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Native to subtropical region of South America, yerba mate is responsive to P under some conditions, but the degree of influence of genetic and soil on the growth and composition of the leaf is unknown. The aim of study was to evaluate plant growth, nutrients and potentially toxic elements in leaves of yerba mate clones in response to P application in acid soils. In greenhouse condition, two yerba mate clone seedlings were grown (210 days) in pots, each clone in a completely randomized design in factorial scheme (with and without P; four acid soils). The elemental composition of leaves and the growth of plants were determined. Phosphorus promoted plant growth, but this was not accompanied by increased P in leaf tissue in all conditions tested. The P effect on the elemental composition varied: decrease/null (N, K, Mg, Mn, Cu, Ni, B, Mo, Al, Cd); increase/null (C/N, C, Ca, Fe, V); increase/decrease/null (Zn, Ba, Pb) and; null (Cr). The soils affect the elemental composition of the leaves, especially Mn, with accumulation greater than 1000 mg kg -1 . The Ba, Pb, Al and Zn in the leaves varied among clones. Yerba mate response to P was affected by edaphic and plant factors.

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Digital terrain models (DTM) have been used in soil mapping worldwide. When using such models, improved predictions are often attained with the input of extra variables provided by the use of proximal sensors, such as magnetometers and portable X-ray fluorescence scanners (pXRF). This work aimed to evaluate the efficiency of such tools for mapping soil classes and properties in tropical conditions. Soils were classified and sampled at 39 locations in a regular-grid design with a 200-m distance between samples. A pXRF and a magnetometer were used in all samples, and DTM values were obtained for every sampling site. Through visual analysis, boxplots were used to identify the best variables for distinguishing soil classes, which were further mapped using fuzzy logic. The map was then validated in the field. An ordinary least square regression model was used to predict sand and clay contents using DTM, pXRF and the magnetometer as predicting variables. Variables obtained with pXRF showed a greater ability for predicting soil classes (overall accuracy of 78% and 0.67 kappa index), as well as for estimating sand and clay contents than those acquired with DTM and the magnetometer. This study showed that pXRF offers additional variables that are key for mapping soils and predicting soil properties at a detailed scale. This would not be possible using only DTM or magnetic susceptibility.

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Anibal de MORAES 7 RESUMOA grande maioria do rebanho brasileiro de bovinos é criado a pasto e apresenta baixa produtividade, dado pelo baixo suprimento e qualidade das pastagens. O objetivo foi avaliar a produtividade e composição química do Capim Mombaça (Panicum maximum) sob doses crescentes de nitrogênio. O experimento foi conduzido na Estação Experimental do Cangüiri localizada em Pinhais-PR, pertencente à Universidade Federal do Paraná. O delineamento experimental foi o de blocos ao acaso com quatro repetições e cinco tratamentos (0, 85, 170, 320 e 510 kg de N ha -1 ) aplicados a lanço em novembro de 2007. Os parâmetros avaliados foram produtividade de matéria seca (MS), teor de clorofila na folha e concentrações totais de N e C. A pastagem obteve incrementos na produção de MS, teor de clorofila e concentração total de N. A adubação nitrogenada propiciou incrementos lineares na produção de MS e PB, variando de 585 a 10.310 e de 45 a 1.279 kg ha -1 , após 85 e 161 dias da aplicação, respectivamente. Os incrementos na produtividade de matéria seca foram lineares com 19 kg de MS para cada kg de N aplicado. Cada kg de N também propiciou as seguintes variações lineares: 0,5x10 -5 mg kg -1 de N -teor de clorofila, 0,015 g kg -1 de N -concentração de N; 2,52 kg kg -1 de N -PB; 7,98 kg kg -1 de N -C total, e -0,025 -relação C/N. A adubação nitrogenada aumentou a produtividade, bem como as concentrações de PB e clorofila, além de diminuir a relação C/N. Palavras-chave: produtividade; forrageira; nitrogênio; clorofila. ABSTRACTThe majority of Brazilian livestock is raised under pasture which usually has low productivity. This is due to both low biomass offer and low quality of pastures. The objective of this study was to evaluate the Nitrogen fertilization on yield and quality of Mombaça grass (Panicum maximum cv. Mombaça). The experiment was carried out at Canguiri Experimental Station located Pinhais county-Parana state, belonging to Federal University of Paraná. An oxissol with high organic matter content, low acidic, and without limitation of available P and K was used for the study. The experimental design was a randomized complete block with four replications and five N rate treatments (0, 85, 170, 320 e 510 kg of N ha -1 ) applied broadcast in the first week of November 2007. The pasture was evaluated for yield dry matter (DM), chlorophyll leaf contents, and total concentration of nitrogen and carbon. The nitrogen fertilization resulted in great improvement on DM and protein yield, varying from 585 to 10.310 and from 45 to 1279 kg ha -1 , after 85 and 161 days fertilization application, respectively. The DM increment showed to be linear with 19 kg DM for each kg N applied. Each kg N applied also provided the following linear variation: 0,5x10 -5 mg kg -1 -chlorophyll leaf content; 0,015 g kg -1 -N concentration; 2,52 kg ha -1 -total protein yield; 7,98 kg ha -1 total C yield, and -0,025 -C/N ratio. The nitrogen fertilization enhanced productivity and forage quality for developed grass under good condition of s...

Consumed by populations in South America, Araucaria angustifolia seeds have received little study regarding elemental composition and nutritional value. Thirty-five seed sites from subtropical Brazil were sampled and seed concentrations of C,