white spot, two experiments were installed in the field, one in the city of Ijaci, Minas Gerais, and the other in the city of Sete Lagoas, Minas Gerais. The experimental delimitation was in randomized blocks with 5 x 5 factorial analysis of variance, and four repetitions. The treatments consisted of five doses of N (20; 40; 80; 150; 190 Kg ha-1of N in the experiments 1 and 2) and five doses of K (15; 30; 60; 120; 180 Kg ha-1of K in experiment 1 and 8.75; 17.5; 35; 50; 100 Kg ha-1of K in experiment 2). The susceptible cultivar 30P70 was planted in both experiments. The plot consisted of four rows 5 meters long, with a useful area consisting of two central rows 3 meters each. Evaluations began 43 days after emergence (DAE) in the first experiment and 56 DAE in the second one. There was no significant interaction between doses of N and K and the disease progress P+. The effect was only observed for N. The K did not influence the yield and the severity of the disease in these experiments. Bigger areas below the severity progress curve of the white spot and better yield were observed with increasing doses of N. Thus, with increasing doses of N, the white spot increased and also did the yield.

Diversity and capacity to promote maize growth of bacteria isolated from the Amazon region

ABSTRACT Maize plants can establish beneficial associations with plant growth-promoting bacteria. However, few studies have been conducted on the characterization and inoculation of these bacteria in the Amazon region. This study aimed to characterize endophytic bacteria isolated from maize in the Amazon region and to assess their capacity to promote plant growth. Fifty-five bacterial isolates were obtained from maize grown in two types of ecosystems, i.e., a cerrado (savanna) and a forest area. The isolates were characterized by the presence of the nifH gene, their ability to synthesize indole-3-acetic acid (IAA) and solubilize calcium phosphate (CaHPO4), and 16S rRNA partial gene sequencing. Twenty-four bacteria contained the nifH gene, of which seven were isolated from maize plants cultivated in a cerrado area and seventeen from a forest area. Fourteen samples showed the capacity to synthesize IAA and only four solubilized calcium phosphate. The following genera were found among these isolates: Pseudomonas; Acinetobacter; Enterobacter; Pantoea; Burkholderia and Bacillus. In addition, eight isolates with plant growth-promoting capacity were selected for a glasshouse experiment involving the inoculation of two maize genotypes (a hybrid and a variety) grown in pots containing soil. Inoculation promoted the development of the maize plants but no significant interaction between maize cultivar and bacterial inoculation was found. A high diversity of endophytic bacteria is present in the Amazon region and these bacteria have potential to promote the development of maize plants.

Survey of ear flies (Diptera, Ulidiidae) in maize (Zea mays L.) and a new record of Euxesta mazorca Steyskal in Brazil

Survey of ear flies (Diptera, Ulidiidae) in maize (Zea mays L.) and a new record of Euxesta mazorca Steyskalin Brazil. Species of Euxesta (Diptera, Ulidiidae), known as silk flies or ear flies, are becoming increasingly important as maize insect pests in South America, although very little is known about them in Brazil. The larvae of some species of this genus initially damage female reproductive tissues, and then the developing kernels on the ear. As a result of feeding, fermentation and associated odors cause complete loss of the grain because it is no longer fit for human or livestock consumption. The main objective of this work was to evaluate the incidence of Euxesta spp. in Brazilian maize fields and to determine the most prevalent species using two different hydrolyzed protein foods attractants, BioAnastrepha® (hydrolyzed maize protein) and Torula, placed inside McPhail traps. The two species identified were E. eluta Loew and E. mazorca Steyskal, the latter being a new record from Brazil. Between the two species, E. eluta was the more abundant in maize fields. Both attractants were efficient in capturing the two species. However, BioAnastrepha® captured significantly more insects than Torula.

Larval development of Spodoptera eridania (Cramer) fed on leaves of Bt maize expressing Cry1F and Cry1F + Cry1A.105 + Cry2Ab2 proteins and its non-Bt isoline

This study aimed to evaluate, in controlled laboratory conditions (temperature of 25±2 °C, relative humidity of 60±10%, and 14/10 h L/D photoperiod), the larval development of Spodoptera eridania (Cramer, 1784) (Lepidoptera, Noctuidae) fed with leaves of Bt maize expressing Cry1F and Cry1F + Cry1A.105 + Cry2Ab2 insecticide proteins and its non-Btisoline. Maize leaves triggered 100% of mortality on S. eridania larvae independently of being Bt or non-Bt plants. However, it was observed that in overall Bt maize (expressing a single or pyramided protein) slightly affects the larval development of S. eridania, even under reduced leaf consumption. Therefore, these results showed that Cry1F and Cry1F + Cry1A.105 + Cry2Ab2 can affect the larval development of S. eridania, although it is not a target pest of this plant; however, more research is needed to better understand this evidence. Finally, this study confirms that non-Bt maize leaves are unsuitable food source to S. eridania larvae, suggesting that they are not a potential pest in maize fields.

Does Bt maize cultivation affect the non-target insect community in the agro ecosystem?

ABSTRACT The cultivation of genetically modified crops in Brazil has led to the need to assess the impacts of this technology on non-target species. Under field conditions, the potential effect on insect biodiversity was evaluated by comparing a homogeneous corn field with conventional and transgenic maize, expressing different Bt proteins in seven counties of Minas Gerais, Brazil. The richness pattern of non-target insect species, secondary pests and natural enemies were observed. The results do not support the hypothesis that Bt protein affects insect biodiversity. The richness and diversity data of insects studied were dependent on the location and other factors, such as the use of insecticides, which may be a major factor where they are used.

Growth and metabolic activity of the extramatrical mycelium of endomycorrhizal maize plants

The objective of this experiment was to quantify the extramatrical mycelium of the arbuscular mycorrhizal (AM) fungus Glomus etunicatum (Becker & Gerdemann) grown on maize (Zea mays L. var. Piranão) provided with various levels of phosphate fertilizer and harvested at 30, 60 and 90 days after planting (DAP). Total extramatrical mycelium (TEM) was extracted from soil using a modified membrane filtration method, followed by quantification using a grid intersection technique. Active extramatrical mycelium (AEM) proportion was determined using an enzymatic method which measured dehydrogenase activity by following iodonitrotetrazolium reduction. At low levels of added P, there was relatively less TEM than at high levels of added P, but the AEM proportion at low soil P availability was significantly greater than at high soil P.

Nitrogen application timing and soil inorganic nitrogen dynamics under no-till oat/maize sequential cropping

The timing of N application to maize is a key factor to be considered in no-till oat/maize sequential cropping. This study aimed to evaluate the influence of pre-planting, planting and sidedress N application on oat residue decomposition, on soil N immobilisation and remineralisation and on N uptake by maize plants in no-till oat/maize sequential cropping. Undisturbed soil cores of 10 and 20 cm diameter were collected from the 0-15 cm layer of a no-till Red Latossol, when the oat cover crop was in the milk-grain stage. Two greenhouse experiments were conducted simultaneously. Experiment A, established in the 10 cm diameter cores and without plant cultivation, was used to asses N dynamics in soil and oat residues. Experiment B, established in the 20 cm diameter cores and with maize cultivation, was used to assess plant growth and N uptake. An amount of 6.0 Mg ha-1 dry matter of oat residues was spread on the surface of the cores. A rate of 90 kg N ha-1 applied as ammonium sulphate in both experiments was split in pre-planting, planting and sidedress applications as follows: (a) 00-00-00 (control), (b) 90-00-00 (pre-planting application, 20 days before planting), (c) 00-90-00 (planting application), (d) 00-30-60 (split in a planting and a sidedress application 31 days after emergence), (e) 00-00-00* (control, without oat residue) and (f) 90-00-00* (pre-planting application, without oat residue). The N concentration and N content in oat residues were not affected during decomposition by N fertilisation. Most of the fertiliser NH4+-N was converted into NO3--N within 20 days after application. A significant decrease in NO3--N contents in the 0-4 cm layer was observed in all treatments between 40 and 60 days after the oat residue placement on the soil surface, suggesting the occurrence of N immobilisation in this period. Considering that most of the inorganic N was converted into NO3- and that no immobilisation of the pre planting fertiliser N occurred at the time of its application, it was possible to conclude that pre-planting applied N was prone to losses by leaching. On the other hand, with split N applications, maize plants showed N deficiency symptoms before sidedress application. Two indications for fertiliser-N management in no-till oat/maize sequential cropping could be suggested: (a) in case of split application, the sidedress should be earlier than 30 days after emergence, and (b) if integral application is preferred to save field operations, this should be done at planting.

Maize response to nitrogen fertilization timing in two tillage systems in a soil with high organic matter content

No-tillage systems, associated to black oat as preceding cover crop, have been increasingly adopted. This has motivated anticipated maize nitrogen fertilization, transferring it from the side-dress system at the stage when plants have five to six expanded leaves to when the preceding cover crop is eliminated or to maize sowing. This study was conducted to evaluate the effects of soil tillage system and timing of N fertilization on maize grain yield and agronomic efficiency of N applied to a soil with high organic matter content. A three-year field experiment was conducted in Lages, state of Santa Catarina, from 1999 onwards. Treatments were set up in a split plot arrangement. Two soil tillage systems were tested in the main plots: conventional tillage (CT) and no-tillage (NT). Six N management systems were assessed in the split-plots: S1 - control, without N application; S2 - all N (100 kg ha-1) applied at oat desiccation; S3 - all N applied at maize sowing; S4 - all N side-dressed when maize had five expanded leaves (V5 growth stage); S5 - 1/3 of N rate applied at maize sowing and 2/3 at V5; S6 - 2/3 of nitrogen rate applied at maize sowing and 1/3 at V5. Maize response to the time and form of splitting N was not affected by the soil tillage system. Grain yield ranged from 6.0 to 11.8 t ha-1. The anticipation of N application (S2 and S3) decreased grain yield in two of three years. In the rainiest early spring season (2000/2001) of the experiment, S4 promoted an yield advantage of 2.2 t ha-1 over S2 and S3. Application of total N rate before or at sowing decreased the number of kernels produced per ear in 2000/2001 and 2001/2002 and the number of ears produced per area in 2001/2002, resulting in reduced grain yield. The agronomic efficiency of applied N (kg grain increase/kg of N applied) ranged from 13.9 to 38.8 and was always higher in the S4 than in the S2 and S3 N systems. Short-term N immobilization did not reduce grain yield when no N was applied before or at maize sowing in a soil with high organic matter content, regardless of the soil tillage system.