Effects of 59Fe, 65Zn and of three soil types on dry matter yield, chemical composition and nitrogen fixation in Phaseolus vulgaris L. cv. carioca

The aim of this work was to study in greenhouse conditions the effects of two levels of iron and zinc on yield and chemical composition of common bean (Phaseolus vulgaris L.) and on atmospheric nitrogen fixation, in three soils, classified as Terra Roxa Estruturada (TRE), Latossol Vermelho Escuro (LVE), and Podzolico Vermelho Amarelo (PVA). The coefficient of utilization of these micronutrients by this crop and its distribution in above-ground parts and roots were also assessed. The rates for iron were 1.5 and 3.0 ppm, and for zinc, 2.5 and 5.0 ppm. It was applied 7.5 µCi of 59Fe/kg of soil with the lower rate of the stable iron, and 5.0 and 10.0 µCi of Zn/kg of soil in the pots corresponding to the lower and higher rate of the stable zinc, respectively. The plants were harveste at the age of 60 days and nitrogen, phosphorus, potassium, iron and zinc contents were determined. Immediately after harvest, symbiotic nitrogen fixation was assessed, using the acetylene reduction method. The detection of 59Fe and 65zn radioactivity were carried out on nitric percloric extract, by gamma ray spectrometry. The behavior of common bean presented high variation among the three soils, for all the variables. There was no influence of treatments of iron and zinc on dry matter of above ground part and root and also on the weight and number of nodules. The rate of 3.0 ppm of iron decreased the capacity of nodules to fix atmospheric nitrogen in relation to rate of 1.5 ppm, while the rate of 5.0 ppm of zinc increased this capacity, in relation to the rate of 2.5 ppm. There was significative effect of treatments on nitrogen, potassium and zinc contents in above ground part and on nitrogen and zinc contents in the root. The absorption of zinc from the fertilizer and the percentagem of zinc in the plant derived from fertilizer were diretly influenced by rate of zinc The higher coefficient of utilization of zinc from the fertilizer was 4.0%.No presente trabalho, conduzido em casa de vegetação, procuramos estudar os efeitos dos micronutrientes ferro e zinco na produção de materia seca, composição química do feijoeiro (Phaseolus vulgaris L.) e na fixação do nitrogênio atmosférico, em três solos, classificados como Terra Roxa Estruturada (TRE), Latossol Vermelho Escuro (LVE) e Podzólico Vermelho Amarelo (PVA). Procuramos também determinar os índices de aproveitamento destes micronutrientes pelo feijoeiro e sua distribuição na parte aérea e na raiz. O delineamento experimental foi um fatorial 3x7, sendo três solos e sete tratamentos por solo, com três repetições. Nos tratamentos, foram utilizados duas doses de ferro e duas doses de zinco em separado ou combinando as doses menores e maiores destes micronutrientes (Fe1Zn1, Fe2Zn2). As doses de ferro foram 1,5 e 3,0 ppm e as de zinco foram 2,5 e 5,0 ppm. Foram aplicados 7,5 µCi de 59Fe/kg de solo nos vasos correspondentes à dose menor de ferro e 5,0 e 10,0 µCi de 65Zn/kg de solo nos vasos correspondentes respectivamente à dose menor e maior de zinco. Todos os tratamentos receberam uma adubação básica. O comportamento do feijoeiro apresentou grande variação entre os três tipos de solos, para todas as variáveis. Não houve influência dos tratamentos de ferro e zinco na produção de parte aérea e raiz e nem no peso e numero dos nodulos. A dose de 3,0 ppm de ferro diminuiu a capacidade dos nódulos de fixarem nitrogênio atmosférico em relação à dose de 1,5 ppm enquanto que a dose de 5,0 ppm de zinco aumentou esta capacidade, em relação à dose de 2,5 ppm. Houve um efeito significativo dos tratamentos na concentração de nitrogênio, potássio, ferro e zinco na parte aérea e na concentração de nitrogênio, e zinco na raiz. A absorção de zinco dos fertilizantes e a percentagem do zinco na planta proveniente do adubo foram influenciadas diretamente pelas doses de zinco. O maior coeficiente de aproveitamento do zinco do adubo foi de 4,0%

Regional and seasonal differences in light absorption by yellow substance in the Southern Bight of the North Sea

Absorption spectra (250-800 nm) of yellow substance were measured in 1993 and 1994 along five onshore-offshore transects in the Southern Eight of the North Sea in different seasons. All spectra had a common shape, so the amount of yellow substance could be established using one reference wavelength as a proxy variable. The exponential slope parameter at 380 nm (S) of the absorption spectra ranged from -0.016 to -0.023 per nm when regression was based upon the 250-650 nm wavelength range; values were 25% lower when fitting was performed over the more restricted waveband 360-540 nm, partly due to a minor shoulder at 260-275 nm in all spectra. The concentration of yellow substance, expressed as the absorption coefficient at 380 nm (a(380); m(-1)), varied over an order of magnitude, from low values down to 0.17 m(-1) in the English Channel, up to 1.00-1.25 m(-1) near the Rhine and Scheldt outflow, to maxima of up to 1.75 m(-1) in the neritic-estuarine waters at the entrance to the shallow Wadden Sea. This regional distribution pattern was in agreement with the known water-mass circulation and with the location of sources of yellow substance: highest concentrations close to the shore under the influence of freshwater inflow, lower values with increasing distance from the coast, where Atlantic Ocean water is the major water-mass component. No significant seasonal variation in yellow-substance concentration was found anywhere when a correction was applied for salinity. Extrapolation to zero salinity yielded an absorption coefficient at 380 nm of 5.38 m(-1) for the freshwater input at both the Texel and Walcheren transects, but of 3.29 m(-1) at the Noordwijk transect, reflecting differences in yellow-substance concentration between the Rhine, the Meuse, and Lake IJssel, as previously noted in fluorescence measurements. Yellow-substance concentration was not only correlated with salinity but also, albeit much less, with chlorophyll concentrations; the contribution of phytoplankton to the yellow-substance pool was marginal but significant. A relation appeared to exist between yellow-substance absorbance at 380 nm and yellow-substance fluorescence intensity; fluorescence measurements in the southern North Sea can be translated to absorption (more appropriate for ocean colour detection by remote sensing) by equating I mFl unit to an absorption coefficient at 380 nm of 0.056 m(-1), and using the exponential relation a(ys)(lambda) = a(ys)(lambda(ref)) exp(-S(lambda - lambda(ref))) for extrapolation to UV-Vis spectral absorption. (C) 1999 Elsevier Science B.V. All rights reserved

Testing evolutionary hypotheses about species borders: patterns of genetic variation towards the southern borders of two rainforest Drosophila and a related habitat generalist

Several evolutionary hypotheses help explain why only some species adapt readily to new conditions and expand distributions beyond borders, but there is limited evidence testing these hypotheses. In this study, we consider patterns of neutral (microsatellite) and quantitative genetic variation in traits in three species of Drosophila from the montium species group in eastern Australia. We found little support for restricted or asymmetrical gene flow in any species. In rainforest-restricted Drosophila birchii, there was evidence of selection for increased desiccation and starvation resistance towards the southern border, and a reduction in genetic diversity in desiccation resistance at this border. No such patterns existed for Drosophila bunnanda, which has an even more restricted distribution. In the habitat generalist Drosophila serrata, there was evidence for geographic selection for wing size and development time, although clinal patterns for increased cold and starvation resistance towards the southern border could not be differentiated from neutral expectations. These findings suggest that borders in these species are not limited by low overall genetic variation but instead in two of the species reflect patterns of selection and genetic variability in key traits limiting borders

Contrasting extreme long-distance migration patterns in bar-tailed godwits <i>Limosa lapponica</i>

Migrating birds make the longest non-stop endurance flights in the animal kingdom. Satellite technology is now providingdirect evidence on the lengths and durations of these flights and associated staging episodes for individual birds. Using thistechnology, we compared the migration performance of two subspecies of bar-tailed godwit Limosa lapponica travellingbetween non-breeding grounds in New Zealand (subspecies baueri) and northwest Australia (subspecies menzbieri) andbreeding grounds in Alaska and eastern Russia, respectively. Individuals of both subspecies made long, usually non-stop,flights from non-breeding grounds to coastal staging grounds in the Yellow Sea region of East Asia (average 10 060 ? SD290 km for baueri and 5860 ? 240 km for menzbieri). After an average stay of 41.2 ? 4.8 d, baueri flew over the North PacificOcean before heading northeast to the Alaskan breeding grounds (6770 ? 800 km). Menzbieri staged for 38.4 ? 2.5 d,and flew over land and sea northeast to high arctic Russia (4170 ? 370 km). The post-breeding journey for baueri involvedseveral weeks of staging in southwest Alaska followed by non-stop flights across the Pacific Ocean to New Zealand (11 690 kmin a complete track) or stopovers on islands in the southwestern Pacific en route to New Zealand and eastern Australia. Bycontrast, menzbieri returned to Australia via stopovers in the New Siberian Islands, Russia, and back at the Yellow Sea; birdstravelled on average 4510 ? 360 km from Russia to the Yellow Sea, staged there for 40.8 ? 5.6 d, and then flew another5680–7180 km to Australia (10 820 ? 300 km in total). Overall, the entire migration of the single baueri godwit with afully completed return track totalled 29 280 km and involved 20 d of major migratory flight over a round-trip journey of174 d. The entire migrations of menzbieri averaged 21 940 ? 570 km, including 14 d of major migratory flights out of 154 dtotal. Godwits of both populations exhibit extreme flight performance, and baueri makes the longest (southbound) andsecond-longest (northbound) non-stop migratory flights documented for any bird. Both subspecies essentially make singlestops when moving between non-breeding and breeding sites in opposite hemispheres. This reinforces the critical importanceof the intertidal habitats used by fuelling godwits in Australasia, the Yellow Sea, and Alaska