No abstract

The development of smartphones, specifically their cameras, and imaging technologies has enabled their use as sensors/measurement tools. Here we aimed to evaluate the applicability of a fast and noninvasive method for the estimation of total chlorophyll (Chl), Chl a, Chl b, and carotenoids (Car) content of soybean plants using a smartphone camera. Single leaf disc images were obtained using a smartphone camera. Subsequently, for the same leaf discs, a Chl meter was used to obtain the relative index of Chl and the photosynthetic pigments were then determined using a classic method. The RGB, HSB and CIELab color models were extracted from the smartphone images and correlated to Chl values obtained using a Chl meter and by a standard laboratory protocol. The smartphone camera was sensitive enough to capture successfully a broad range of Chl and Car contents seen in soybean leaves. Although there was a variation between color models, some of the proposed regressions (e.g., the S and b index from HSB and Lab color models and NRI [RGB model]) were very close to the Chl meter values. Based on our findings, smartphones can be used for rapid and accurate estimation of soybean and Car contents in soybean leaves.

Recebido em 18/8/09; aceito em 13/3/10; publicado na web em 20/7/10 CHARACTERIZATION OF CHEMICAL ELEMENTS IN SOIL SUBMITTED TO DIFFERENT SYSTEMS USE AND MANAGEMENT BY ENERGY DISPERSIVE X-RAY FLUORESCENCE SPECTROMETRY (EDXRF). This study aimed to evaluate the chemical elements levels in soil, submitted to different management systems and use by the Energy Dispersive X-Ray Fluorescence Spectrometry -EDXRF. The systems were T1 -agro forestry (SAF), T2 -Native Field (CN), T3 -Native Forest (NM), T4 -Tillage Forest (PF); T5 -conventional tillage system (SPC) and T6 -System tillage (NT). Samples were collected at 0-10 and 10-20 cm, dried and ground for analysis in EDX-720. The soil showed no difference in the average concentrations of chemical elements analyzed in the profiles, but the systems presented different concentrations of metal elements, and T3 had the highest K, Ca and Zn at 0-10 cm and higher contents of K, Ca, Cu, Zn and Mn in the layer of 10-20 cm.Keywords: metals in soil; chemical elements; energy dispersive X-ray fluorescence spectrometry. INTRODUÇÃONos últimos anos, tem-se intensificado a necessidade da adoção de sistemas de uso e manejo do solo que preservem ou promovam melhorias em suas características físicas, químicas e biológicas. Isto se deve ao aumento da população mundial e, em decorrência, à maior demanda por alimentos, gerando a necessidade de maior produtividade nas áreas agricultáveis.1 Desta forma, intensifica-se a importância de escolher sistemas mais adequados de uso e manejo do solo, que contribuam para a melhoria de suas qualidades agronô-micas, assim mantendo ou alterando ao mínimo suas características e propriedades. 2,3A fertilidade do solo é um dos fatores que mais pode sofrer modificações, em função do uso e manejo do solo. Rachwal et al. 4 destacam que a maioria dos solos do Brasil é pobre em nutrientes, porém as matas nativas não apresentam sintomas de deficiência nutricionais, em virtude da ciclagem dos nutrientes, estando esses em perfeito equilíbrio com as demandas.Em relação aos sistemas agrícolas, são muitos os estudos que demonstram modificações químicas no solo entre eles destaca-se o de Muzilli, 5 que encontrou maior acúmulo de nutrientes nas camadas superficiais em plantio direto, quando comparado ao convencional. Silva e Silveira 1 apontam que os sistemas agrícolas afetam a distribuição de nutrientes no perfil do solo, ocorrendo maior concentração nas camadas superficiais naqueles em que houve menor movimentação de solo. Em sistemas florestais, Rachwal et al. destacam que a substituição de florestas naturais por plantios florestais de ciclo rápido altera os processos naturais de ciclagem e armazenamento de nutrientes, em razão, sobretudo, das mudanças na qualidade da matéria orgânica, causadas pelas práticas de manejo. 4 Cientes das possíveis modificações nos níveis de nutrientes que um solo sob diferentes uso e manejo pode apresentar, e que o conhecimento da fertilidade dos solos cultivados é um dos fatores primordiais para a obtenção de sucesso na atividade agrí...

Genetic diversity and path analysis of soybeans cultivars evaluated by means of quantitative descriptorsIn addition to the evaluations among genotypes, the use of multivariate techniques enables to restrict errors, mainly concerning genetic diversity, and therefore to predict combinations with greater heterotic effect, and the greater possibility of recovery of superior genotypes. The objective of this study was to evaluate the genetic divergence between 18 soybean cultivars based on six morphological characteristics. Path analysis was performed to verify the contribution of direct and indirect characters on grain yield. The Mahalanobis distance has founded techniques of both Tocher Method and dendrogram by Single Linkage. Five different groups were formed: with nine genotypes considered similar among them; while the cultivars CEP 59, Netuno and Urano formed groups isolated by the two grouping methods. The path analysis showed that the indirect characters had little influence on grain yield, with significant direct relationship with mass of 100 grain, and cultivars Tertulha and CEP 53 standing out with grain yields above 3.7 t.ha-¹. Dissimilaridade genética e análise de trilha de cultivares de soja avaliada por meio de descritores quantitativosAlém das avaliações entre genótipos, a utilização de técnicas multivariadas possibilita restringirem-se os erros, principalmente quanto à diversidade genética, podendo-se, assim, prever combinações com maior efeito heterótico, além da maior possibilidade de recuperação dos genótipos superiores. Objetivou-se, com este trabalho, avaliar a divergência genética entre 18 cultivares de soja, por meio de seis caracteres morfoagronômicos. Foi realizada a análise de trilha, para averiguar as contribuições direta e indireta desses caracteres sobre o rendimento de grãos. A distância generalizada de Mahalanobis fundamentou as técnicas de agrupamentos, tanto a de Tocher, bem como a do dendrograma por ligação simples. Observaram-se cinco grupos divergentes, sendo nove genótipos considerados similares entre si, enquanto os cultivares CEP 59, Netuno e Urano foram formadores de grupos isolados pelos dois métodos de agrupamento. Quanto à análise de trilha, observou-se que os caracteres indiretos pouco influenciaram o rendimento de grãos, tendo relação direta significativa com massa de 100 grãos, tendo-se destacado os cultivares Tertulha e CEP 53, com produtividade de grãos acima de 3,7 t ha-¹.Palavras-chave: agrupamento, Glycine max (L.) Merr., divergência genética.

R ESU M OObjetivou-se, com o presente trabalho, relacionar pigmentos fotossintéticos extraídos de modo clássico em laboratório com leituras obtidas pelo clorofilômetro portátil ClorofiLOG 1030, em folhas de gergelim, por meio de modelos matemáticos. O trabalho foi realizado em dezembro de 2010, na Embrapa Algodão, de onde foram retirados discos foliares de gergelim para serem mensurados os índices de clorofila por meio do clorofilômetro portátil. Os discos foliares foram submetidos à extração dos pigmentos fotossintéticos, utilizando-se 5 mL de dimetilsulfóxido (DMSO) e mantidos em banho-maria a 70 ºC, durante 30 min; depois foram retirados 3 mL de alíquota para a leitura em espectrofotômetro nos comprimentos de onda de 470, 646 e 663 nm. Com base nos resultados analíticos modelos matemáticos foram ajustados utilizando-se o índice de clorofila na predição dos teores de clorofila a, b e total e dos carotenóides e suas relações. Concluiu-se que o medidor portátil de clorofila ClorofiLOG 1030 pode ser utilizado na estimativa da concentração dos pigmentos fotossintéticos em folhas de gergelim com alta precisão, além de proporcionar economia de recursos e tempo. Palavras-chave: clorofilômetro, clorofila, calibraçãoNon destructive analysis of photosynthetic pigments in leaves of Sesamum indicum (L.)A B ST R A C T The study aimed to relate the photosynthetic pigments, which were extracted in a laboratory and the readings were obtained by the portable chlorophyll meter ClorofiLOG 1030, by using mathematical models in sesame leaves. This work was conducted in December 2010, at Embrapa Cotton, where feaf discs were removed to measure chlorophyll indexes through the portable chlorophyll meter. The same leaf discs were subjected to extraction of photosynthetic pigments, by using 5 mL dimethyl sulfoxide (DMSO), and were kept in a water bath at 70 ºC for 30 min. Afterwards, an aliquot of 3 mL was removed to be read in a spectrophotometer at wavelengths of 470, 646 and 663 nm. Based on analytical results, mathematical models were adjusted by using the chlorophyll index to predict the levels of chlorophyll a, b, and total, and of carotenoids and their relationships. The study concluded that the portable chlorophyll meter ClorofiLOG 1030 can be used to estimate the concentration of photosynthetic pigments in sesame leaves with high precision, besides saving resources and time.

In addition to improving sustainability in cropping systems, the use of a spring and winter crop rotation system may be a viable option for mitigating soil CO 2 emissions (ECO 2 ). This study aimed to determine short-term ECO 2 as affected by crop rotations and soil management over one soybean cycle in two no-till experiments, and to assess the soybean yields with the lowest ECO 2 . Two experiments were carried out in fall-winter as follows: i) triticale and sunflower were grown in Typic Rhodudalf (TR), and ii) ruzigrass, grain sorghum, and ruzigrass + grain sorghum were grown in Rhodic Hapludox (RH). In the spring, pearl millet, sunn hemp, and forage sorghum were grown in both experiments. In addition, in TR a fallow treatment was also applied in the spring. Soybean was grown every year in the summer, and ECO 2 were recorded during the growing period. The average ECO 2 was 0.58 and 0.84 g m 2 h −1 with accumulated ECO 2 of 5,268and 7,813 kg ha -1 C-CO 2 in TR and RH, respectively. Sunn hemp, when compared to pearl millet, resulted in lower ECO 2 by up to 12 % and an increase in soybean yield of 9% in TR. In RH, under the winter crop Ruzigrazz+Sorghum, ECO 2 were lower by 17%, although with the same soybean yield. Soil moisture and N content of crop residues are the main drivers of ECO 2 and soil clay content seems to play an important role in ECO 2 that is worthy of further studies. In conclusion, sunn hemp in crop rotation may be utilized to mitigate ECO 2 and improve soybean yield.

Sustainability of agriculture with no-tillage (NT) production requires appropriate cover cropping and not a simple and random approach of any cover crop species. However, relatively little is known of the long-term soil surface impacts of different cover crops in rotation with soybean (Glycine max) under NT in the tropics. We evaluated the impacts of different cover crops on soil aggregation, soil organic carbon (C) and nitrogen (N) fractions, and soil microbial activity of a Typic Rhodudalf at the end of 12 years under NT in São Paulo state of Brazil. Treatments included main plots during the winter dry season (triticale [× Triticosecale] and sunflower [Helianthus annuus]) and subplots during the spring cover crop season (pearl millet [Pennisetum glaucum], sunn hemp [Crotolaria juncea], forage sorghum [Sorghum bicolor], and fallow with occasional chiseling). All eight of these treatments followed soybean in summer. Winter crop treatments had no effect on soil aggregation, but total organic C and N concentrations were greater (p < 0.05) with triticale than with sunflower. Across depths, soil aggregation and soil C and N fractions were generally enhanced when sunn hemp was cover crop than with fallow in the spring. Triticale followed by sunn hemp provided soil cover and fresh mineralizable residue for improving soil quality in this unfertilized (N) soybean-based cropping system. Our results suggest that maintaining soil cover is important to improve soil aggregation and soil C and N fractions, but also the quality of organic inputs determined by cover crop species is an important factor controlling the dynamics of these soil responses.

This study was carried out in the Parque Municipal das Araucárias, located in the municipality of Guarapuava (PR) from May (06) to April (07). Its aim was to investigate which plants are used by Megachile (Moureapis) sp in provisioning of larvae, and to verify if this bee is oligolectic or polilectic. The collection of the plants was carried out during the bees activity period and in an area covering a 500 m radius from where the nests had been built. A sample of pollens from founded nests and from flowers was used to make permanent slides using the acetolysis method and with the aid of a light microscope, all pollen grains were examined in order to identify the plants used by this bee. A total of 80 pollen grain slides, from 16 nests were analysed. Although 99 plants were collected close to the bee's nesting site, in nest slides, the pollen of Ludwigia peruviana (36%) and Ludwigia sericea (63.6%) (Onagraceae) accounted for 99.6% of the total amount of pollen collected. With these results we are able to conclude that Megachile (Moureapis) sp is an oligolectic species and that these plants species are their important pollen source.Keywords: Ludwigia peruviana, Ludwigia sericea, Megachile (Moureapis) sp., provisioning. Plantas usadas por