G. Ceccon

Interação genótipo x ambiente em genótipos de feijão-caupi semiprostrado via modelos mistos

The mixed model methodology (REML / BLUP) has been used to study the effects of genotype x environment interaction (G x E) in various crops, such as: rice, common bean, cane sugar, cashew and eucalyptus, but still was not applied in cowpea. The aim of this work was to select simultaneously semiprostrade cowpea genotypes grown in the state of Mato Grosso do Sul, via mixed models, bringing together high adaptability, stability and yield grain. It were conducted four growing amount of trials and use of genotypes of cowpea genotypes in 2005 and 2006 in Aquidauana, Chapadao do Sul and Dourados. The experimental design was a randomized complete blocks with four replications and 20 genotypes. The genetic parameters were estimated by REML/BLUP methodology and, the selection was based on the MHPRVG method (harmonic mean of the relative performance of genetic values) in three strategies: selection based on predicted breeding value, having considered the performance mean of genotypes in all environments (no interaction effect) or performance in each environment (with interaction effect); and simultaneous selection for grain yield, stability and adaptability. BRS Paraguacu, MNC99-542F-5 and MNC99-508G-1 genotypes can be grown in various environments, as they bring together high grain yield, adaptability and stability. The heritability of the average of genotypes found indicates moderate to high, a fact which indicates excellent possibilities for selection, allowing selective accuracy of 82%.

LEGUMES AND FORAGE SPECIES SOLE OR INTERCROPPED WITH CORN IN SOYBEAN-CORN SUCCESSION IN MIDWESTERN BRAZIL

The feasibility of no-tillage in the Cerrado (Savanna-like vegetation of Brazil) depends on the production of sufficient above-ground crop residue, which can be increased by corn-forage intercropping. This study evaluated how above-ground crop residue production and yields of soybean and late-season corn in a soybean-corn rotation were influenced by the following crops in the year before soybean: corn (Zea mays L.) intercropped with Brachiaria (Urochloa) brizantha cv. Marandu, B. decumbens cv. Basilisk, B. ruziziensis, cv. comum., Panicummaximum cv. Tanzânia, sunn hemp (Crotalaria juncea L.), pigeon pea [Cajanus cajan (L.) Millsp]; sole corn, forage sorghum [Sorghum bicolor (L.) Moench (cv. Santa Elisa)], and ruzi grass. In March 2005, corn and forage species were planted in alternate rows spaced 0.90 m apart, and sole forage species were planted in rows spaced 0.45 m apart. In October 2005, the forages were killed with glyphosate and soybean was planted. After the soybean harvest in March 2006, sole late-season corn was planted in the entire experimental area. Corn grain and stover yields were unaffected by intercropping. Above-ground crop residue was greater when corn was intercropped with Tanzania grass (10.7 Mg ha-1), Marandu (10.1 Mg ha-1), and Ruzi Grass (9.8 Mg ha-1) than when corn was not intercropped (4.0 Mg ha-1). The intercropped treatments increased the percentage of soil surface covered with crop residue. Soybean and corn grain yields were higher after sole ruzi grass and intercropped ruzi grass than after other crops. The intercropping corn with Brachiaria spp. and corn with Panicum spp. increases above-ground crop residue production and maintains nutrients in the soil without reducing late-season corn yield and the viability of no-till in the midwestern region of Brazil.

EFEITO DE INSETICIDAS NA SEMEADURA SOBRE PRAGAS INICIAIS E PRODUTIVIDADE DE MILHO SAFRINHA EM PLANTIO DIRETO (1)

EFFECT OF INSETICIDES AT SOWING ON SEEDLING PESTS AND YIELD OFF-SEASON MAIZE CROP UNDER NO-TILLAGE SYSTEM Due to an increasing pest diversity in maize crop during the off-season, two autumn-winter experiments were conducted in the Medium Paranapanema region, State of Sao Paulo, Brazil, designated as Fields A and B, both in Cândido Mota County. The aim of the experiments were to evaluate the effect of insecticides on the control of pests occurring in the initial plant development. Treatments were the recommended dosage of the insecticides thiamethoxam (Cruiser 700 WS), carbofuran (Furazin 310 TS), imidacloprid (Gaucho FS), imidacloprid (Gaucho FS) + carbofuran (Furazin 310 TS), fipronil (Regent 800Due to an increasing pest diversity in maize crop during the off-season, two autumn-winter experiments were conducted in the Medium Paranapanema region, State of Sao Paulo, Brazil, designated as Fields A and B, both in Cândido Mota County. The aim of the experiments were to evaluate the effect of insecticides on the control of pests occurring in the initial plant development. Treatments were the recommended dosage of the insecticides thiamethoxam (Cruiser 700 WS), carbofuran (Furazin 310 TS), imidacloprid (Gaucho FS), imidacloprid (Gaucho FS) + carbofuran (Furazin 310 TS), fipronil (Regent 800 WG), thiodicarb (Semevin 350 RPA); and the control (without insecticide). The soil insects (burrowing bugs and grubs) populations were evaluated at 14th and 28th days after plant emergency (DAE), in Field A, and at 7th and 21th DAE, in the Field B. Spodoptera frugiperda incidence and corn plant parameters were evaluated at 14th and 28th DAE. Fipronil and carbofuran performed best on the control of Scaptocoris castanea. Fipronil alone provided also the best control for grubs (Phyllophaga spp.). Carbofuran and thiodicarb reduced damages from fall armyworm. The chemical control of corn pests in the initial stage of the crop enhanced grain productivity only in the field A were the number of grubs in the soil was highest.

Estimativas de parâmetros genéticos e correlações entre caracteres fenológicos e morfoagronômicos em feijão-caupi

Mensurar a variabilidade genetica e conhecer as correlacoes entre caracteres de interesse para selecao numa populacao constitui uma das etapas iniciais em um programa de melhoramento genetico. Com o objetivo de avaliar o potencial para o melhoramento genetico de uma populacao composta por 19 genotipos de feijao-caupi de porte ereto e semiereto, entre variedades comerciais e linhagens avancadas, foram estimados parâmetros geneticos e fenotipicos e correlacoes entre caracteres fenologicos e morfoagronomicos da populacao. O experimento foi conduzido na area experimental da Universidade Estadual de Mato Grosso do Sul, em Aquidauana, no periodo da seca do ano agricola 2007/2008. Foram avaliados os caracteres: dias para o florescimento (DF), dias para a maturacao (DM), massa de 100 graos (MCG), comprimento de vagem (CV), massa de vagem (MV), numero de graos por vagem (NGV) e produtividade de graos secos (PROD). Verificou-se efeito significativo de genotipos para todas as caracteristicas indicando existencia de variabilidade. O maior valor da estimativa do coeficiente de variacao genetica foi obtido para PROD, que tambem apresentou o mais alto valor de coeficiente b, 2,05, indicando condicao favoravel para selecao desse carater. Dentre os demais caracteres apenas para DM o valor do coeficiente b foi superior a um. Foram observadas correlacoes geneticas positivas e significativas entre todos os caracteres e PROD, sendo as mais elevadas com DF, MV e NGV. Concluiu-se que a populacao apresentou potencial para o melhoramento genetico e que aumento da produtividade de graos pode ser obtido principalmente para genotipos mais tardios.

Rendimento de grãos de aveia branca (Avena sativa l.) em densidades de plantas e doses de nitrogênio

This work had the aim to evaluate white oat grain yield as influenced by different plant densities and nitrogen levels. The experiment was carried out in the Lageado experimental farm at UNESP in the county of Botucatu in Sao Paulo state, Brazil. White oat was sown directly over corn residues in a Rhodic kanhapludalf soil. The experimental design was a split plot with four randomized blocks. Plant densities were allocated in plots and nitrogen levels in subplots. The results showed significant interaction between plant densities and nitrogen levels. Grain yield was positively influenced by plant densities and nitrogen level. The final number of panicle was negatively influenced by plant densities and was positively influenced by nitrogen levels. The weight of one thousand grains was greater at higher plant densities and at moderate nitrogen levels. With reduction in the initial density of plants, the expected yield grain was obtained with increase in the level of nitrogen in cover. In the normal density of plants and recommended levels of N in covering, the obtained yield of grains was larger than the expected.

Acúmulo de matéria seca e de nutrientes em forrageiras consorciadas com milho safrinha em função da adubação nitrogenada

The objective of this work was to assess the accumulation of dry matter and nutrients in forage plants intercropped with off-season maize, as a function of nitrogen fertilization. The species Urochloa brizantha cv. Marandu, U. decumbens cv. Basilisk, U. ruziziensis cv. Comum, and Panicum maximum cv. Tanzânia, with seeding in mid-March, were evaluated in four municipalities of Sao Paulo, Brazil, intercropped with maize. A randomized complete block design was used, with four replicates, in split-plots. The intercropped systems were evaluated in the plots, and four nitrogen topdressing fertilization rates (0, 30, 60, and 90 kg ha -1 ) were evaluated in the split-plots. Forage dry matter and nutrient accumulation were determined in three stages: flowering, maize physiological maturity, and at forage desiccation, in October. Forage dry matter accumulation increases after the harvest of off-season maize. When forages are planted in the corn inter-rows, topdressing nitrogen fertilization does not influence forage dry matter and nutrient accumulation, and intercropping does not affect off-season maize grain yield.

Uso de herbicidas no consórcio de milho safrinha com Brachiaria ruziziensis

This study aimed to evaluate the behavior of intercropped Brachiaria ruziziensis and off-season corn after application of the herbicides atrazine (1.760 g a.i ha-1), mesotrione (60 g a.i ha-1), mesotrione + atrazine (1.760 and 60 g a.i. ha-1), and nicosulfuron (8 and 16 g a.i. ha -1 ) on the 14th and 24th days after Brachiaria emergence. Corn was sown mechanically in 0.90 m spaced rows under a no-till system with an intermediary line of B. ruziziensis in Dourados, Mato Grosso do Sul Brazil, on March 7, 2008. Atrazine did not cause visible signs of toxicity on the Brachiaria leaves, while mesotrione caused bleaching of the tips of the leaves, resuming rapid growth. Nicosulfuron caused leaf chlorosis with necrosis and reduced growth of Brachiaria, without full plant recovery during corn growth, leading to low yield forage mass. The old stems, grown during corn cultivation, accounted for higher Brachiaria mass yield and were little affected by atrazine and mesotrione, which can be used in the intercropping system. Off-season corn grain yield was not significantly altered by the treatments.

Adaptabilidade e estabilidade de genótipos de feijão caupi ereto via REML/BLUP e GGE Biplot

The objective of this study was to investigate the association between the GGE Biplot and REML/BLUP methods and select cowpea genotypes that meet simultaneously high grain yield, adaptability and stability in the Mato Grosso do Sul environments. The experiments were carried out from February to July 2010, 2011 and 2012 in the municipalities of Dourados, Aquidauana and Chapadao do Sul. The experiments in Chapadao do Sul were conducted only in the years of 2010 and 2011, totaling eight environments. After detecting significant genotypes × environments (GE) interaction, the adaptability and the phenotypic stability of cowpea genotypes were analyzed by GGE Biplot and REML/BLUP methods. These methods were concordant in the identification of the best cowpea genotypes for the State of Mato Grosso do Sul. The BRS- Tumucumaque and BRS-Guariba cultivars are the closest to the ideal in terms of high grain yield and phenotypic stability, being suitable for cultivation in the State.

Phytosociology in agricultural areas submitted to distinct wintercropping management

Studies related to weed dynamics are essential for agricultural sustainability in tropical soils, as their interference can cause significant yield losses, especially in crops with lower competitive ability. This study aimed to assess the composition of weed communities in the third cropping season in areas submitted to distinct wintercroppings for two consecutive years. Evaluations were made in terms of species composition, level of infestation, and severity of occurrence of each weed species in relation to the others within the same area. The wintercropping management systems were: (1) Brachiaria ruziziensis; (2) corn intercropped with B. ruziziensis; (3) corn and (4) cowpea. Plant communities under these wintercrop systems were evaluated in the third year in terms of relative frequency, relative dominance, relative abundance and importance index for each species. Areas were also compared in terms of species composition by the Sorensens similarity coefficient. Two years of distinct wintercrop managements were not enough to cause a significant shift in terms of weed composition and severity in a given area. There is also evidence that some weed species are more favored by specific crops, although the causes of this selective behavior are not fully explored in this article. The presence of B. ruziziensis, either alone or intercropped with corn, resulted in lower similarity coefficients when compared to areas where this species was not present. It is suggested that several mechanisms briefly discussed may be involved in the impact of the presence of B. ruziziensis on the weed community.

Desempenho agronômico de feijão‑caupi e milho semeados em faixas na safrinha

Universidade Estadual Paulista Faculdade de Ciencias Agronomicas Departamento de Producao e Melhoramento Vegetal