Características morfoagronômicas do milho submetido a diferentes níveis de desfolha manual

The present study was conducted to evaluate the damage caused by defoliation in maize. The experiment was carried out in 2005/2006 at Roma Farm, Ituverava-SP, using the triple hybrid CODETEC 304®. The experiment consisted of split plots (split-plot), which were distributed at random in three blocks, with the main treatment manual defoliation (30%, 40%, 60% and 80% defoliation) in the plots and as the secondary treatment the phenological phases (D1, D2 and D3) with three replicates for each treatment and a control plot (0% defoliation) for each block. It was evaluated the production of plots (g/m2), the average size of the spikes (cm) and the average weight of thousand grains (g). According to the results, it was concluded that the source-sink relations were negatively affected, and the treatment with 80% defoliation was the one that most affected all variables, thus, it is a level of defoliation that is responsible for the largest losses, with no means of compensation for the maize crop.

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.

Degradabilidade ruminal da matéria seca de grãos de milho e de sorgo com alto ou baixo conteúdo de tanino processados

This work evaluated the effects of high moisture silage, extrusion and corn and sorghum drying with and without tannin, on the chemical composition and ruminal digestion of dry matter. The experimental design was completely randomized in 3x3 factorial scheme (kinds of grains: processing), for the chemical composition and degradability and three blocks (animals) through in situ method. It was verified significant difference between kinds of grains and processing in relation to the chemical composition, except for crude protein and mineral matter. The contents of etherextract in the three types of grains, were reduced significantly with the high moisture silage, extrusion and drying in relation to the humid material. For the contents of phenols, total and condensed tannin there was effect of hybrid, processing and interaction, and the most elevated contents were found in sorghum with tannin. Although grain composition has been similar, the interaction in ruminal ambient associated to the tannin, promoted differences in the dry matter degradability. It was concluded that sorghum without tannin may be ensiled or extruded, while the sorghum with tannin, must be extruded to improve the degradability and availability of nutrients.

Desempenho de fungicidas no controle da mancha-de-macrospora na cultura do milho

Fungicide application is one of the control strategies of fungal diseases in corn leaves. In Brazil, there are no fungicides recorded for the control of corn macrospora leaf spot (MLS). The aim of this study was to assess the efficacy of 16 fungicides on MLS control in a protective, curative and eradicant form. Fungicides of the chemical groups of benzimidazoles, strobilurins and triazoles were used alone or in mixture, in completely randomized block design, with six replicates of five plants, totaling 30 plants per treatment. The experiments were carried out in a greenhouse with the single-cross hybrid AS 1565 in phenological stage of two to six expanded leaves, using an isolate of S. macrospsora from the same hybrid. The inoculum was deposited into the cartridge of plants at 48 hours after, 48 hours before and 10 days before fungicide applications for preventive, curative and eradicant action, respectively. The experiment was repeated twice. The data underwent analysis of variance (p<0.05), and the means of treatments were compared by using the Scott-Knott test (p<0.05). Severity was estimated at 21 days after inoculations. All fungicides significantly differed from the control treatment in the preventive, curative and eradicant action. For the preventive action, mean disease control was 85%. The mixture of triazoles plus strobilurins controlled, on average, 75% of the disease severity, while the isolated products such as strobilurins reduced it by 62%, benzimidazoles by 55% and triazoles by 38% for the curative action. The lowest control was obtained for the eradicant action, with mean reduction of 40.1% in the disease severity and no significant difference among fungicides.

Doses e épocas de aplicação de nitrogênio em cobertura na qualidade fisiológica de sementes de milho doce

The amount and timing of nitrogen application can favor seed quality, such as increasing protein content, which is an important constituent for embryo development. The objective of this study was to evaluate the physiological quality of sweet corn seeds collected from plants cultivated with different dosages and timings of nitrogen top-dressing applications. Seeds of the BR 400 variety (Super Sweet) were used obtained from plants submitted to dosages of 0, 40, 80 and 120kg ha -1 of N in two top-dressing applications (vegetative and reproductive stages). The weight of 100 grains, germination, first count of germination test, dry weight of normal seedlings from the germination test, seedling growth, cold test, accelerated aging, tetrazolium vigor and electric conductivity and emergency speed rate were determined. Data was submitted to an analysis of variance using the F-test at the 5% level and second degree regression analysis. The dosage and time of application of nitrogen top-dressing did not affect seed weight or the germination of sweet corn seeds. An increase of the N top-dressing dosage, applied in the vegetative stage reduced the length of the aerial part, the root and the whole seedling.

Análise Genética de Características Reprodutivas Na Raça Brahman

Aiming to establish selection criteria for the Brahman cattle in Brazil, the objective of this paper was to estimate genetic and environmental parameters for birth weight (BW), gestation length (GL) and scrotal circumference at 365 (SC365), 455 (SC455) and 550 (SC 550) days of age, and relative efficiency of indirect versus direct selection for these traits. Data were obtained from 15 851 animals belonging to 16 herds in six states, enrolled in a genetic breeding program. (Co)variance and heritability coefficients and genetic and environmental correlations between traits were estimated by restricted maximum likelihood (REML) under a multi trait animal model. The model included as fixed effects the contemporary group and the age of cow at calving as a covariate (linear and quadratic), and as random the direct genetic, the permanent environmental and residual effects. For BW and GL it was also considered the maternal genetic effect as random. Estimates of direct heritabilities were 0.36, 0.29, 0.55, 0.43 and 0.40 for BW, GL, SC365, SC455 and SC550, respectively. Genetic correlations between BW and GL, GL and SC365, GL and SC455, GL and SC550, SC365 and SC455, SC365 and SC550 and SC455 and SC550, were respectively 0.06, 0.13, 0.20, 0.13, 0.96, 0.98 and 0.99. The heritabilities estimates for all traits indicated these show enough additive genetic variability to respond favorably to selection. For sexual precocity, the best option would be SC365, due to the high value of heritability and to indirect selection at this age being more efficient than direct selection for PE455.

Substituição dos grãos secos de milho pela silagem de grãos úmidos de milho para vacas da raça holandesa em lactação

In order to evaluate the effects of replacement of dried corn (GSM) for silage moisture corn (HMCS) on production and milk composition were used five Holstein cows, primiparous with a mean of 112 days post delivery, confined in Tie Stall, for 70 days. We used five diets according to NRC to 17.5% CP (DM) and 2.4 Mcal / kg DM, the 40:60 ratio of roughage and concentrate containing soybean meal, sugar cane silage and hay and substitution levels of the GSM HMCS the following treatments: a) 0%, 2) 25%, 3) 50%, 4) 75% and 5) 100%. Milk production and dry matter intake (DMI) were recorded daily. The animals were milked daily 6:00 and 18:00 h, and milk samples collected from consecutive milkings of each experimental period of 14 days (four days of collection). The experimental design was a 5x5 Latin square and the data analyzed by the statistical program SAS. Body weight (508 kg), milk (23.6 kg), corrected milk (22.7 kg), DMI (17.13 kg) showed no significant difference, but the intakes of neutral detergent fiber (6.67 kg), and detergent acid (3.39 kg), feed efficiency for the production of milk (milk 1.41 kg / day) urea nitrogen (17.67 mg / dL) differ, thus indicating that HMCS is more efficient than GSM in the diet of dairy cows not alter the production and milk composition.

Caracterização genética do vírus da diarreia bovina detectada em bovinos do Sul de Minas Gerais, Brasil, persistentemente infectados

Isolates of bovine viral diarrhoea virus (BVDV) detected in serum samples of two persistently infected animals (PI) identified in a herd located in the southern state of Minas Gerais, Brazil, underwent genetic characterization trough partial nucleotide sequencing and analysis of the 5' Untranslated Region (5'UTR) of the viral genome. The isolates were characterized as belonging to genotype BVDV-1, subgenotype BVDV-1b. The results of this study suggest BVDV-1b as an agent of importance in the occurrence of bovine viral diarrhoea (BVD) in the herds of the region. Moreover, the genotypic characterization of isolates of BVDV helps to better understand the epidemiology of the disease, as the genetic variability of BVDV interferes in the serological tests and has implications for the use of vaccines, whose majority is produced only with reference strains of BVDV. Therefore, the investigation on the genetic diversity of BVDV existing in Brazil is required for the improvement of the disease prevention and control measures.

Consórcio de milho com Urochloa ruziziensis e os efeitos na cultura da soja em rotação

This work aimed to study the intercropping of corn and Urochloa ruziziensis cv. Common, regarding to vegetative growth and corn yield, capacity of production of forage dry matter, the infestation of weeds and the effect of this system of production in the soybean crop in rotation. Two forms of sowing (hand-sowing and on-line sowing) of U. ruziziensis, four amounts of seeds (200, 400, 600 e 800 points of cultural value, PCV = quantities of seeds x cultural value) and one treatment additional with the single corn were studied. The intercropping did not affect negatively the vegetative growth and corn yield when compared to the single corn. The sowing of 200 PCV of U. ruziziensis seeds, hand-sowed and on-line sowed to 22 days after of sowing of the corn was enough for the maintenance of adequate amount of straw on the soil. At the moment of the harvest of the corn, the dry matter of weed reduced with the increase of the amount of U. ruziziensis seeds and was bigger when the forager was hand-sowed. In the soybean crop in rotation, the density and dry matter of weed reduced linearly with the increase of the amount of U. ruziziensis seeds used in the first year of the research. The intercropping of corn and U. ruziziensis in the first year of the experiment benefited the plants population, plants height and yield of soybean when compared to the monoculture of corn in the same period.

Inoculação de sementes com bactéria diazotrófica e aplicação de nitrogênio em cobertura e foliar em milho

Considering the importance of nitrogen management and its biological fixation with diazotrophic bacteria, this study was carried out aiming to evaluate the agronomic performance of maize, in response to seed inoculation with Azospirillum brasilense and nitrogen application in side-dressing and leaf. The experiment was conducted in Selvíria, Mato Grosso of Sul State, Brazil, during the growing season 2010/2011, on a clayey Rhodic Haplustox (20° 20' S and 51° 24' W, with altitude of 340 m). Sixteen treatments were established with four replications, in randomized blocks with the combination of the factors A. brasilense (with and without inoculante), nitrogen rate (0 and 90 kg ha-1, in V5 growth stage) and urea leaf application (0, 4, 8 and 12%: application in V5 and V8 growth stage). The maize hybrid used was the DKB 390 YG®, sowed in the row spacing of 0.9 m. Parameters measured were productive and morphological components of culture and crop yield. Increase in maize yield by seed inoculation with A. brasilense was observed. The application of 90 kg ha -1 of nitrogen in side-dressing provided higher chlorophyll leaf index, stalk diameter and prolificacy, however, the yield not was increased. The application of urea leaf did not agronomic efficiency and, therefore, should not be used as the unique form of supply and alternative to nitrogen addition to crop.

Sistemas de manejo e atributos físico-hídricos de um Latossolo Vermelho cultivado com milho

The purpose of this experiment was to evaluate the hydro-physical attributes of the Red Oxisol cultivated with maize in Jaboticabal, São Paulo State, Brazil, under different systems of use and periods of adoption of managements. The experiment was arranged in a completely randomized design with split-plot arrangement, with six replications and the treatments were: six years of no-tillage system (SPD6), eight years of no-tillage system (SPD8), ten years of no-tillage system (SPD10), conventional tillage system (SPC) and an adjacent area of native forest (NF). The soil penetration resistance (PR), density, macroporosity, microporosity of the soil in layers of 0-0.05; 0.05-0.10 and 0.10-0.20 m, and the saturated hydraulic conductivity (Kθ) in 0.15 m depth were evaluated. It was found that the PR conditions were favorable for the cultivation to 0.20 m, indicating a structure preserved even after soil chiseling. Furthermore, the Kθ in the soil showed similar behavior between SPC and periods of SPD, although this was shown in a part of maize cycle, macroporosity values near 0.10 m3 m-3 and soil water tensions near 0.09 MPa.

Variação genética em progênies de jacaranda cuspidifolia mart. Utilizando o delineamento sistemático tipo leque

Knowledge of genetic variation in native tree species has helped direct strategies of genetic ex situ conservation, based on provenances and progenies tests. These tests use fixed spacing, not allowing evaluating the behavior of different progenies under this management variable. One way to evaluate simultaneously the genetic variation and different spacing in a small planting area is to use a systematic design. The aim of this study was to estimate the genetic variation and to evaluate its performance in Jacaranda cuspidifolia under different spacing. We used a progeny test in a systematic fan design, arranged in a system of 30 concentric rays, with one progeny per ray, randomly, at angles of 12°. The plants were arranged in rays in geometric progression of ratio 1.21, corresponding to nine for plant spacing: 1,95 m2; 2,86 m2; 4,18 m2; 6,12 m2; 8,96 m2; 13,12 m2; 19,21 m2; 28,13 m2; e 41,19 m 2 installed in Selvíria/MS. The traits height, height diameter of 30 cm to soil (DA3) and survival were evaluated at 12 and 24 months of age. Estimates of genetic parameters and spacing were evaluated using the procedure REML/BLUP (restricted maximum likelihood / best linear unbiased prediction). The progenies showed genetic variation, showing that the sample strategy to ex situ conservation was efficient. The species showed good adaptability inthe field and the best performance in treating five, equivalent to a 3 × 3 m spacing, with 8,96 m2;/plant for all traits. The fan systematic design permitted to evaluate in a small area the silvicultural behavior of J. Cuspidifolia plants in spacing varying from 2 to 42 m2/plant (5.000 to 238 trees/ha); which could hardly be evaluat by the traditional designs.

Características agronômicas e bromatolôgicas do milho submetido a adubações com potássio na produção de silagem

The aim was to evaluate levels and forms of application of potassium on the agronomic and alimentary characteristics of corn used for silage. The experiment was carried out at UNIFENAS during the agricultural year of 2008/2009. Fertilization at planting and sowing was performed manually using 120kg ha-1 P2O5 and 30kg ha-1 N, the potassium being applied according to the treatments. The experimental design used was of randomized blocks in a 4 x 2 factorial arrangement with four replications, using four amounts (0; 60; 90 and 120 kg ha-1) and two formsof application of K (100% at planting and 50% at sowing+50% coverage). The interaction between the factors of amount and forms of application of the potassium was not significant (p>0.05) for the variables studied: the main effect of each factor was then investigated. There was no effect (p>0.05) for K levels on the percentage of drymatter (DM) and bedded plants, DM and grain productivity and grain participation in the mass. The highest grain yield was obtained when using K at planting (p<0.05). High doses of potassium did not produce changes in DM, percentage of bedded plants, DM production, grain yield or grain percentage of the plant. The different levels and forms of application of potassium do not alter the alimentary characteristics of corn silage.

Efeito de dois sistemas de manejo do solo nas propriedades físicohídricas, desenvolvimento radicular e produtividade do milho irrigado

Corn cultivation is part of crop rotation used by irrigation farmers from the southwestern region of São Paulo state, Brazil, who use no-tillage soil management as a kind of sustainable use of soil. The effect of this conservative practice on physical and hydrical properties of the soil, root development and corn crop yield compared to the conventional management was the objective of this work. The experiment was held at the Buriti-Mirim Farm, Angatuba, SP, Brazil, using an irrigated area with a center pivot system and two types of soil management: conventional and no-tillage systems. Although the no-tillage management had higher soil density and less water availability, no significant difference was found for both management systems concerning soil resistance to penetration, root development and crop yield. In both systems of soil management, 90% of roots were concentrated in the first 0-20cm of soil layer.

Densidades e arranjos populacionais de milho e componentes agronômicos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)