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The integration of aerial monitoring, utilizing both unmanned aerial vehicles (UAVs) and satellites, alongside sophisticated machine learning algorithms, has witnessed a burgeoning prevalence within contemporary agricultural frameworks. This study endeavors to systematically explore the inherent potential encapsulated in high-resolution satellite imagery, concomitantly accompanied by an RGB camera seamlessly integrated into an UAV. The overarching objective is to elucidate the viability of this technological amalgamation for accurate maize plant height estimation, facilitated by the application of advanced machine learning algorithms. The research involves the computation of key vegetation indices—NDVI, NDRE, and GNDVI—extracted from PlanetScope satellite images. Concurrently, UAV-based plant height estimation is executed using digital elevation models (DEMs). Data acquisition encompasses images captured on days 20, 29, 37, 44, 50, 61, and 71 post-sowing. The study yields compelling results: (1) Maize plant height, derived from DEMs, demonstrates a robust correlation with manual field measurements (r = 0.96) and establishes noteworthy associations with NDVI (r = 0.80), NDRE (r = 0.78), and GNDVI (r = 0.81). (2) The random forest (RF) model emerges as the frontrunner, displaying the most pronounced correlations between observed and estimated height values (r = 0.99). Additionally, the RF model’s superiority extends to performance metrics when fueled by input parameters, NDVI, NDRE, and GNDVI. This research underscores the transformative potential of combining satellite imagery, UAV technology, and machine learning for precision agriculture and maize plant height estimation.

The model selection stage has become a central theme in applying the additive main effects and multiplicative interaction (AMMI) model to determine the optimal number of bilinear components to be retained to describe the genotype-by-environment interaction (GEI). In the Bayesian context, this problem has been addressed by using information criteria and the Bayes factor. However, these procedures are computationally intensive, making their application unfeasible when the model's parametric space is large. A Bayesian analysis of the AMMI model was conducted using the Reversible Jump algorithm (RJMCMC) to determine the number of multiplicative terms needed to explain the GEI pattern. Three a priori distributions were assigned for the singular value scale parameter under different justifications, namely: i) the insufficient reason principle (uniform); ii) the invariance principle (Jeffreys' prior) and iii) the maximum entropy principle. Simulated and real data were used to exemplify the method. An evaluation of the predictive ability of models for simulated data was conducted and indicated that the AMMI analysis, in general, was robust, and models adjusted by the Reversible Jump method were superior to those in which sampling was performed only by the Gibbs sampler. In addition, the RJMCMC showed greater feasibility since the selection and estimation of parameters are carried out concurrently in the same sampling algorithm, being more attractive in terms of computational time. The use of the maximum entropy principle makes the analysis more flexible, avoiding the use of procedures for correcting prior degrees of freedom and obtaining improper posterior marginal distributions.

Abstract Background The study of cold tolerance in maize seeds and seedlings through physiological quality assessments, as well as the genetic control associated with this trait, allows an early characterization of genotypes. Here we studied the genetic control for cold tolerance during the germination process in maize seeds and genes influenced by this stress. Results Six maize lines were used, three classified as tolerant and three as susceptible to low germination temperature. A field was developed to produce the hybrid seeds, in a partial diallel scheme including the reciprocal crosses. For the expression analysis, seeds from two contrasting lines were used, as well as their hybrid combination and their reciprocal crosses, on dried and moistened seeds at 10 °C for 4 and 7 days. It was evaluated the catalase (CAT) and esterase (EST) enzymes, heat-resistant proteins and the genes Putative stearoyl-ACP desaturase (SAD), Ascorbate Peroxidase (APX), Superoxide Dismutase (SOD) and Mitogen Activated Protein Kinase (ZmMPK5). The estimated values ​​for heterosis, general and specific combining abilities and reciprocal maternal and non-maternal effects were carried out and it showed that there is heterosis for germination at low temperatures, also the non-additive genes were more important and there was a reciprocal effect. Conclusions There is a greater expression of the CAT and EST enzymes in moistened seeds at seven days and there is less expression of heat-resistant proteins and the SAD gene at seven days of moistening. Also, there are variations in the expression of the APX, SOD and ZmMPK5 genes in dried and moistened seeds, as well as among the genotypes studied.

ABSTRACT: The development and recommendation of single cross maize hybrids (SH) to be used in extensive land areas (mega-environments), and in different crop seasons requires many experiments under numerous environmental conditions. The question we asked is if the data from these multi-environment experiments are sufficient to identify the best hybrid combinations. The aim of this study was to critically analyze the phenotype data of experiments of yield, established by a large seed producing company, under a high level of imbalance. Data from evaluation of 2770 SH were used from experiments conducted over four years, involving the first and second crop seasons, in 50 locations of different years and regions of Brazil. Different types of analysis were carried out and genetic and non-genetic components were estimated, with emphasis on the different interactions of the SH with the environments. Results showed that the coincidence of common hybrids in these experiments is normally small. The estimates of the correlations between of the hybrids coinciding in the environments two by two is of low magnitude. The hybrid × crop season interaction was always expressive; however, the interactions of hybrids and other environmental variables were also important. Under these conditions, alternatives were discussed for making with the information obtained from the experiments, can be more efficient on the process to obtain new hybrids by companies.

Abstract: The chemical treatment of corn seeds is widely adopted for protecting crops at the early stages. However, some molecules interfere in the quality of seeds, especially when stored, by accelerating their deterioration. The objective of this work was to investigate the influence of insecticides on the enzymatic expression and quality of corn seeds subjected to storage. Seeds of the hybrids 2B647PW and SHS4070 were subjected to four different chemical treatments (standard treatment, standard + clothianidin, standard + thiamethoxam, and standard + fipronil) and stored for different periods (0, 3, 6, and 9 months). The quality evaluation included the germination test, first germination count, cold test, and health test. The expression of the enzymes α-amylase, esterase, superoxide dismutase, catalase, and alcohol dehydrogenase were determined by the gel electrophoresis technique. The insecticides clothianidin, thiamethoxam, and fipronil reduce the physiological quality of the seeds of hybrid 2B647PW after nine months of storage. The treatment of seeds with the insecticides clothianidin, thiamethoxam, and fipronil reduces the expression of α-amylase, superoxide dismutase, and catalase enzymes after nine months of storage. The enzymes α-amylase, superoxide dismutase, catalase, and alcohol dehydrogenase are good quality markers for hybrid corn seeds.

ABSTRACT The choice of germplasm is one of the most important phases of a genetic improvement program to the fact that it is the initial development stage of superior hybrids. Hence, the objectives of this study were to obtain the estimates of m+a and d, and inbreeding depression for grain yield and plant height traits, for cultivars lacking this information, and thus to predict the potential of maize hybrids for the extraction of lines. The F1 and F2 generations of 12 maize hybrids were tested at two sites, during the crop years of 2017-18 and 2018-19, accounting for four environments. Both the generations were evaluated in contiguous experiments in randomized blocks design with three and two repetitions during the years 2017-18 and 2018-19, respectively. The data on plant height and grain yield were collected, per plot, from both the generations, utilizing which, the m+a and d mean components were estimated. The effects of dominance had greater importance for the character grain yield. The most promising hybrids for extraction of lines were AG1051, AG8025, BG7046, DKB455, and OMEGA due to their greater estimates of m+a. The hybrids AG8025 and BG7046 were associated with high values of m+a and grain yield. For the plant height trait, there was a greater contribution of additive effects. Therefore, greater inbreeding depression was observed for the grain yield trait when compared to the height of the plant.

Abstract: The aim of this study was to investigate the effect of treatment with insecticides and fungicides on the physiological quality of corn seeds, classified in sizes, in different periods of storage. Seeds of the hybrid BM915 PRO, classified in two sizes (CH20/64 and CH24/64), were treated with a mixture of carbendazim + thiram (Derosal Plus®), pirimiphos methyl (Actellic®), deltamethrin (K-obiol®), and water (standard treatment). In addition to the standard treatment adopted by the company, treatments with clothianidin (Poncho®), thiamethoxam (Cruizer®), and fipronil (Shelter®) were added to the spray mixture. The seeds were stored in a non-climate-controlled environment in multi-ply paper packages. The physiological quality of the seeds was evaluated every ninety days over a period of 270 days by the germination test, cold test, and accelerated aging. Sanitary quality was also evaluated through the Blotter test. The physiological quality of seeds of the hybrid BM915 PRO is maintained up to ninety days of storage, regardless of the chemical treatment used and the size of the seeds. The addition of the insecticide to the standard treatment used in chemical seed treatment does not affect the action of the fungicides on the fungi in the seeds.

Nitrogen is the most required and complex management element in maize crop, promoting the highest responses in crop yield. The objective of this work was to verify the effect of different N sources on topdressing in minimum tillage and conventional tillage systems on the agronomic performance of the Pioneer 32R22YHR single cross and on the severity of common rust disease. Two experiments were carried out in a randomized block design (DBC) in the 2013/14 crop in minimum tillage and conventional tillage systems. The treatments were: control without nitrogen, ammonium sulfate, urea, ammonium nitrate, a physical mixture of nitrate (70%) and ammonium sulfate (30%) and a chemical mixture of these same sources in the same proportion just explained. Nitrogen sources had no significant effect on plant height, ear insertion height, ear prolificacy, grain yield and leaf severity of common rust, regardless of the sowing system. Under conventional tillage, the plants presented higher plant height, ear insertion and grain yield. There was no effect of sowing systems on prolificacy. With the exception of nitrogen free treatment, for all others, the severity of common rust was higher in minimum tillage system.

ABSTRACT Knowing genes related to water deficit is a valuable tool to assist and accelerate the selection process of maize genotypes more adapted to drought conditions. Therefore, this work aimed to evaluate genes expression related to tolerance to water deficit in maize lines, using proteomic and transcriptomic analyses. Two lines previously classified as tolerant (91-T) and non-tolerant (57-NT) to low water availability were used. Dried seeds, ears tips, and seedlings (collected at three, five, and seven days after sowing) of the two maize lines (91-T and 57-NT) were used in proteomic analyses. Seedlings were subject to two contrasting water-availability conditions (70% and 10% of the water retention capacity). The expression of catalase, peroxidase, and esterase enzymes and heat-resistant proteins were evaluated by electrophoresis. Dried seeds, ears tips, and seedlings (collected at seven days after sowing, subject to two contrasting water-availability conditions) of two maize lines (91-T and 57-NT) were used in the transcriptomic analyses. The expression of genes associated with tolerance to low water availability (ZmPP2C, ZmLEA3, and AOX2) was evaluated by the qRT-PCR technique. Results revealed that catalase, peroxidase, and esterase enzymes had a higher expression on the ears tips of the 91-T line. The expression of catalase and esterase enzymes reduced in seven-day-old seedlings in the two lines analyzed. Heat-resistant proteins had greater activity on the dried seeds of the 91-T line. The AOX2 gene was identified as a potential marker for the selection of maize genotypes tolerant to water deficit.

In Brazil, with the constant use of concentrated NPK fertilizers, sulfur became a limiting nutrient for corn plant growth and development. This research aimed to evaluate the efficiency of elemental sulfur coating the granule of fertilizer, compared with the sulfur of ammonium sulfate associated to soluble fertilizers based on NPK. The hybrid-corn DKB390 was evaluated under a completely randomized design in a factorial scheme 3x6 (three fertilizers × six phenological stages) with three replications. A soil under corn monoculture was used. Three types of formulated fertilizers (NPK) associated with sulfur (ammonium sulfate or elemental sulfur) and the control without S was used. The accumulation of the shoots and root dry matter, chlorophyll and sulfur in leafs were evaluated. The data were collected at stages: 6 leafs, 10 leafs, 14 leafs, tasselling, flowering and physiological maturity. The used fertilizers provided differences on the shoot dry matter and ion the sulfur accumulation in leafs. The sulfur accumulation in corn leafs was similar among the elemental sulfur and the ammonium sulfate treatments. Elemental sulfur provided superior results in comparison to the fertilizer without sulfur and was similar to the fertilizer with ammonium sulfate.

The objective of this study was to evaluate gene expression related to water deficit tolerance in maize lines. For this, lines previously classified as tolerant (91-T and 32-T) and non-tolerant (24-NT and 57-NT) to water deficit were used. The seeds of the four lines were evaluated for emergence and emergence speed index, and the seedlings were evaluated for root and shoot length under two conditions of water availability (70 and 10% substrate water retention capacity). In transcript analysis, the expression of several genes associated with water deficit tolerance, ZmDBP3, ZmALDH9, ZmAN13, and ZmDREB2A, was evaluated by qRT-PCR for the 91-T and 57-NT lines. It can be concluded that soil water deficiency did not reduce root development. However, the shoot length was significantly lower under dry conditions. Through transcript analysis, the genes ZmDBP3 and ZmAN13 were identified as potential markers for the early selection of maize lines tolerant to water deficit.

Maize breeding programs conduct multi-environment trials every year to assess the performance of new cultivars in pre-releasing tests. The data are combined across sites and seasons to perform a joint analysis in order to obtain information that will help breeders to select the best cultivars for different environments. Beyond this, it is essential to understand the different factors that can hamper the selection and genetic progress (i.e., genetic variability, selection intensity and genotype-by-environment interactions). In this study, the genetic progress (GP) was estimated and the adaptability and stability of 81 maize genotypes were evaluated in a series of trials for the value of cultivation and use (VCU) between the 2010/11 and 2014/15 growing seasons. The genotypes were composed of open-pollinated varieties, topcross hybrids, intervarietal hybrids, and single, double and three-way cross hybrids and were assessed in 117 environments in the central region of Brazil, from which 22 presented environmental stresses. For grain yield, an annual GP of 331.5 kg ha-1 was observed, thus showing efficiency in the selection of superior cultivars. Additionally, it was observed that some low-cost seed cultivars showed yield potential, adaptability and stability estimates that were compatible with commercial hybrids, thus making them quite attractive for cultivation in environments with or without abiotic stresses.

Saccharine sorghum is an excellent option for ethanol production under industrial and agronomic perspectives, due to high green matter production and succulent stalks with fermentable sugars. The aim of this work was to evaluate the harvesting season and plants population effect over the ethanol and fodder production from sweet sorghum culture BRS 506. The experiment was installed in November 2012, at (CDTCA/UFLA), located in Lavras (MG). The experimental design was in randomized blocks, with 3 repetitions, factorial scheme 4 x 4 (4 populations: 70, 100, 130 and 160 thousand plants ha-1 ; 4 harvesting seasons: flowering (0 days after flowering (DAF), 10 DAF, 20 DAF and physiological maturity at 40 DAF). The variables evaluated at harvesting: green matter weight (GM), dry matter weight (DM), juice volume (JV), total soluble solids (ºbrix), total reducing sugars (TRS) and brix tonnes per hectare (TBH). The populations increase provided the highest JV and it has not affected other variables. The characteristics were influenced by the harvesting seasons. The harvesting season at 40 DAF provided the highest ºbrix. The ºbrix and the TRS showed linear growth with an increase after flowering for plants harvesting. The highest productivities (GM, DM, JV and TBH) were obtained close to 17, 22, 17 and 14 DAF, respectively, favoring higher fodder and ethanol production in these stages.

ABSTRACTArtificial chromosome duplication is one of the most important process in the attainment of doubled haploids in maize. This study aimed to evaluate the induction ability of the inducer line KEMS in a tropical climate and test the efficiency of the R1-Navajo marker by flow cytometry to evaluate two chromosome duplication protocols and analyze the development of the doubled haploids in the field. To accomplish this goal, four genotypes (F1 and F2 generations) were crossed with the haploid inducer line KEMS. The seeds obtained were selected using the R1-Navajo marker and subject to two chromosome duplication protocols. Duplication was confirmed using flow cytometry. The percentages of self-fertilized plants after duplication as well as the quantities of doubled haploid seeds obtained after the self-fertilization processes were analyzed. It was observed that the germplasm influences haploid induction but not the duplication rates of the tested protocols. Protocol 2 was more efficient for the duplication of haploids, in the percentage of self-fertilized plants after duplication, and in the attainment of doubled haploid lines. Moreover, the haploid inducer line KEMS can produce haploids in a tropical climate. Other markers, in addition to the R1-Navajo system, should be used in the selection of haploid seeds.

The development of adapted cultivars to nitrogen stress conditions is shown as an ecologically sustainable option to ensure higher yields in low input agricultural systems. This study aimed to evaluate the NUE in tropical maize (Zea mays L.) populations to forage production in the south of the State of Tocantins. Two experiments were done corresponding to low and high N availability sown on November 21, 2009. Twenty four maize populations and a commercial cultivar BR 106 were used in the experiments. The experimental design was a randomized block with two replicates. Plant height, ear height, ear participation in plant total green mass, ear green mass; plant green mass without ear, total green mass and NUE in forage production were evaluated. Through Moll methodology differences among populations for nitrogen use efficiency were found, however these differences weren’t found on Fischer methodology. Populations 12-4, 1-3, 12-6, 12-5, 26-1, 15-2, 25-2 and 1-5 are considered efficient in nitrogen use. The populations 12-6, 12-5, 12-4, 1-3, 1-4, 1-5 and 15-2 are the best populations to use in high and low N environment, combining great production of green mass and being efficient in N use.

Early characterization of genotypes, through the previous assessment of physiological quality of their seeds and their enzymatic systems, can provide parameters capable of aiding in the selection of new maize cultivars tolerant to water stress. Thus, this study was aimed at assessing seed performance of five different maize lines subjected to four different water stress levels. The physiological quality of seeds germinated under the osmotic potentials of 0.0, -0.3, -0.6 and -0.9 MPa was assessed by germination test, number of strong normal seedlings and T50, as well as by the expression of the isozymes superoxide dismutase (SOD), catalase (CAT), glutamate oxaloacetate transaminase (GOT), esterase (EST), malate dehydrogenase (MDH), alcohol dehydrogenase (ADH), and of heat-resistant proteins. The osmotic potential of -0.9 MPa affected the physiological quality and vigor of seeds of all maize lines assessed. The highest values for the germination percent, in the lowest osmotic potentials assessed, were found in the seeds of line 63. However, seeds of line 91 were superior in regard to vigor. Increased expression of the enzymes SOD and CAT, considered as enzymes of the antioxidant system, was observed in seeds of lines 44 and 91. Thus, line 91 was considered as promising for tolerance to water stress.

With the growth in the transgenic market, fast and economically viable methodologies are necessary for undertaking transgene detection tests, both for identification of contamination in seeds and in grain. Seeds from commercial conventional GNZ 2004, and transgenic VT-Pro (MON89034), Roundup Ready (NK603) and Herculex (TC1507) maize cultivars were used. In order to simulate different levels of contamination, the transgenic seeds were mixed with conventional seeds at levels of 0.2%, 0.4%, 1.0% and 1.6% for VT-Pro, and 0.2%, 0.5%, 0.8% and 1.2% for Roundup Ready and Herculex. The lateral flow membrane strip test was performed in the whole seed, endosperm and embryo. For evaluation of the specificity of the technique in detection of the TC1507 event by means of the conventional PCR technique, seeds of the commercial maize hybrid GNZ 2004 were used as negative control, and the maize hybrid 2B655Hx as positive control. In order to simulate different levels of contamination, transgenic seeds were mixed with conventional seeds at the levels of 10%, 5%, 1%, 0.5% and 0.1%. Seeds from each sample were crushed, and then DNA extraction was performed by the CTAB 2% method. Using the immunochromatographic strip, it was possible to evaluate the expression of proteins related to the VT-Pro, Roundup Ready and Herculex events when whole seeds were used at the 0.2% level of contamination, whereas by the conventional PCR technique, it was possible to detect the TC1507 event in samples with 1% contamination.

Este trabalho foi realizado com o objetivo de avaliar os efeitos da aplicação de fungicida, no controle da Cercosporiose e da Mancha-Branca do milho, e suas consequências na produtividade de grãos e na incidência de grãos ardidos, além de estabelecer a relação existente entre a produtividade de grãos e a severidade dessas doenças. Dois experimentos distintos (com Azoxystrobina + Cyproconazole e tratamento controle) foram conduzidos em três locais, no ano agrícola de 2007/2008. Utilizaram-se 12 híbridos comerciais de milho, que foram avaliados em delineamento de blocos casualizados, com três repetições. Foram realizadas cinco avaliações da severidade das doenças Cercosporiose e Mancha-Branca, por meio de escala de notas, variando de 1 (altamente resistente) a 9 (altamente susceptível). Estimou-se a área abaixo da curva de progresso da doença (AACPD). A aplicação de fungicida é eficiente no controle de doenças foliares e na redução da incidência de grãos ardidos, além de proporcionar 12% de aumento na produtividade de grãos, em relação à do tratamento controle. As doenças foliares Cercosporiose e Mancha-Branca reduzem a produtividade de grãos de milho e essa redução é maior quando as doenças ocorrem mais precocemente. A Cercosporiose provoca maior redução na produtividade de grãos, quando comparada com a Mancha-Branca.

The development of homozygous breeding lines in maize may be accelerated through the use of haploids. Thus, the obtaining and prior identification of haploids generated by the haploid inducer lines is an important factor. The purpose of this study was to identify haploids by flow cytometry and to correlate the nuclear DNA content to the morphological and morphometric traits of the seeds that gave rise to them. In addition, molecular markers were used to confirm the androgenetic nature of the haploid. The seeds obtained were derived from the cross between the inbred line W23 and the commercial hybrid P30F90. Among these seeds, a group was selected, putative haploids, whose embryo was white and the pericarp purplish. This group, consisting of 330 seeds, was characterized based on seed morphology, seed morphometry and nuclear DNA content. Flow cytometry analyses identified four haploids, and all of them were small size plants and had brittle leaves. The weight, length, thickness and width of the haploid seeds were very variable indicating that morphometric traits do not constitute reliable data for visual selection of haploid seeds. Based on results, the inbred line W23 induced haploid maize even under tropical conditions. Microsatellite molecular markers (SSR) proved to be efficient, confirming the androgenetic trait of the haploids.O desenvolvimento de linhagens homozigotas em milho pode ser acelerado por meio do uso de haploides. Para isso, a obtenção e identificação prévia dos haploides gerados pelas linhagens indutoras de haploidia é um fator importante. O objetivo do trabalho foi identificar haplóides por meio de citometria de fluxo para então correlacionar o conteúdo de DNA nuclear aos caracteres morfológicos e morfométricos das sementes que os originaram. Além disso, marcadores moleculares foram utilizados para confirmar a natureza androgenética do haploide. As sementes obtidas foram provenientes do cruzamento entre a linhagem W23 e o híbrido comercial P30F90. Dentre essas sementes, foi selecionado um grupo, possíveis haplóides, cujo embrião era branco e o pericarpo arroxeado. Esse grupo, constituído de 330 sementes, foi caracterizado quanto à morfologia, morfometria e conteúdo de DNA nuclear. As análises de citometria de fluxo identificaram quatro haploides, e todos eles apresentaram porte reduzido e folhas quebradiças. Os pesos, comprimentos, espessuras e larguras das sementes haplóides variaram muito, indicando que caracteres morfométricos não são eficientes para a seleção visual de haploides. Baseado nos resultados, a linhagem W23 induz haplóides em milho mesmo em condições tropicais. Os marcadores moleculares microssatélites (SSR) mostraram-se eficientes, comprovando o caráter androgenético dos haploides.

The physiological quality of maize seeds is affected by the genotype. Thus, the study of expression of genes associated with this characteristic is important in the genotype selection process in breeding programs. The aim of this research was to study the expression of amylase enzymes associated with physiological quality of maize seeds with different genotypes and seed sizes. We further sought to assess the expression of these enzymes in dry and soaked seeds The experiment was conducted in the experimental area and the Central Seed Laboratory of the Department of Agriculture of the Universidade Federal de Lavras. Seeds of four maize inbred lines were used, classified in two sizes. The physiological quality of the seeds was evaluated by means of germination, seedling emergence, seedling emergence speed index and accelerated aging test. Expression of the alpha amylase enzyme was evaluated by the electrophoresis technique and expression of the alpha amylase B73, alpha amylase (LOC542522) and beta amylase 5 (amyb5) genes was studied by the qRT-PCR technique in dry and soaked seeds of the inbred lines. There is differentiated expression of amylase enzymes in maize seeds of inbred lines with different levels of physiological quality. higher expression of amylase enzymes is observed in soaked maize seeds. The expression of transcripts is higher in smaller as wellas in soaked maize seeds of inbred lines.A qualidade fisiológica de sementes de milho é influenciada pelo genótipo. Assim, o estudo da expressão de genes associados a essa característica é importante no processo de seleção de genótipos em programas de melhoramento. O objetivo neste trabalho foi estudar a expressão das enzimas amilases associadas à qualidade fisiológica de sementes de milho, de diferentes genótipos e tamanhos de sementes. Objetivou-se ainda avaliar a expressão dessas enzimas em sementes secas e embebidas. O experimento foi conduzido em área experimental e no Laboratório Central de Sementes do Departamento de Agricultura da Universidade Federal de Lavras. Foram utilizadas sementes de quatro linhagens de milho, classificadas em dois tamanhos. A qualidade fisiológica das sementes foi avaliada por meio dos testes de germinação, emergência de plântulas, índice de velocidade de emergência de plântulas e envelhecimento artificial. A expressão da enzima -amilase foi avaliada pela técnica de eletroforese e a expressão dos genes alpha amylase B73, alpha amylase (LOC542522) e beta amylase 5 (amyb5), foi estudada pela técnica de qRT-PCR em sementes secas e embebidas das linhagens. Há expressão diferenciada das enzimas amilases em sementes de linhagens com diferentes níveis de qualidade fisiológica. Maior expressão das enzimas amilases é observada em sementes de milho de menor tamanho e embebidas.

The objectives of this study were to evaluate corn cultivars for efficiency in the absorption and use of nitrogen (N) levels of efficiency through the use of nitrogen in contrasting levels of this nutrient in the greenhouse. The experiment was carried out in a greenhouse and the experimental design was in randomized blocks, with 20 treatments and four replicates, in a 10 x 2 factorial arrangement. All 10 maize cultivars were represented by local varieties and commercial hybrids, and the applied N levels were 100 and 400 mg dm-3. Plots were represented by 8L pots containing 4 plants each, which were harvested in phenological stage V8. The evaluated characteristics were dry matter weight and N level of shoot and roots. The nutritional efficiency of cultivars was also evaluated. The studied cultivars had distinct characteristics concerning N use and absorption efficiency in environments of high and low nitrogen levels. The contrasting N levels allowed the occurrence of differences needed to distinguish the most efficient cultivars. Genotypes efficient for N use and responsive to its application can be selected based on the indexes used in this work. Os objetivos deste trabalho foram avaliar cultivares de milho quanto à eficiência na absorção e uso de nitrogênio (N) através de índices de eficiência de utilização de nitrogênio, em níveis contrastantes desse nutriente em ambiente de casa de vegetação. O experimento foi conduzido em casa de vegetação e o delineamento experimental utilizado foi o de blocos casualizados, com 20 tratamentos e quatro repetições, dispostos em um esquema fatorial de 10 x 2. As 10 cultivares de milho foram representadas por variedades locais e híbridos comerciais e as doses de N aplicadas foram de 100 e 400 mg dm-3. As parcelas foram representadas por vasos de 8 L, os quais continham 4 plantas por vaso, sendo colhidas no estádio fenológico V8. As características avaliadas foram o peso de matéria seca e teor de N da parte aérea e raízes. Também foi avaliada a eficiência nutricional das cultivares. As cultivares estudadas apresentaram características distintas quanto à eficiência no uso e absorção de N nos ambientes com alto e baixo nível de nitrogênio. Os níveis contrastantes de N utilizados permitiram que ocorressem diferenças necessárias para distinguir as cultivares mais eficientes. Genótipos eficientes para uso de N e responsivos a sua aplicação podem ser selecionados pelos índices utilizados nesse trabalho.

New proposals for models and applications of prediction processes with data on molecular markers may help reduce the financial costs of and identify superior genotypes in maize breeding programs. Studies evaluating Genomic Best Linear Unbiased Prediction (GBLUP) models including dominance effects have not been performed in the univariate and multivariate context in the data analysis of this crop. A single cross hybrid construction procedure was performed in this study using phenotypic data and actual molecular markers of 4,091 maize lines from the public database Panzea. A total of 400 simple hybrids resulting from this process were analyzed using the univariate and multivariate GBLUP model considering only additive effects additive plus dominance effects. Historic heritability scenarios of five traits and other genetic architecture settings were used to compare models, evaluating the predictive ability and estimation of variance components. Marginal differences were detected between the multivariate and univariate models. The main explanation for the small discrepancy between models is the low- to moderate-magnitude correlations between the traits studied and moderate heritabilities. These conditions do not favor the advantages of multivariate analysis. The inclusion of dominance effects in the models was an efficient strategy to improve the predictive ability and estimation quality of variance components.

ResumoO objetivo deste trabalho foi avaliar híbridos de milho oriundos de empresas sementeiras do Brasil, com e sem a inoculação dos fungos Fusarium verticilioides, Stenocarpella maydis e Stenocarpella macrospora, em dois sistemas de cultivo, convencional e sistema de semeadura direta e em dois anos agrícolas e verificar a associação com parâmetros químicos e bioquímicos, que possam estar diretamente relacionados à resistência aos fungos. As características avaliadas foram à produtividade de grãos, a porcentagem de grãos ardidos, os teores de ácidos graxos, as proteínas resistentes ao calor e a atividade da enzima lipoxigenase. A significância do contraste entre os híbridos considerados resistentes versus os híbridos considerados susceptíveis, para produtividade de grãos e porcentagem de grãos ardidos evidência a existência de genótipos com maior resistência os fungos F. verticilioides, S. maydis e S. macrospora. A produtividade de grãos e a porcentagem de grãos ardidos foram influenciadas pelo tipo de híbrido, pelas safras agrícolas e pelas inoculações artificiais, sendo mais pronunciada no sistema de plantio direto. Não há associação entre a produtividade de grãos e porcentagem de grãos ardidos o que evidencia que as perdas provocadas pela incidência de grãos ardidos em milho não são de caráter quantitativo. Há diferenças nos teores de ácidos graxos linoléico entre os grupos de híbridos estudados, sendo maiores os valores obtidos no grupo de híbridos considerados resistentes ao complexo grãos ardidos. Com base na concentração de frações de proteínas resistentes ao calor, foi possível verificar bandas específicas presentes nos híbridos considerados resistentes aos fungos causadores do complexo grãos ardidos, mais especificamente de peso molecular de 50 kDa. Os perfis eletroforéticos para a lipoxigenase revelam uma maior intensidade de bandas para os híbridos resistentes aos fungos causadores de grãos ardidos em milho.

O objetivo desse trabalho foi selecionar o melhor meio de cultura e a temperatura de incubação para germinação dos grãos de pólen e determinar o horário de coleta e a metodologia de secagem destes. Os ensaios foram realizados no Laboratório Central de Sementes e na área experimental do Departamento de Agricultura da UFLA. Foram testados seis meios de cultura e duas temperaturas para incubação de grãos de pólen (25 e 30oC) coletados em diferentes horários do dia (9, 14 e 16 horas). Avaliou-se também a tolerância do grão de pólen à dessecação usando dois sais (cloreto de sódio e de lítio). Para avaliar a germinação, os grãos de pólen foram colocados em placas de petri com meio de cultura na temperatura adequada por duas horas. Para o teste do corante utilizado para avaliar a viabilidade, os grãos de pólen foram submetidos a lâminas com corante Alexander e avaliados com auxílio de microscópio óptico. Maiores valores de germinação dos grãos de pólen são observados em meio de cultura contendo 10% de sacarose, 0,03% de ácido bórico e 0,15% de cloreto de sódio a 25ºC e quando a coleta é realizada às 9 horas. Grãos de pólen de milho perdem a viabilidade na medida em que são dessecados.

O objetivo deste trabalho foi estimar o fluxo gênico em milho transgênico com resistência a insetos, em lavouras comerciais. Amostras de grãos foram coletadas em lavouras com milho convencional e transgênico, nos municípios de: Itumirim, Uberlândia, Paracatu e Tupaciguara, MG; Itapetininga e Pedrinhas, SP; e Assaí e Ponta Grossa, PR. As amostras foram coletadas em lavouras de milho convencional, a partir de 5 m de distância da fonte com o milho transgênico. Foram coletadas dez espigas de plantas individuais por ponto, em quatro repetições, no total de 40 espigas para cada distância amostrada. As análises de fluxo gênico foram realizadas por meio da técnica de reação em cadeia da polimerase (PCR) em tempo real. Em média, 82% da fecundação cruzada ocorreu nos primeiros 30 m. Em Itapetininga, SP, foram observadas as maiores taxas de fecundação cruzada - acima de 10% até a distância de 50 m -, porém, inferiores a 1% na distância de 100 m. O isolamento de 20 m, com dez linhas de bordadura, não é suficiente para garantir taxas de fecundação cruzada inferiores a 1%.

The objective of this experiment was to characterize the dry matter production of vegetative components (stalk, leaf, husk, and cob) and reproductive components (grain) of the corn plant according to planting time and the grain maturity stage. Eight corn hybrids with different agronomic characteristics were used to carry out the experiments. Two experiments were performed with planting undertaken on 11/11/2007 and 12/12/2007 under a conventional tillage system. The eight corn cultivars were harvested at three grain maturity stages, half milk line, three quarters milk line and black layer. An 8 × 3 factorial (eight hybrids and the three cutting times) randomized blocks design was used, with three replications. Individual analysis of variance was performed for each experiment. Then joint analysis of variance was performed involving the two planting times. The means were grouped and the hybrids used as replications to characterize the components. Delay in planting significantly reduced the dry matter productivity of the whole plant; however, it did not reduce its degradability. The greatest dry matter productivity obtained was that of grain, followed by stalk, leaf, husk and cob. The vegetative components, leaves and husk, lose quality with delay in planting. The leaf is the vegetative component of highest quality, while the cob is the worst. Delay in planting increases the neutral detergent fiber content of the stalk, husk and cob.

This work was carried out in order to evaluate the effects of fungicides on the control of maize gray leafspot and maize white spot and its implications on the grain yield and kernel rot, and also to establish the relationshipbetween grain yield and disease severity. Twelve commercial single cross hybrids were evaluated in a randomizedblock design with three replications. Five evaluations of disease severity were performed using a visual symptomsscale, ranging from 1 (highly resistant) to 9 (highly susceptible). Fungicide application was effective in the control ofmaize leaf diseases, and the reduced incidence of kernel rot provided on average 12% increased grain yield comparedto the control treatment. Maize gray leaf spot and maize white spot reduced maize grain yield, and this reduction wasgreater when diseases occurred earlier. Maize gray leaf spot caused higher decrease in grain yield than white spot.

The main objectives of hybrid development programs include incorporating genetic resistance to diseases and increasing grain yield. Identification of Quantitative Trait Loci (QTL) through the statistical analysis of molecular markers allows efficient selection of resistant and productive hybrids. The objective of this research was to identify QTL associated with resistance to gray leaf spot and for grain yield in the germplasm of tropical corn. We used two strains with different degrees of reaction to the disease; the genotypes are owned by GENESEEDS Ltda, their F1 hybrid and the F2 population. The plants were evaluated for gray leaf spot resistance, for grain yield and were genotyped with 94 microsatellite markers. Association of the markers with the QTL was performed by single marker analysis using linear regression and maximum likelihood analysis. It was observed that the additive effect was predominant for genetic control of resistance to gray leaf spot, and the dominant effect in that of grain yield. The most promising markers to be used in studies of assisted selection are: umc2082 in bins 4.03 and umc1117 in bins 4.04 for resistance to gray leaf spot; for grain yield umc1042 in bins 2.07 and umc1058 in bins 4.11.A incorporação de resistência genética a doenças e o aumento na produtividade de grãos estão entre os principais objetivos dos programas de desenvolvimento de híbridos. A identificação de locos de caracteres quantitativos (QTL) por meio de análises estatísticas associadas a marcadores moleculares possibilita a rápida obtenção de híbridos resistentes e produtivos. Nesta pesquisa, objetivou-se identificar locos de caracteres quantitativos (QTL) associados com resistência à cercosporiose e com produção de grãos em germoplasma de milho tropical. Foram utilizadas duas linhagens contrastantes em níveis de reação à doença (genótipos pertencentes à GENESEEDS - Ltda), seu híbrido F1 e a população segregante F2. Essas plantas foram fenotipadas quanto à resistência a doença e quanto a produção de grãos e genotipadas com 94 marcadores de microssatélites. A associação dos marcadores ao QTL foi realizada por meio de análises de marcas individuais, utilizando as metodologias de regressão linear e análise da máxima verossimilhança. Observou-se que o tipo de efeito predominante no controle genético da resist��ncia a cercosporiose foi o aditivo e para o controle genético da produção de grãos foi de dominância. Os marcadores microssatélites mais promissores para serem utilizados em estudos de seleção assistida para resistência a cercosporiose são umc2082 na posição 4.03 e umc1117 na posição 4.04 e para produção de grãos, umc1042 e umc1058 nas posições 2.07 e 4.11.

The main goal of this study was to assess the nature and magnitude of gene effects for resistance to Cercospora leaf spot. A randomized block design with three replications was used. The data were obtained at the plant level by assessing the disease severity. The data were analyzed per experiment, using the average data per plot. A dominant-additive genetic model without epistasis was considered, with estimation of the components of means and variance. The genetic control of resistance to gray leaf spot is polygenic with predominance of the additive effects. Dominance was observed in a few small-effect loci and high heritability values.

The seeds of sweet corn have high levels of soluble sugars and low starch content. These characteristicscan cause rapid loss of seeds viability. The aim of this study was to evaluate the physiological quality of seeds storedunder different conditions. The seeds used were a round shape super sweet maize of the cultivar SWB585. Seeds weresoaked in distilled water with gibberellic acid at concentrations of 0, 10 and 20 mg.l-1. After drying they were packedin vacuum plastic and paper packaging, and then stored in two environments (cold and room temperature), during fivestorage periods (0, 60, 120, 180 and 240 days). The following tests were carried out: germination, cold test, acceleratedaging and emergence speed rate. Acompletely randomizedexperimental design was used, in a factorial scheme 2 x 2 x3 x 5 (two types of packaging, two environments, three doses of GA3 and five storage times), with four replications. Itwas found that the packaging did not affect the physiological quality. Gibberellic acid loses effect on seed performancealong the storage time. The vigor of sweet maize seeds decreases linearly over time of storage.

O uso sucessivo de híbridos de milho com resistência variada aos fungos causadores de podridão de grãos tem causado aumento na importância dessas doenças a cada safra. Conduziu-se este trabalho com o objetivo de avaliar pelo teste de sanidade (blotter test) a severidade do fungo Fusarium verticilioides e a incidência dos fungos Stenocarpella maydis e Stenocarpella macrospora em grãos de milho, oriundos de híbridos comerciais, com e sem a inoculação artificial a campo, em dois sistemas de cultivo, convencional e sistema de semeadura direta e em dois anos agrícolas. O experimento foi conduzido a campo, em blocos casualizados, com três repetições. Em laboratório, foram avaliadas, pelo método de "blotter test", a severidade do fungo F. verticilioides e a incidência dos fungos S. maydis e S. macrospora causadores de podridões de espiga. A avaliação pelo teste de sanidade (blotter test) evidenciou a diferença entre os híbridos quanto a reação aos fungos F.verticilioides, S. maydis e S. macrospora. Houve influência do híbrido, da safra agrícola e do sistema de cultivo sobre a infecção dos fungos causadores de podridões de espigas, sendo que o sistema plantio direto favorece o aumento dos fungos responsáveis pelos grãos ardidos em milho. A utilização da inoculação artificial, em campo, visando a selecionar genótipos resistentes aos fungos causadores do "complexo de grãos ardidos" é eficiente.The continued use of corn hybrids with varied resistance to grain rot-causing fungal agents increases the importance of these diseases every year. The objective of this work was to evaluate, by a sanitary test (blotter test), the severity of the fungus Fusarium verticilioides and the incidence of Stenocarpella maydis and Stenocarpella macrospora in corn grain from commercial hybrids, with and without in-field artificial inoculation, under two cultivation systems (conventional and direct sowing), over two crop seasons. The experiment was carried out under field conditions, using an experimental randomized blocks design, with three replications. In the laboratory, the severity of F. verticilioides and the incidence of S. maydis and S. macrospora ,the causative agents of ear rot in corn, were evaluated by the "blotter test" method. The blotter test evaluation allowed us to detect differences between the hybrids in their reactions to the fungi F. verticilioides, S. maydis and S. macrospora. The crop season and cultivation system used had the most influence on fungal infection in the hybrids. The direct sowing system showed an increase in the fungal infection responsible for causing grain rot. The use of artificial inoculation, in-field, to select genotypes resistant to the fungal agents causing the "grain rot complex" is efficient.

The objective of this study was to evaluate the effects of stalk/leaf ratio and the stage of maturity on the digestibility of the corn plant. Hybrids AG1051, AG4051, AG5011, DOW2B710, DOW2C577, DOW2A525, NB7315 and P30F90 were used, harvested at the one-half milk line (½ ML), three-quarters milk line (¾ ML) and black layer (BL) stages. A randomized block design was used in an 8 (hybrids) × 3 (stages of maturity) factorial design, with three replications. The means generated were used for grouping into high and low stalk/leaf ratio and a new analysis of variance was generated in a 2 × 3 (two groups and three stages of maturity) factorial design. The whole plant and its stalk, leaf, husk, cob and grain components were incubated in situ in the rumen of three cows for determination of degradability of dry matter and degradable neutral detergent fiber. Stalk/leaf ratio did not influence neutral detergent fiber content or the degradability of dry matter and neutral detergent fiber of any of the components, except for the cob, in which the high ratio group had greater degradable neutral detergent fiber contents. There was a reduction in the degradability of all the parts, except for the stalk and cob, and an increase in the neutral detergent fiber contents of the vegetative parts, except for the stalk. Unlike the vegetative components, the neutral detergent fiber contents of the whole plant decreased throughout the stages evaluated. For degradable neutral detergent fiber, there was a reduction in the whole plant and in its components. The advance of maturity reduces the quality of the vegetative components; however, this loss in the entire plant is moderated by grain filling. Forage quality depends more on the quality of the components than on their proportions in the dry matter.

Nitrogen (N) is the nutrient that most interferes with maize productivity. The development of cultivarsefficient in N use is an effective strategy to reduce production costs and minimize the dependence on agriculturalinputs. The aim of this work was to evaluate maize cultivars as to their efficiency in absorbing and using N undercontrasting levels of this nutrient. The experiment was conducted in the experimental area of the Federal Universityof Lavras (UFLA), in Lavras, MG, Brazil, in the agricultural year 2006/07. The experimental design was randomizedblocks, with 20 treatments and three replicates, in a 10 x 2 factorial arrangement consisting of 10 cultivars and twoN doses. The characteristics evaluated were grain yield, dry matter weight and N content in grains and shoot. Thenutritional efficiency indices of the cultivars were also evaluated. The maize cultivars presented different behaviorconcerning most of the adopted nutritional efficiency indices. Contrasting nitrogen levels allowed the occurrence ofdifferences among the studied characteristics, which were necessary for the selection of the most efficient cultivars.The hybrids GNZ 2004 and P 30F53 stood out for presenting the best performances for the efficiency parameters used.

The objective of this work was to evaluate the correlation and the influence of qualitative characteristicsof the components of the maize plant in the quality of the forage. Eight maize cultivars were harvested at three stagesof grain maturity, half milk line (½ ML), three-quarters milk line (¾ ML) and black line (BL). The experimentaldesign was a randomized block, with three replicates, in an eight (hybrids) x tree (cutting date) x two (sowing date)factorial scheme,. The quality of the vegetative components influenced significantly the quality of the forage. Thedegradability (DEG) of the vegetative components presented greater correlation with degradability of the whole plantdry matter than degradability and density of grain. Advancing plant maturity affected degradability (DEG), fiber inneutral detergent (FDN) and fiber in neutral detergent degradability (FDND) of the whole plant and their components,except for fiber in detergent neutral degradability of stalk. The group of high degradability of dry matter of the wholeplant presented better values of degradability, fiber in detergent neutral and fiber in detergent neutral degradability forall the components except straw FDN, FDND leaf and FDND straw with no differences among the appraised groups.

Em razão da sua resistência à seca, o sorgo forrageiro na forma de silagem é considerado um dos cultivos mais comuns para a alimentação de ruminantes em propriedades da região Norte de Minas Gerais. Para um melhor manejo cultural do sorgo, objetivou-se, neste trabalho, avaliar três densidades de plantas e três espaçamentos entre fileiras na condição climática do semiárido. Para isso, foram conduzidos experimentos, em dois anos agrícolas. Em cada ano foram instalados experimentos em áreas contíguas, utilizando se, respectivamente, os espaçamentos entre linhas de 50 cm, 70 cm e 90 cm. Cada experimento foi conduzido sob o delineamento experimental de blocos casualizados em esquema fatorial 4 x 3, com três repetições, sendo quatro cultivares e três densidades de semeadura. A viabilidade da redução do espaçamento entre fileiras no sorgo forrageiro é dependente da cultivar em função da condição climática. O aumento da densidade de semeadura proporciona redução na produtividade de matéria seca.Due to its resistance to drought, forage sorghum used as silage, is one of the most common feeds for ruminants on farms in the northern part of the State of Minas Gerais. The present research evaluated three planting densities and three forms of row spacing to determine their efficiency in the production of mass under the semiarid climatic conditions. Two experiments were conducted in two agricultural years. In each year, the experiments were conducted in contiguous areas using row spacing of 50, 70 and 90 cm and three different plant densities. Each experiment used a random blocks design in a 4 x 3 factorial scheme with three replicates, four cultivars and three sowing densities. The viability of reducing the space between rows was found to be dependent on the characteristics of each cultivar as well as the climatic conditions. Increasing sowing density resulted in a proportional reduction in the production of dry matter.

The objective of this experiment was to evaluate the production of structural components and theirproportion in a whole maize plant dry matter harvested at different maturity stages. The commercial hybrids AG 1051,AG 4051, AG 5011, DOW 2B710, DOW 2C577, DOW 2A525, NB 7315 and P 30F90 were used. Harvests weredone at three maturity stages: half of milk line (½ ML), three quarters of milk line (¾ ML) and black layer (BL). Theexperiment was sown in Lavras, MG, Brazil at 2007/2008 crop season. The experimental design was a randomizedblock with three replicates, in an 8 x 3 factorial scheme. The participation of vegetative portion decreased with thedelay in harvest, except to cob. The grain component increased its yield and proportion in dry matter, being themain component that contributed to increase of the whole plant dry matter yield. The higher yield and proportion indecreasing order were grains, stalks, leaves, straws, and cobs. The leaves presented the largest contribution to the grainfilling. The change in the relations among fractions over maturity stages can be one of the causes of forage quality loss.

O Brasil é um dos maiores produtores de milho do mundo e possui grande potencial para a produção de milho verde. Além de agregar valor ao produto, a comercialização de milho verde cresceu muito nos últimos anos. Há escassez de informações sobre a avaliação e a obtenção de cultivares destinadas à produção de milho-verde e também sobre estudos genéticos das características envolvidas nessa produção. Objetivou-se, neste trabalho, estimar parâmetros genéticos e fenotípicos, a correlação genética, classificar e identificar híbridos de milho verde promissores ao mercado consumidor e avaliar a eficiência dos pesos econômicos atribuídos. Os resultados determinaram que a seleção terá sucesso, para as diferentes características de milho-verde, pois, a herdabilidade foi de alta magnitude para as características avaliadas. A avaliação da produtividade de espigas empalhadas (PEE) é suficiente para definir quais os híbridos apresentam o melhor desempenho para a produtividade de espigas comerciais (PEC), diâmetro (DIAM) e comprimento de espigas (COMP). Isso indica que as características PEC, DIAM e COMP podem ser descartadas da avaliação em programas de melhoramento de milho-verde. Os híbridos HS48, HS27, HS24, HS25, HS12 e HS45 acumularam um maior número de características desejadas em um único genótipo, com base no índice de seleção baseado na soma de postos, sendo os mais promissores para a produção de milho-verde. Os pesos econômicos utilizados foram capazes de distinguir e identificar os híbridos mais promissores para a produção de milho- verde e podem ser utilizados como critério de seleção em programas de melhoramento de milho-verde.Brazil is one of the largest producers of corn of the world and it possesses great potential for vegetable corn production. Besides adding value to the product, the commercialization of vegetable corn increased in the last years. There is shortage of information about the evaluation and the acquisition of genotypes destined to the production of vegetable corn and also on genetic studies of the traits involved in this production. The objective of this work was to estimate the genetic and phenotypic parameters, and the genetic correlation, and to classify and identify hybrids of promising vegetable corn to the consumer market and to evaluate the efficiency of the attributed economical weights. The results determined that the selection will succeed, for the different traits of vegetable corn, because the heritability was of high magnitude to the appraised traits. Evaluation of husked ears yield (PEE) was enough to define which hybrid presents better commercial ear productivity, diameter and corn ear length. This indicates that those traits could be discarded in the selection process of genotypes of breeding programs for vegetable corn production. The hybrids HS48, HS27, HS24, HS25 and HS12 accumulated the largest number of desirable traits in a single genotype based on the sum of rank index. The used economical weights were efficient to distinguish and identify the most promising hybrid for vegetable corn production and they can be used as a selection criterion in programs of breeding of vegetable corn.

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.

A composição química das sementes pode ser influenciada por fatores genéticos, ambientais e pela disponibilidade de nutrientes no solo durante a produção e, como consequência, terem o seu vigor afetado. O potássio pode influenciar a atividade de várias enzimas presentes nas plantas, necessárias em várias reações envolvidas na utilização de energia, síntese de amido, metabolismo do nitrogênio e respiração. Avaliou-se o efeito da adubação potássica e da calagem na composição química, qualidade fisiológica e na atividade de enzimas de sementes de soja. A pesquisa foi desenvolvida nos laboratórios de análises e biotecnologia de sementes do Departamento de Agricultura e no Laboratório de Produção Vegetal do Departamento de Ciências dos Alimentos da Universidade Federal de Lavras (UFLA). Em sementes de soja do cultivar Msoy 8001, produzidas sob 2 níveis de saturação por base (48% e 85%) e quatro doses de K2O por hectare (0, 50, 100 e 200 kg), foram avaliados teores de óleo e proteína, germinação, envelhecimento acelerado e atividade das enzimas envolvidas nos processos de germinação e deterioração de sementes. A adubação potássica não afeta a germinação e o vigor das sementes, enquanto a elevação da saturação por base, proporciona maior vigor de sementes de soja. Há aumento no teor de óleo e redução no teor de proteína em sementes de soja à medida que a dose de K2O é aumentada. Ocorre aumento de teor de proteínas em sementes de soja, produzidas sob maiores níveis de saturação por base. A atividade das enzimas piruvato quinase, esterase e álcool desidrogenase em sementes de soja é afetada pela concentração de potássio e saturação por base no solo.The chemical composition of seeds can be influenced by genetical and environmental factors and by the availability of nutrients in the soil during production, which consequently affect their vigor. Potassium can influence the activity of several enzymes present in plants. These enzymes are necessary in a number of reactions involved in the utilization of energy, starch synthesis, nitrogen metabolism and respiration. The effects of potassium fertilization and liming on the chemical composition, physiological quality and enzymes activities of soybean seeds were evaluated. The research was developed in the Seed Analysis Laboratory of the Agriculture Department and in the Plant Production Laboratory in the Food Science Department of the Federal University of Lavras, Lavras (UFLA). In soybean seeds of cultivar Msoy 8001 produced under two levels of base saturation (48% and 85%) and four doses. ha-1 of K2O, 0, 50, 100 and 200, oil and protein contents, seed germination, aging test and the activity of some enzymes involved in the seed germination and deterioration processes were evaluated. Seed germination and vigor are not influenced by fertilization with potassium. However, base saturation increases the vigor of soybean seeds. Highert doses of potassium increase oil content and reduce protein in soybean seeds. High base saturation level increases the protein content. The activities of the enzymes piruvate kinase, esterase and alcohol dehydrogenase are altered by the doses of potassium and levels of soil base saturation.

A cobertura vegetal é a defesa natural do solo contra a erosão hídrica. Nos modelos de estimativas de perdas de solo, o efeito da cobertura vegetal na interceptação da energia cinética da chuva é a variável chave na modelagem do processo erosivo. Assim sendo, objetivou-se avaliar a eficiência da cobertura vegetal, proporcionada pela cultura do milho, e suas relações com os atributos fitotécnicos desta cultura para alguns híbridos. O estudo foi realizado no campo demonstrativo de híbridos de milho da Universidade Federal de Lavras, localizada no município de Lavras, MG. Para determinação da cobertura vegetal utilizou-se um aparato que consiste em uma estrutura horizontal, contendo orifícios para visualização dos pontos com cobertura e sem cobertura vegetal, sendo as leituras feitas de forma aleatória e transversalmente às linhas da cultura. Os atributos fitotécnicos avaliados foram altura da planta, estande, matéria seca e produção de grãos. Diante dos resultados pode-se concluir que o maior índice de cobertura vegetal foi observado para os híbridos de milho P 30F33, P 30F90, P 3021, STRIKE, FORT, VALENT, UFLA 2001, UFLA 2004, CO 32, D 8480, D 8420 DKB 333B, DKB 440, evidenciando boa qualidade como planta protetora do solo. No período de maior ocorrência de chuvas, na região sul de Minas Gerais, a cultura do milho pode minimizar o efeito do processo erosivo. A produção de matéria seca relacionou-se bem com o índice de cobertura vegetal, podendo ser um indicativo quanto à proteção do solo.The plant cover is a natural protection of soil against water erosion. In estimative models of soil loss, the effect of plant cover in the interception of rainfall kinetic energy is the key variable in the modeling of the erosive process. Thus, the aim of this work is to evaluate the efficiency of the plant cover provided by the corn crop and their relations with the phytotechnical attributes of this crop for its respective hybrids. This study was conducted in the corn hybrids demonstrative field at the Federal University of Lavras, Minas Gerais State, Brazil. In order to evaluate the plant cover a display was used that included a horizontal structure, containing holes for viewing the points with and without plant cover, the being readings performed at random and transversally to the crop lines. The phytotechnical attributes evaluated were plant height, stand, dry matter and grain production. It can be concluded that the higher plant cover index was observed for corn hybrids P 30F33, P 30F90, P 3021, STRIKE, FORT, VALENT, UFLA 2001, UFLA 2004, CO 32, D 8480, D 8420 DKB 333B, and DKB 440, proving good quality as a protective soil plant. In the period of larger occurrence of rainfall in the south of Minas Gerais state, the corn crop can minimize the effect of the erosive process. The production of dry matter was well correlated with the plant cover index, and can be used as evidence of soil protection.

In Brazil, technicians, in most cases, ignore the aspects related to the spatial variability of the soil acidity attributes when liming requirement is calculated. The objective of this study was to validate the liming practice, evaluating the presence of spatial variability of the soil acidity attributes and the existence of areas with differentiated liming requirement, which were calculated by different methods. The experiment was carried out in an area cultivated with corn under conventional management and irrigation. The soil (0-0.2 m) was sampled in a conventional way (composite soil sample) and in a systematic scheme, by use of a grid sampling. In sequence to the soil fertility attributes analysis, it was calculated the liming requirement, according to the methods of SMP pH, aluminum neutralization and elevation of soil Ca and Mg levels, and increase of the soil base saturation. After the descriptive analysis of the data set was accomplished, the semivariograms were calculated and the maps were obtained through the kriging technique. Absence of spatial dependence, as well as the non necessity of limestone application, was observed for the Al neutralization calculation method. Spatial dependence was only verified for the soil acidity attributes and to the liming requirement calculated by the base saturation and SMP pH methods; for these two methods, the semivariogram ranges obtained varied from 35.7 to 200.5 m. The results have highlighted the existence of differentiated liming requirement zones when the variability of the soil acidity attributes was considered in the calculation of the dose and type of limestone to be used for corn soil acidity correction.No Brasil, a prática de calagem desconsidera, na maioria das vezes, os aspectos relacionados à variabilidade espacial dos atributos de acidez do solo. Objetivou-se, neste estudo, validar a prática da calagem, avaliando a presença de variabilidade espacial de atributos de acidez do solo e a existência de áreas com necessidades diferenciadas de corretivo, por meio de diferentes métodos de cálculo da necessidade de calagem. O experimento foi realizado em lavoura de milho sob manejo convencional. O solo foi amostrado de forma convencional (amostra composta) e sistemática (mediante uso de grade amostral), na profundidade de 0-0,2 m. Posteriormente à análise de fertilidade de rotina, determinaram-se as necessidades de calagem segundo os métodos do tampão SMP, da neutralização de alumínio e elevação do Ca e Mg, e da saturação por bases. Após análise descritiva, foram obtidos os semivariogramas e os mapas por krigagem. Ausência de dependência espacial, assim como da necessidade de aplicação do corretivo calcário foram observadas para o método da neutralização de Al. A dependência espacial foi encontrada para os atributos de acidez do solo e para as necessidades de calagem calculadas pelos métodos de saturação por bases e pH SMP, com alcances variando entre 35,7 e 200,5 m. Esses últimos mostraram também, uma coincidência regionalizada entre as maiores demandas de calcário. Os resultados permitiram evidenciar a existência de zonas de aplicação de calcário diferenciadas, quando consideradas a variabilidade dos atributos de acidez do solo no cálculo espacializado da dose e o tipo de corretivo calcário a ser utilizado.

This work aimed to evaluate dry matter (DM) and nutrient accumulation in the aerial parts of corn plants as a function of the phenological stages of plant development, using one hybrid with high grain yield potential (P 30F33) and another with high DM production potential (GNZ 2004). The randomized block design was used, in a split plot scheme with four replications, with the two hybrids as plots and eleven phenological stages of the culture as sub-plots. Maize cultivars accumulate dry matter, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, zinc and copper until near physiological plant maturity when the maximum accumulation is reached. Nutrients accumulation in the aerial parts occurred in the decreasing order: N > K > P > Ca > Mg > S > Zn > Mn > Cu > B. The nutrient absorption curves for GNZ 2004 and P 30F33 hybrids showed patterns similar to those observed in other works. The total amounts of nutrients required to produce one ton of corn grains were: 22.3 and 27.7 kg of N; 5.3 and 5.8 kg of P; 21.3 and 23.2 kg of K; 3.6 and 3.9 kg of Ca; 2.4 and 3.5 kg of Mg; 1.3 and 1.9 kg of S, respectively for the hybrids P 30F33 and GNZ 2004. The maximum DM accumulation in leaves and straws was obtained at phenological stage 6, and in stems, corn cobs and grains at stages 9 and 10 of plant development.

The study of micronutrients accumulation as a function of plant development stage is of fundamental importance to subsidize strategies for fertilizer application and minimum amount to maintain soil fertility. This study evaluated micronutrient accumulation in two maize cultivars at different development stages. The experimental design was randomized blocks with four replications in split-plots, with two maize hybrids as the plots and sampling time according to development stages as sub-plots. Maize accumulated minimum amounts of B, Cu, Mn, and Zn in the initial stages of development, and the maximum accumulated values were observed after 100 days seedling emergency. The evaluated hybrids accumulated maximum of Zn and Cu close to physiological maturity. Maize plants accumulate nutrients in the above ground parts as follows: Zn > Mn > Cu > B. The total amount of nutrients required to produce one ton of corn is: 0.0009 kg B; 0.019 to 0.02 kg Cu; 0.042 to 0.046 kg Mn; 0.100 to 0.194 kg Zn.Estudar o acúmulo de micronutrientes em função dos estádios fenológicos da cultura é de fundamental importância para subsidiar estratégias de definição das quantidades e das épocas de realização de adubações na cultura, e das quantidades mínimas que devem ser restituídas ao solo para fins de manutenção da fertilidade. Neste trabalho, objetivou-se avaliar o acúmulo de micronutrientes em função dos estádios fenológicos da cultura, considerando dois híbridos de milho. O delineamento utilizado foi o DBC com quatro repetições, em esquema de parcelas subdivididas, sendo os dois híbridos de milho dispostos nas parcelas e, nas sub-parcelas, as épocas de coleta das plantas, considerando os estádios fenológicos da cultura do milho. Híbridos de milho acumulam quantidades mínimas de B, Cu, Mn e Zn nos estádios iniciais de desenvolvimento da cultura, sendo os valores máximos acumulados obtidos a partir de 100 dias após a emergência. Os híbridos de milho avaliados acumulam zinco e cobre até próximo à maturidade fisiológica, quando são obtidos os acúmulos máximos. Híbridos de milho acumulam micronutrientes em sua parte aérea na seguinte ordem decrescente: Zn>Mn>Cu>B. As quantidades de micronutrientes necessárias para produzir uma tonelada de grãos de milho são: 0,0009 kg de B; 0,019 a 0,020 kg de Cu; 0,042 a 0,046 kg de Mn; 0,100 a 0,194 kg de Zn.

Objetivou-se, neste trabalho, avaliar o desempenho de cinco cultivares de milho submetidas a três densidades de semeadura e duas doses de fertilizantes em Lavras, MG. Foram conduzidos quatro experimentos, sendo dois em 2004 e dois em 2005. Em cada experimento as cinco cultivares (GNZ2005, AG9010, P3041, AG7000 e DKB350) foram avaliadas em três densidades de semeadura (45.000, 55.000 e 65.000 plantas ha-1) e em duas doses de fertilizantes ( alta dose - 400 kg ha-1 de 08-28-16 + 0,5% Zn, e 90 kg ha-1 de N em cobertura e baixa dose - 200 kg ha-1 de 08-28-16 + 0,5% Zn, e 45 kg ha-1 de N em cobertura). Utilizou-se o delineamento blocos casualizados em esquema fatorial, com três repetições. A produtividade de grãos das cultivares foi influenciada apenas pelo ano de avaliação e pela interação anos versus cultivares. As doses de fertilizantes e as densidades de semeadura não influenciaram a produtividade de grãos das cultivares. Há cultivares mais adaptadas às condições de cultivo de milho safrinha na região. No primeiro ano de avaliação, as cultivares DKB 350 e AG 9010 e AG 7000 foram as que apresentaram o melhor desempenho enquanto que no ano de 2005 foram a DKB 350, e GNZ 2005. A adoção da maior dose de fertilizantes não proporciona incrementos significativos na produtividade de grãos de milho, porém provoca redução na porcentagem de plantasacamadas e quebradas. A densidade de 55.000 plantas ha-1 proporciona a maior produtividade de grãos.This work had the aim of evaluating responses of five corn cultivars to three sowing densities, fertilized with two fertilizer doses, in Lavras, MG, Brazil. Four experiments were carried out, being two in 2004 and two in 2005. Five cultivars (GNZ2005, AG9010, P3041, AG7000, and DKB350) were grown at three sowing densities (45,000; 55,000, and 65,000 plants ha-1) and in a fertilizer dose (high dose - 400 kg ha-1 of 08-28-16 + 0.5% Zn, and 90 kg ha-1 N in top dressing or in lower doses - 200 kg ha-1 of 08-28-16 + 0.5% Zn, and 45 kg ha-1 N in top dressing) in each experiment. The experimental design was a randomized block in a factorial scheme with three replications. Higher grain yield was promoted by 55,000 plants ha-1 when compared to the other densities; high rates of fertilizers did not promote increase in corn grain yield; the DKB 350, AG 9010, and AG 7000 cultivars showed better performance when compared to the other cultivars tested. Performances of all cultivars were similar regarding the rates of fertilizers and densities, with differences among growing seasons.

A utilização dos computadores na agricultura tem trazido inúmeros benefícios ao empresário rural. Entre tais benefícios, a utilização de programas de computador para simular o crescimento e desenvolvimento de plantas; bem como o seu uso na otimização de práticas culturais, tem se mostrado como uma opção. Objetivou-se, neste trabalho, avaliar o programa CERES-Maize na simulação do florescimento e produção de milho (Zea mays L.), em diferentes cenários de investimento. Os resultados das simulações com o programa CERES-Maize mostraram que as diferenças entre as produções simuladas, comparadas com os dados obtidos em campo, estão entre os limites de 5% a 8% de erro, aceitáveis pelo programa. A mesma tendência foi verificada entre os valores observados e simulados para os dias de florescimento, em todos os cenarios. O programa CERES-Maize mostrou-se bastante robusto e eficiente nas simulações efetuadas. O uso desse programa pode ser visto como uma ferramenta adicional ao produtor no processo decisório, durante o planejamento da implantação da cultura.The use of computers in agriculture has brought several benefits to the farmers. Among these benefits, the use of crop models to simulate plant growth and development, as well as a tool for optimization process and decision support aid, has been an option. The aim of this study was to evaluate the efficiency of Ceres-Maize model to simulate maize flowering date and yield at different investment scenarios. Simulation results showed that the difference between simulated and observed yield data were in the 5% and 8% error range, acceptable for the program. The same tendency was observed when comparing flowering dates in all scenarios. The model was very efficient and suitable for all of the simulations performed. Without any doubt CERES-Maize may be used as a tool, by farmers, in the crop planning process.

Com o objetivo de avaliar o desempenho agronômico de nove cultivares de milho, sendo cinco destinadas ao cultivo com baixo investimento e quatro cultivares destinadas ao cultivo sob condições de alto investimento, foram conduzidos dois experimentos no ano agrícola 2004/2005, em Lavras, MG. Em um dos experimentos, utilizou-se a densidade de semeadura de 55.000 plantas ha-1 e, no outro, 65.000 plantas ha-1. Em cada experimento, as nove cultivares de milho foram avaliadas em três níveis de adubação: (1) 300 kg ha-1 de 8-28-16 na semeadura, mais 200 kg ha-1 de 30-00-20, em cobertura; (2) 400 kg ha-1 de 8-28-16 na semeadura, mais 300 kg ha-1 de 30-00-20, em cobertura e (3) 500 kg ha-1 de 8-28-16 na semeadura, mais 300 kg ha-1 de 30-00-20 e 150 kg ha-1 de uréia, em cobertura. Os resultados permitiram concluir que a adubação de 500 kg ha-1 de 8-28-16 na semeadura, mais 300 kg ha-1 de 30-00-20 na primeira cobertura e 150 kg ha-1 de uréia na segunda cobertura proporciona aumento significativo na produtividade de grãos e na altura das plantas. O aumento da densidade de semeadura de 55.000 plantas ha-1 para 65.000 plantas ha-1 não influenciou a produtividade de grãos, mas, interferiu na altura de plantas e de espigas e na prolificidade. As cultivares destinadas ao alto investimento apresentam maior prolificidade, maior altura de planta e maior produtividade de grãos do que as cultivares destinadas ao baixo investimento.With the aim of evaluating the agronomic traits in nine maize cultivars, five being considered for cultivation of low investment and four maize crops considered for high investment, two trials were carried out in the agricultural year 2004/2005, in Lavras, MG. One of the trials was carried out with plant density of 55.000 plants ha-1 and the other, 65.000 plants ha-1. In each trial the nine maize crops were carried out in three fertilizing levels: (1) 300 kg ha-1 of an 8-28-16 formula at the sowing date, with an additional 200 kg ha-1 of a 30-00-20 formula, for covering; (2) 400 kg ha-1 of 8-28-16 at the sowing date, with an additional of 300 kg of 30-00-20, for covering; (3) 500 kg ha-1 of 8-28-16 at the sowing date, with an additional of 300 kg ha-1 of 30-00-20 and 150 kg ha-1 of N, for covering. The results allowed concluding that fertilizing with 500 kg ha-1 of 8-28-16 at the sowing date, with an additional 300 kg ha-1 of 30-00-20 and 150 kg ha-1 of N, for covering, the maize crops showed expressive increase in the productivity of grains and plant height. The increase of plant density from 55.000 plants ha-1 to 65.000 plants ha-1 did not influence the productivity of the grains, but interfered in the plant height, ear length, and prolificacy. The maize crops of high input showed higher prolificacy, higher plant height and higher productivity of grains in relationship to the crops of low investment.

The objective of this study was to evaluate stability and adaptability of the grain yield of commercial intervarietalmaize hybrids by the GGE (Genotype and Genotype by Environment Interaction) biplot and AMMI (Additive Main Effects andMultiplicative Interaction) analyses. Two intervarietal hybrids (BIO 2 and BIO4) were evaluated together with single, doubleand three-way cross hybrids. The performance of the intervarietal hybrid BIO 4 was superior to all double and three-waycross hybrids and outmatched the single-cross hybrids by 43%. In terms of stability, BIO 2 was more stable than BIO4, whichis desirable, but biological stability, which is not necessarily desirable, was also observed, since the yield was below theenvironmental mean. The graphical GGE biplot analysis was superior to the AMMI1 since a greater portion of the sum ofsquares of GE and G+GE was captured and the predictive accuracy was higher. On the other hand, the AMMI2 graphoutperformed the GGE biplot in predictive accuracy and explanation of G + GE and GE, although the difference in accuracywas smaller than between GGE2 and AMMI1.

Conduziu-se este trabalho com objetivo de avaliar o desempenho de 32 híbridos experimentais e 4 híbridos comerciais para produção de milho verde em Lavras, MG. O delineamento utilizado foi de blocos ao acaso com duas repetições. Foram avaliadas sete características de interesse agronômico e comercial para a produção de milho verde. Os dados obtidos foram submetidos à análise de variância, decompondo o efeito dos híbridos em híbridos comerciais, híbridos experimentais e híbridos comerciais versus híbridos experimentais. Foram feitos ainda estudos de correlação entre as diferentes características agronômicas dos híbridos. Entre os híbridos avaliados há híbridos experimentais promissores com desempenho superior a híbridos comerciais amplamente utilizados no Brasil. Considerando as características avaliadas, os híbridos AG 1051, AG 4051, GNS 03, GNS 21, GNS 23 e GNS 35 foram os mais promissores. É possível reduzir o número de características avaliadas em experimentos com milho verde, uma vez que existem associações entre as principais características avaliadas para essa finalidade. A produtividade de espigas empalhadas e despalhadas e a cor dos grãos são características imprescindíveis nessa avaliação.The objective of this research was to evaluate the performance of thirty-two experimental hybrids and four commercial hybrids of green maize at Lavras, MG. The experimental design was a randomized blocks with two replications. Seven characteristics of agronomic and commercial interest for the production of green maize had been evaluated. For each experiment, the data obtained were submitted to the analysis of variance decomposing the effect of the hybrids in commercial hybrids versus experimental hybrids. There were still made studies of correlation among the different characteristics. Among all of evaluated hybrids, there are experimental promising hybrids with performance superior to the commercial hybrids widely utilized in Brazil. Taking into account all the characteristics evaluated, hybrids AG 1051, AG 4051, GNS 03, GNS 21, GNS 23 and GNS 35 were the most promising. It is possible to reduce the number of characteristics evaluated as green maize, since there are high associations among the main characteristics evaluated for this purpose. The yield of strawed ears along and the color of the grains are indispensable characteristics in that evaluation.

With the objective of evaluating the severity of Gray Leaf Spot and grain yield in commercial maize hybrids and determining the best time to evaluate the disease, two experiments were carried out in two sowing seasons (two planted on 11/11/2005, and other two planted on 12/23/2005) at Lavras Federal University - UFLA, Lavras, MG, Brazil. Twelve commercial maize hybrids were used, in a randomized block experimental design with three replications. Eight evaluations of disease severity based on visual symptoms were performed at seven-days intervals from the 60th day after maize emergence (DAE), ranging from 1 (highly resistant) to 9 (highly susceptible). The area under the disease progress curve (AUDPC) was estimated and grain yield per plot was also obtained and so the correlation between severity of the disease in each evaluation season and the estimates of the AUDPC were supported by the data. Considering the data of the AUDPC, it was observed that the most resistant hybrids to Cercospora zeae-maydis were P 30K75, P 30F87, AG 7000, and DKB 350, while the most susceptible were AG 9020, DKB 214, and P 30F44. The most susceptible hybrids to Gray Leaf Spot are not necessarily those with lowest grain yield. The disease severity evaluation between 88 and 109 DAE is efficient to discriminate the level of resistance of the hybrids and the results are similar to those obtained by the AUDPC.

Searching for alternatives for selection of maize hybrids involving simultaneously several traits is desirable in any breeding program. This work was carried out to estimate heterosis and the effects of parents using multivariate diallel analysis as well as other methodologies which help distinguishing superior hybrids on the basis of selection for several characters. For this purpose, 6 high digestible and 6 low digestible lines were used in a 6 x 6 partial diallel plus the parental lines. Seeds from 36 hybrids and parental lines were sown in the experimental area of UFLA in two sowing seasons (November 4, 2001 and December 11, 2001). For each season, a 6 x 6 triple lattice was set up for the hybrids and a randomized block design with three replications for the 12 lines. Dry matter yield, grain yield, in situ dry matter degradability, and percentage of neutral detergent fiber were evaluated. From these four traits, multivariate diallel analysis was performed as well as a non-parametric selection index, called the graphic method, was applied. Only the hybrids of the diallel were used for this index. It was observed that multivariate diallel analysis results were similar to those of univariate diallel analyses. The results also corroborate, by multivariate diallel analysis, the importance of heterosis as well as the effects of parents in evaluating several characters simultaneously for maize silage production. The hybrid GNS 041 x GNS 079 provided good estimates of specific combining ability for traits, as well as the best performance by the graphic selection method. This hybrid has the potential to be used commercially for silage production. The graphic method for choosing cultivars considering a number of traits simultaneously is a good option for complementing multivariate diallel analysis.