Adilson de Oliveira Junior

Marcha de absorção de macronutrientes na cultura do girassol

This study aimed to establish curves of macronutrient accumulation in sunflower. The experiment was conducted in the field on a Typic Hapludox, at the experimental station of Embrapa Soja in Londrina, State of Parana. The plots consisted of 14 25 m long rows spaced 0.70 m apart, resulting in a total area of 245 m2, with four replications. Prior to sowing a fertilization seeding of 300 kg ha-1 of 05-20-20 NPK fertilizer was applied. Fertilization was split in two applications of 25 + 1 kg ha-1 N and B, which were applied 21 and 35 days after sowing, respectively. The hybrid BRS 191 and a final plant density of 40,000 plants ha-1 were used. Plant samples were collected every two weeks after emergence and separated in the different parts (petioles, leaves, stems and, when applicable, capitula and achenes). After drying, each plant part was weighed and ground to determine the N, P, K, Ca, Mg, and S content. From the contents of these nutrients and dry mass of each plant, the accumulation curve was obtained. It was found that for yields > 3,000 kg ha-1, BRS 191 extracted about 150, 24, 286, 116, 42, and 24 kg ha-1 of N, P, K, Ca, Mg, and S, respectively, in the following order of extraction: K> N> Ca> P = S. In addition to the relation to exportation, the nutrient order was: N> P = K> S = Mg> Ca. Therefore, special attention should be paid to the maintenance of an adequate supply of N, K and Ca, due to the high demand of sunflower.

Características produtivas do trigo em função de fontes e doses de nitrogênio

Nitrogen fertilization is an important management practice in grasses and quite complex, due to several factors which influence it, such as climatic conditions, cropping systems and available levels and sources. This study aimed at evaluating the effect of topdressing nitrogen (N) sources and levels on the productive characteristics of wheat ( Triticum aestivum L.) grown after soybean, under no-till system. The experiment was conducted in an Oxisol, in Londrina, Parana State, Brazil. The experimental design was randomized blocks, in a 3x4 factorial scheme, with four replications. As topdressing N sources, urea, urea + urease inhibitor (NBPT) and polymer-coated urea were evaluated, in 2008, and urea, urea + urease inhibitor (NBPT) and ammonium sulfate, in 2009, in four doses (0.0 kg ha -1 , 40.0 kg ha -1 , 80.0 kg ha -1 and 120.0 kg ha -1 of N) applied 20 days after emergence. Plant height, lodging percentage, mass of 1,000 grains, grain yield and hectoliter mass were determined, and results showed that increased topdressing N levels promoted plants lodging, decreasing the mass of 1,000 grains, yield and hectoliter mass. The N sources did not affect the yield of the BRS Pardela cultivar grown after soybean.

Sunflower micronutrient uptake curves

Devido ao fato de a maioria dos trabalhos encontrados na literatura a respeito do acumulo dos micronutrientes [zinco (Zn), manganes (Mn), ferro (Fe), cobre (Cu) e boro (B)] no girassol serem antigos, objetiva-se, com este trabalho estabelecer curvas de acumulo de micronutrientes em um hibrido de girassol na condicao edafoclimatica dos tropicos. O experimento foi instalado no campo sobre Latossolo Vermelho distroferrico de textura argilosa, localizado na fazenda experimental da Embrapa Soja, em Londrina-PR, utilizando o hibrido comercial BRS 191. O delineamento experimental utilizado foi o inteiramente casualizado, com quatro repeticoes. As unidades experimentais foram constituidas de 14 linhas, com espacamento de 0,70 m entre linhas e 25 m de comprimento, com densidade final de 42.858 plantas ha-1. As amostras das plantas foram coletadas em intervalos de 14 dias apos a emergencia. Apos cada coleta, dividiram-se as plantas em peciolo, folha, caule, capitulo e aquenios, sendo que as mesmas foram secas ate peso constante, quando foram tomados os pesos da materia seca e determinados os teores de Zn, Mn, Fe, Cu e B no tecido vegetal. A absorcao de micronutrientes ocorreu em maior velocidade a partir dos 42 dias apos a emergencia (DAE). O Fe foi o micronutriente mais absorvido, acumulando maior quantidade tanto nos aquenios como em relacao ao total absorvido. O acumulo total de Fe, Mn, Zn, B e Cu foram 38,06, 19,68, 9,20, 8,62 e 4,27 mg planta-1, respectivamente.

EFICIÊNCIA AGRONÔMICA DE FOSFATOS DE ROCHA EM SOLO COM ELEVADO TEOR DE CÁLCIO TROCÁVEL

No Brasil, a maioria dos trabalhos sobre a aplicacao de fosfatos de rocha foi realizada em solos do Cerrado com pH menor que 5,5 e baixos teores de Ca trocavel. Estudos em condicoes diferentes dessa, alem de raros, tem sido desestimulados, pois esses solos podem apresentar-se restritivos a dissolucao dessas fontes, a depender da especie cultivada e da natureza geologica do fosfato aplicado. Um experimento para estudar a eficiencia agronomica dos fosfatos de Bayovar e Itafos, aplicados por meio da adubacao corretiva, foi implantado em um Cambissolo Haplico Ta eutrofico vertissolico de elevado teor de Ca trocavel e pH 6. O delineamento experimental utilizado foi em blocos ao acaso com parcelas subdivididas em faixas e quatro repeticoes. As parcelas consistiam de tres tratamentos de fosfatagem, na dose de 200 kg ha-1 de P2O5, com o Fosfato Natural Reativo de Bayovar, o Fosfato de Rocha Itafos e o superfosfato triplo (fonte de referencia), alem de um tratamento-padrao sem correcao de P. As subparcelas correspondiam aos tres niveis de adubacao de manutencao (0, 60 e 120 kg ha-1 de P2O5) aplicados anualmente no sulco de semeadura, utilizando superfosfato triplo. Cultivou-se milho nos dois anos em que o experimento foi conduzido (2011 e 2012). No periodo avaliado, a produtividade de graos e o teor de P foliar do milho indicaram menores necessidades de reposicao de P, por meio das doses de manutencao, conforme maior era a solubilidade da fonte corretiva aplicada. Tanto Mehlich-1 quanto a Resina de Troca Ionica Mista removeram mais P dos tratamentos em que foram aplicados fosfatos de rocha em relacao ao tratamento onde foi aplicado o superfosfato triplo via adubacao corretiva. Quando aplicados de maneira isolada (dose 0 de manutencao), os indices de eficiencia agronomica dos fosfatos de rocha foram de 72,08 e 82,31% para o Bayovar e de 43,85 e 47,47% para o Itafos nos anos de 2011 e 2012, respectivamente. No periodo avaliado, os tratamentos de maior economicidade foram a fosfatagem com o superfosfato triplo nas doses de manutencao de 0 e 60 kg ha-1 de P2O5 e a com o fosfato reativo de Bayovar, nas doses de 60 e 120 kg ha-1 de P2O5.

OPTIMUM RATIO OF CALCIUM AND BORON IN THE NUTRIENT SOLUTION OR IN CASTOR BEAN SHOOT FOR FRUIT YIELD AND SEED OIL CONTENT

Calcium (Ca) and boron (B) have been reported as the major macro- and micronutrient required for castor bean plant yield. The objective of this study was to determine the Ca:B ratios (in the growth media and plant tissue) for fruit yield and shoot dry weight of the castor bean (Ricinus communis L.), grown in a nutrient solution, and to evaluate Ca and B supply on concentration and total uptake of Ca, potassium (K), magnesium (Mg), and B, as well on the seed oil content. The treatments were arranged in a 3 × 3 factorial fashion, consisting of three rates of Ca (40, 80, and 160 mg L−1) and three of B (0.32, 0.96, and 1.60 mg L−1). Calcium and B rates increased the shoot and root dry weight and fruit yield at a Ca:B ratio in the nutrient solution of 166 and 100, respectively. Symptoms of B deficiency were observed in plants supplied with 0.32 mg B L−1, regardless of the Ca concentration in the nutrient solution. Plants which showed visual symptoms of Ca deficiency cultivated with 40 mg Ca L−1 presented concentration of Ca in plant tissue up to 10 g kg−1. The concentration and total Ca and B uptake increased with the rates of them. Notwithstanding, the shoot Ca accumulation was improved by B rates. In addition, there were no decreases in K and Mg uptake due to Ca rates. Furthermore, addition of 80 mg L−1 of Ca and 1.60 mg L−1 of B in the growth media increased the seed oil content. The Ca:B ratio in the diagnostic leaf associated with the highest plant dry weight (shoot and root) and fruit yield, was 500 (16 to 20 g kg−1 of Ca, and for 30 to 40 mg kg−1 of B).