RESUMO -O presente estudo teve o objetivo de determinar genótipos superiores de girassol, bem como realizar estudos de correlação entre suas características. Avaliou-se seis híbridos de girassol em condições de safrinha no município de Palotina -PR. O estudo avaliou quinze variáveis: massa seca de folhas, massa seca de caule e pecíolos, massa seca total, área foliar, altura de planta, diâmetro de colmo, massa de grãos por capítulo, diâmetro de capítulo, percentagem de grãos normais, massa de mil grãos, número de grãos por capítulo, produtividade, teor de proteína bruta, teor de óleo e rendimento de óleo. Os dados direcionam os híbridos H360 e MG2 com boa produtividade e maior teor de óleo para a produção de óleo e os híbridos M734 e Aguará 3 para a alimentação animal, com boa produtividade e menor teor de óleo. As correlações entre produtividade e os componentes de produção foram de 0,62; 0,47; 0,60; 0,49 e 0,47 para massa de grãos por capítulo, diâmetro de capítulo, percentagem de grãos normais, massa de mil grãos e número de grãos por capítulo, respectivamente, concluindo que a seleção de materiais a partir desses componentes ocasionará a seleção de materiais promissores em produtividade. Palavras-chave:Hellianthus annuus L. Correlação. Genótipos. ABSTRACT -The objective of this work was to determine superior genotypes of the sunflower, as well as to study the correlation between its characteristics. Six sunflower hybrids were evaluated under late-summer conditions in Palotina in the state of Paraná. The study evaluated fifteen variables: leaf dry mass, stem and petiole dry mass, total dry mass, leaf area, plant height, stem diameter, grain weight per head, head diameter, percentage of normal grains, thousand grain weight, number of grains per head, productivity, crude protein content, oil content and oil yield. According to the data, the hybrids H360 and MG2, with good productivity and higher oil content, are indicated for oil production, and the hybrids M734 and Aguará 3, with good productivity and lower oil content, for animal feed. The correlation between productivity and yield components were 0.62, 0.47, 0.60, 0.49 and 0.47, for grain weight per head, head diameter, percentage of normal grains, thousand grain weight and number of grains per head respectively, leading to the conclusion that the selection of materials from among these components will result in the selection of promising materials for productivity.

O sistema plantio direto (SPD) é uma técnica eficiente no controle da erosão do solo porém alguns estudos indicam a ocorrência de compactação, principalmente na camada superficial. Estratégias que elevem o teor de matéria orgânica, como a rotação de culturas e a adubação orgânica, podem ser utilizadas para resolver este problema. O objetivo do trabalho foi avaliar o efeito de sistemas de manejo (rotação e sucessão de culturas) e adubações (mineral, orgânica e organomineral) sobre as propriedades físicas do solo e a produtividade do milho, de 2006 a 2008. As avaliações foram realizadas em fevereiro de 2007, após a colheita do milho de verão, e em setembro de 2008, após a colheita do milho safrinha. A rotação de culturas promoveu redução na densidade e resistência do solo à penetração e elevação na macroporosidade e porosidade total. O uso de fontes orgânicas de adubação não apresentou efeito sobre os atributos físicos do solo. Na safra de verão a produtividade do milho foi superior na sucessão de culturas e na adubação mineral; entretanto, na safrinha não houve diferença entre os sistemas de manejo nem entre as adubações.

Based on the hypothesis that alternative substrates should improve the yield of lettuce crops by producing better quality seedlings, the objective of this work was to evaluate the effect of different substrates on the production of seedlings of this species, and their growth in the field. The study was in two stages. The first consisted of the production of lettuce seedlings, and the second assessed their development in the field. Four alternative substrates were tested, obtained by mixing together a sieved vermicompost from which all clumps had been removed, sterilized sand, charred rice husks and basalt powder. The commercial substrate, Plantmax HA , was also tested. In the first phase, which was conducted in a completely randomised design with four replications, the height, root length, number of leaves, leaf area and dry weight of the seedlings were all evaluated 28 days after sowing. In the second phase, which was carried out in the field in a randomised block design with four replications, the plants were harvested 50 days after transplanting and the head diameter, fresh weight, number of leaves and leaf and stem dry weight were evaluated. The alternative substrates produced larger seedlings in less time than the commercial substrate, resulting in a reduction of 10 days in the total crop cycle. The reduction in the time between sowing and harvesting, together with those aspects relating to sustainability, are the main advantages of the use of alternative substrates, since in the field crop production did not differ between treatments.

A rúcula vem se destacando dentre as hortaliças pela sua composição nutricional e pelo sabor picante e odor agradável. No entanto, são escassos os estudos sobre a nutrição mineral e qualidade do produto, principalmente para a espécie 'Selvática'. Visando suprir esta deficiência, foi conduzido um experimento em casa de vegetação com o objetivo de avaliar o efeito da adubação nitrogenada sobre a produção e o acúmulo de nitrato nas folhas de rúcula 'Selvática'. O delineamento experimental utilizado foi de blocos ao acaso em esquema fatorial 2 x 5 com quatro repetições. Os tratamentos resultaram da combinação de duas fontes de nitrogênio (ureia e nitrato de amônio) e cinco doses (0, 40, 80, 120 e 160 mg dm -3 de N). A colheita foi realizada 39 dias após o transplante das mudas. A rúcula 'Selvática', quando cultivada em ambiente protegido, responde até a dose de 135 e 160 mg dm -3 de N, na forma de nitrato de amônio e ureia, respectivamente. O teor e o acúmulo de Norgânico + N-NH 4 + (NOA) e de nitrato (NO 3 -) nas folhas de rúcula aumentaram linearmente com as doses de nitrogênio. Contudo, ressalte-se que os teores de NO 3 -ficaram abaixo do limite máximo admissível para o cultivo de hortaliças folhosas em ambiente protegido. Palavras-chave:Cultivo protegido, Diplotaxis tenuifolia (L.) DC., hortaliça, nitrogênio. Arugula production and nitrate accumulation as function of nitrogen fertilization ABSTRACTThe arugula has been standing out among vegetables due to its nutritional composition, spicy flavor and pleasant scent. However, there are few studies on mineral nutrition and product quality, especially for 'Savage' species. Aiming to supply this deficiency, an experiment was carried out under greenhouse conditions, to evaluate the effect of nitrogen fertilization on the production and accumulation of nitrate in the leaves of 'Savage' arugula. The experimental design was made in randomized blocks, in a 2 x 5 factorial scheme with four replications. The treatments resulted from the combination of two nitrogen sources (urea and ammonium nitrate) and five doses (0, 40, 80, 120 and 160 mg dm -3 N). The crop was harvested 39 days after transplanting. The 'Savage' arugula, when grown in a protected environment, responds to doses of 135 and 160 mg dm -3 of N, as ammonium nitrate and urea, respectively. The content and accumulation of N-organic + N-NH 4 + (NOA) and nitrate (NO 3 -) in the arugula leaves increased linearly with the nitrogen doses. However, it is noteworthy that the NO 3 -levels were below the maximum permissible level for the cultivation of vegetables under greenhouse conditions.

The use of crop rotation and manure application can provide sustainability for an agricultural production system by improving soil quality and increasing nutrient use efficiency. This study aimed to evaluate the effect of mineral, organic and mineral+organic fertilization on grain yield and on soil phosphorus and potassium balance, in two crop systems under no-till, with and without rotation of cover crops. The experiment was carried out from 2006 to 2008 on a clayey Rhodic Hapludox in Marechal Cândido Rondon, Paraná State, Brazil. The cropping sequence in the rotation system involving cover crops was black oat + hairy vetch + forage turnip/corn/pigeon pea/wheat/mucuna + brachiaria + sunn hemp, and in the succession system was wheat/corn/wheat/soybean. Organic and mineral+organic fertilizations consisted of the application of solely manure and manure combined with mineral fertilizer, respectively. Soil P and K balances were calculated after the second year of the experiment, up to a depth of 0.40 m. First year corn yields were higher in the crop succession system accompanied by mineral fertilization. In the second year, wheat and soybean yield did not vary between crop systems and nutrient sources, demonstrating the residual effect of crop rotation and manure use. Crop rotation with cover crops resulted in an increase in soil K levels by promoting the recycling of this nutrient in the soil. In both crop systems, the application of mineral and organic fertilizers -either in isolation or in combinationresulted in a negative soil P and K balance in the short term. This represents a threat to the sustainability of the agricultural production system in the long term, due to the depletion of soil nutrient reserves. Key words: Organic fertilization, fertilizer, cover crops, soil nutrient, no-till Resumo A utilização de rotação de culturas e a aplicação de esterco pode conferir sustentabilidade ao sistema de produção agrícola, por melhorar a qualidade do solo e aumentar a eficiência de uso de nutrientes. O objetivo deste trabalho foi avaliar o efeito da adubação mineral, orgânica e mineral+orgânica na produtividade de grãos e no balanço de fósforo e de potássio no solo em dois sistemas de culturas sob plantio direto, com e sem rotação de plantas de cobertura. O experimento foi conduzido em Marechal Cândido Rondon, Paraná, Brasil, de 2006 a 2008, em um Latossolo Vermelho. A sequência de culturas no sistema em rotação com plantas de cobertura foi aveia preta + ervilhaca + nabo/milho/guandu/trigo/ mucuna + braquiária + crotalária / milho, e no sistema em sucessão foi trigo/milho/trigo/soja/milho. As adubações, orgânica e mineral+orgânica consistiram, respectivamente, da aplicação de esterco e de esterco combinado com fertilizante mineral. O balanço de P e de K no solo foi avaliado, após o segundo ano de condução do experimento, na camada de 0,0-0,40 m de profundidade. A produtividade do milho, no primeiro ano, foi superior na sucessão de culturas e na adubação mineral. No segundo ano, a produtividade de trigo e de ...

ABSTRACT. Tillering plays an important role in wheat yield potential and it is affected by genotype and environmental conditions. This work aimed to study the effects of phosphorus levels on tiller emergence, survival and contribution to yield potential of two wheat cultivars. The experiment was carried out under greenhouse conditions in Botucatu, São Paulo State, Brazil. A 2 x 5 factorial randomized block design with four replications was applied. Two wheat cultivars (IAC 370 and IAC 375) and five phosphorus levels (0, 150, 300, 450 and 600 mg dm -3 ) were evaluated in pots with 10 dm 3 of a clayey Oxisol. Higher P levels increased tiller emergence, survival and yield, especially for secondary tillers. Tiller abortion levels were higher in IAC 370 cultivar whereas retention of formed tillers was higher in IAC 375.

Brachiaria spp. have been grown in a variety of cropping systems and are often terminated with herbicides, which may cause nitrogen (N) loss from the soil-plant system. In this study ammonia (NH 3-N) loss by shoots and N balance in a soil-plant system were determined after desiccation of palisade grass (Brachiaria brizantha (Hochst. ex A. Rich) Stapf, cv. Marandu), signalgrass (Brachiaria decumbens Stapf), humidicola (Brachiaria humidicola (Rendle) Schweick) and Congo grass (Brachiaria ruziziensis Germain et Evrard). The grasses were grown in pots filled with an Oxisol in a greenhouse. Sixty days after planting, the plants were desiccated with glyphosate. Analyses were performed on plant and soil at desiccation and then at 7, 14, 21 and 28 days after desiccation in order to assess NH 3-N losses by shoots and to estimate the N balance in the system. Total nitrogen (Total-N) concentration in shoots and roots of brachiarias decreased after desiccation, thereby reducing the amount of N in plants of the four brachiaria species. However, as most of the N lost by plants was released into the soil, N losses from the soil-plant system were small compared with the total N in the system: 1.2, 0.5, 0.4 and 1.4% for palisade grass, signalgrass, humidicola and Congo grass, respectively. N losses as NH 3 from the soil-plant system after desiccation with glyphosate varied among brachiaria species, ranging from 0.8 to 2.0 g m −2 kg −1 , and accounted for 30-80% of total loss.

Background Nitrate leaching is a primary pathway of nitrogen loss from agricultural systems, and is affected by both tillage and cropped species. However, there is little information on conservation systems without nitrogen fertilization. Methods Nitrate leaching was assessed in soybean (Glycine max) cropped in rotation with the following cover crops under no-till and chiseling: ruzigrass (Brachiaria ruziziensis), grain sorghum (Sorghum bicolor), pearl millet (Pennisetum glaucum), forage sorghum (Sorghum bicolor), Sunn hemp (Crotalaria juncea), triticale (X Triticosecale) and sunflower (Helianthus annuus). Results Ruzigrass and grain sorghum cropped in the fall/winter resulted in similar NO 3 − leaching, which was greater under sunflower than under triticale, likely due to high N uptake and immobilization in plant residues. Sunn hemp as a spring crop resulted in higher NO 3 − leaching than pearl millet at two locations and forage sorghum at one location likely due to a higher N input by biological fixation. Millet resulted in the lowest N leaching by depleting the soil solution. Chiseling/ fallow resulted in higher nitrogen leaching as compared with non-fixing N cover crops.Conclusions Even when N is not applied, it is important to intensify cropping systems in tropical environments using cover crops with vigorous root systems and high N demand, which prevent N leaching, as well as provides N to the following crop as the straw is mineralized.