Fertilización del kiwi (Actinidia deliciosa (A. Chev.) C. F. Liang & A. R. Ferguson, cv. Hayward) durante la etapa de implantación en el sudeste bonaerense (Argentina)

En una plantación de kiwi situada en Balcarce (provincia de Buenos Aires, Argentina), se evaluó el efecto de la fertilización nitrogenada y potásica sobre el crecimiento de la planta durante la etapa de implantación, en la temporada 2008 - 2009. Los tratamientos fueron T: control sin fertilizar, N: fertilizado con nitrógeno (48 kg/ha N), K: fertilizado con potasio (60 kg/ha K) y NK: fertilizado con nitrógeno y potasio (48 kg/ha N - 60 kg/ha K). Se realizaron muestreos periódicos de: longitud de tallo, longitud del último entrenudo y área foliar. Se determinó el diámetro del tallo a fin de temporada y la distribución de raíces en el perfil de suelo en plena dormición. Se efectuaron análisis foliares de macronutrientes, así como N mineral, N anaeróbico (NAN) y carbono orgánico (CO) en el suelo. El suelo correspondió a un Argiudol, con niveles de NAN entre 85 - 100 mg/kg y de CO de 45 - 50 g/kg en los primeros 30 cm. Los resultados obtenidos, en cuanto al crecimiento de la parte aérea de la planta, no constituyen evidencia suficiente para justificar la fertilización con N y K bajo las condiciones experimentales del estudio. Aun en el T, los niveles foliares de N y K se mantuvieron dentro de los estándares normales. El sistema radical, observado durante el reposo, se habría visto beneficiado por la fertilización nitrogenada. En el estrato de suelo comprendido entre 10 y 20 cm se determinó un promedio de 61 raíces/100 cm2, en el tratamiento N, 40 en el tratamiento combinado NK, 28 en el tratamiento K, y 19 en el testigo.

Cultivo en maceta de Iris xiphium L. (Iris de Holanda) con diferentes concentraciones de humus de lombriz y sus lixiviados

Se evaluaron tres variedades de Iris xiphium L. cultivadas en maceta en cuatro proporciones de humus de lombriz y se aplicaron los lixiviados diluidos como bioabono foliar. El experimento se realizó en un diseño completamente al azar con arreglo trifactorial y se midieron ocho variables: longitud de tallo (LT), longitud de botón (LB), longitud de flor (LF), diámetro de botón (DB), diámetro de flor (DF), biomasa (B), área foliar (AF) y días de cosecha (DDC). Los resultados indicaron que la variedad Telstar resultó ser la más precoz. El mejor tratamiento en dicha variedad para las variables LT, LB, B, DF y DDC correspondió a la proporción 30/70 (% lombrihumus / % suelo) y la dilución 1:10 de lixiviado; el segundo mejor tratamiento fue en la variedad Discovery en la proporción 40/60 (%lombrihumus / %suelo) y dilución 1:10 de lixiviado para las variables LT, AF y B. El presente trabajo aporta nueva información en cuanto al uso de sustratos y abono foliar orgánicos para el manejo sustentable, con bajo impacto ambiental, en cultivos florícolas.

Respuesta al déficit hídrico en el crecimiento de forestales del bosque urbano de Mendoza : análisis comparativo en árboles jóvenes

El objetivo del trabajo fue evaluar la respuesta de plantas jóvenes de cuatro especies forestales urbanas a diferentes niveles de déficit hídrico. El ensayo se realizó en vivero, durante tres ciclos vegetativos, con plantas de Platanus x hispanica cv. acerifolia (plátano), Morus alba (morera), Fraxinus americana (fresno americano) y Acacia visco (visco). Los tratamientos de riego fueron: control (reposición del 100% transpirado); riego deficitario moderado (reposición del 66% transpirado) y riego deficitario severo (reposición del 33% transpirado). Las variables de respuesta evaluadas fueron altura, diámetro de tallos, área foliar y ancho de anillos de crecimiento. Las plantas bajo riego deficitario severo presentaron disminuciones en todos los parámetros de crecimiento considerados. Acacia visco resultó con crecimientos comparables al control, bajo riego deficitario equivalente al 66% del agua transpirada, con lo cual puede ser considerada especie de interés para forestaciones en condiciones de estrés hídrico moderado.

Sustrato y dosis de fertirriego en la aclimatización de vitroplantas de Agave americana var. oaxacencis

Con la finalidad de asegurar la adaptación en invernadero de plantas de Agave americana var. oaxacensis obtenidas in vitro, se evaluó el efecto de sustratos y dosis de fertirriego en la aclimatización y crecimiento de 180 plantas. Este trabajo se realizó en un invernadero del Instituto Tecnológico del Valle de Oaxaca, México, a principios de 2012. Se utilizaron plantas recién salidas del laboratorio. El experimento se estableció según el diseño completamente al azar con arreglo factorial 2 (sustratos: arena y perlita) x 5 (fertilización: 1, 25, 50, 75 y 100%). La unidad experimental fue una planta en un recipiente de plástico de 150 cm3 con 18 repeticiones. La fertilización se basó en la solución universal de Steiner y diariamente cada planta recibió a nivel de sustrato 10 mL durante 12 semanas. Se evaluó el crecimiento en hojas, tallo y raíz, realizando análisis de varianza y prueba de medias (Tukey, α = 0,05). Todas las plantas se adaptaron, pero aquellas plantas establecidas en perlita lograron los mejores crecimientos en área foliar, volumen de raíz, peso fresco total, materia seca de raíz y total de planta. El tamaño de las plantas al término de su aclimatación estuvo en relación con la cantidad de nutrimentos de la solución nutritiva.

Early Oligocene continental climate ofthe Paleogene Basin in Hungary and Slovenia

This paper concentrates on the Early Oligocene palaeoclimate of the southern part of Eastern and Central Europe and gives a detailed climatological analysis, combined with leaf-morphological studies and modelling of the palaeoatmospheric CO2 level using stomatal and d13 C data. Climate data are calculated using the Coexistence Approach for Kiscellian floras of the Palaeogene Basin (Hungary and Slovenia) and coeval assemblages from Central and Southeastern Europe. Potential microclimatic or habitat variations are considered using morphometric analysis of fossil leaves from Hungarian, Slovenian and Italian floras. Reconstruction of CO2 is performed by applying a recently introduced mechanistic model. Results of climate analysis indicate distinct latitudinal and longitudinal climate patterns for various variables which agree well with reconstructed palaeogeography and vegetation. Calculated climate variables in general suggest a warm and frost-free climate with low seasonal variation of temperature. A difference in temperature parameters is recorded between localities from Central and Southeastern Europe, manifested mainly in the mean temperature of the coldest month. Results of morphometric analysis suggest microclimatic or habitat difference among studied floras. Extending the scarce information available on atmospheric CO2 levels during the Oligocene, we provide data for a well-defined time-interval. Reconstructed atmospheric CO2 levels agree well with threshold values for Antarctic ice sheet growth suggested by recent modelling studies. The successful application of the mechanistic model for the reconstruction of atmospheric CO2 levels raises new possibitities for future climate inference from macro-flora studies.

(Table S3) Benthic foraminiferal Mg/Ca, Li/Ca and stable isotope ratios of ODP Site 122-761

The sensitivities of benthic foraminiferal Mg/Ca and Li/Ca to bottom water temperature and carbonate saturation state have recently been assessed. Here we present a new approach that uses paired Mg/Ca and Li/Ca records to calculate simultaneous changes in temperature and saturation state. Using previously published records, we first use this approach to document a cooling of deep ocean waters associated with the establishment of the Antarctic ice sheet at the Eocene-Oligocene climate transition. We then apply this approach to new records of the Middle Miocene Climate Transition from ODP Site 761 to estimate variations in bottom water temperature and the oxygen isotopic composition of seawater. We estimate that the oxygen isotopic composition of seawater varied by ~1 per mil between the deglacial extreme of the Miocene Climatic Optimum and the glacial maximum following the Middle Miocene Climate Transition, indicating large amplitude variations in ice volume. However, the longer-term change between 15.3 and 12.5 Ma is marked by a ~1°C cooling of deep waters, and an increase in the oxygen isotopic composition of seawater of ~0.6 per mil. We find that bottom water saturation state increased in the lead up to the Middle Miocene Climate Transition and decreased shortly after. This supports decreasing pCO2 as a driver for global cooling and ice sheet expansion, in agreement with existing boron isotope and leaf stomatal index CO2 records but in contrast to the published alkenone CO2 records.

Abundance patterns and isotopic signals of morphotypes of Globigerinoides ruber

The chemical composition of shells of the planktonic foraminifer Globigerinoides ruber (white) is frequently used to determine past sea surface conditions. Recently, it has been shown that arbitrarily defined morphotypes within this species exhibit different chemical and isotopic signatures. Here, we investigate the occurrence through time and in space of morphological types of G. ruber (white) in late Quaternary and Holocene sediments of the central and the eastern Mediterranean Sea. In 115 samples representing two distinct time intervals (MIS 1-2 and MIS 9-12) at ODP Site 964 and the piston core GeoTü-SL96, we have defined three morphological types within this species and determined their relative abundances and stable isotopic composition. A quantitative analysis of morphological variation within G. ruber (white) in four samples revealed that the subjectively defined morphotypes occupy separate segments of a continuous and homogenous morphospace. We further show that the abundance of the morphotypes changes significantly between glacials and interglacials and that the three morphotypes of G. ruber show significant offsets in their stable isotopic composition. These offsets are consistent within glacial and interglacial stages but their sign is systematically reversed between the two Sites. Since the isotopic shifts among the three G. ruber morphotypes are systematic and often exceed 1per mil, their understanding is essential for the interpretation of all G. ruber-based proxy records for the paleoceanographic development of the Mediterranean during the late Quaternary.

Responses of three tropical seagrass species to CO2 enrichment

Increased atmospheric carbon dioxide leads to ocean acidification and carbon dioxide (CO2) enrichment of seawater. Given the important ecological functions of seagrass meadows, understanding their responses to CO2 will be critical for the management of coastal ecosystems. This study examined the physiological responses of three tropical seagrasses to a range of seawater pCO2 levels in a laboratory. Cymodocea serrulata, Halodule uninervis and Thalassia hemprichii were exposed to four different pCO2 treatments (442-1204 µatm) for 2 weeks, approximating the range of end-of-century emission scenarios. Photosynthetic responses were quantified using optode-based oxygen flux measurements. Across all three species, net productivity and energetic surplus (PG:R) significantly increased with a rise in pCO2 (linear models, P < 0.05). Photosynthesis-irradiance curve-derived photosynthetic parameters-maximum photosynthetic rates (P max) and efficiency (alpha) also increased as pCO2 increased (linear models, P < 0.05). The response for productivity measures was similar across species, i.e. similar slopes in linear models. A decrease in compensation light requirement (Ec) with increasing pCO2 was evident in C. serrulata and H. uninervis, but not in T. hemprichii. Despite higher productivity with pCO2 enrichment, leaf growth rates in C. serrulata did not increase, while those in H. uninervis and T. hemprichii significantly increased with increasing pCO2 levels. While seagrasses can be carbon-limited and productivity can respond positively to CO2 enrichment, varying carbon allocation strategies amongst species suggest differential growth response between species. Thus, future increase in seawater CO2 concentration may lead to an overall increase in seagrass biomass and productivity, as well as community changes in seagrass meadows.

LiDAR simulation in modelled orchards to optimise the use of terretrial laser scanners and derived vegetative measures

Light detection and ranging (LiDAR) technology is beginning to have an impact on agriculture. Canopy volume and/or fruit tree leaf area can be estimated using terrestrial laser sensors based on this technology. However, the use of these devices may have different options depending on the resolution and scanning mode. As a consequence, data accuracy and LiDAR derived parameters are affected by sensor configuration, and may vary according to vegetative characteristics of tree crops. Given this scenario, users and suppliers of these devices need to know how to use the sensor in each case. This paper presents a computer program to determine the best configuration, allowing simulation and evaluation of different LiDAR configurations in various tree structures (or training systems). The ultimate goal is to optimise the use of laser scanners in field operations. The software presented generates a virtual orchard, and then allows the scanning simulation with a laser sensor. Trees are created using a hidden Markov tree (HMT) model. Varying the foliar structure of the orchard the LiDAR simulation was applied to twenty different artificially created orchards with or without leaves from two positions (lateral and zenith). To validate the laser sensor configuration, leaf surface of simulated trees was compared with the parameters obtained by LiDAR measurements: the impacted leaf area, the impacted total area (leaves and wood), and th impacted area in the three outer layers of leaves.

Importance of canopy porosity into vineyard and the relationship with the grape maturity. Digital estimation method

In warm and dry climates, the use of porous systems should be required in order to allow a better leaf distribution inside the plant, causing more space in the clusters area and enhancing determined physiological processes so in the leaf (photosynthesis, v entilation, transpiration) as in berry (growth and maturation). Plant geometry indexes, yield and must composition have been studied in three different systems: sprawl with 12 shoots/m (S1); sprawl system with 18 shoots/m (S2) and vertical positioned syste m or VSP with 12 shoots/m (VSP1). Total leaf area increases as the crop load does, whoever surface area depends on to two factors: crop load and the training system (VSP vs. sprawl), which can provide differences in leaf exposure efficiencies. The main objective of this study was to validate digital photography measurements used to compare porosity differences among treatments and, as they affect plant microclimate and, therefore, yield and berry quality. Also, all previous studied indexes (LAI, SA, SFEr) tended to overestimate the relationship between exposed leaf surface and porosity of each treatment, but the use of digital method proved to be an effective tool in order to assess canopy porosity. Results showed that not positioned and free systems (sprawl) scored between 25- 50% more porosity in the clusters area than the fixed vertical system (VSP), which resulted in a better plant microclimate for test conditions, mainly by improving the exposure of internal clusters and internal canopy ventilation. On the other hand, higher crop load treatment (S2) showed a real increase in yield (16%) without any relevant change into must composition, even improving total anthocyanin content into berry during ripening

Importance of canopy porosity into vineyard and the relationship with the grape maturity. Digital estimation method

In warm and dry climates, the use of porous systems should be required in order to allow a better leaf distribution inside the plant, causing more space in the clusters area and enhancing determined physiological processes so in the leaf (photosynthesis, ventilation, transpiration) as in berry (growth and maturation). Plant geometry indexes, yield and must composition have been studied in three different systems: sprawl with 12 shoots/m (S1); sprawl system with 18 shoots/m (S2) and vertical positioned system or VSP with 12 shoots/m (VSP1). Total leaf area increases as the crop load does, whoever surface area depends on to two factors: crop load and the training system (VSP vs . sprawl), which can provide differences in leaf exposure efficiencies. The main objective of this study was to validate digital photography measurements used to compare porosity differences among treatments and, as they affect plant microclimate and, therefore, yield and berry quality. Also, all previous studied indexes (LAI, SA, SFEr) tended to overestimate the relationship between exposed leaf surface and porosity of each treatment, but the use of digital method proved to be an effective tool in order to assess canopy porosity. Results showed that not positioned and free systems (sprawl) scored between 25 - 50% more porosity in the clusters area than the fixed vertical system (VSP), which resulted in a better plant microclimate for test conditions, mainly by improving the exposure of internal clusters and internal canopy ventilation. On the other hand, higher crop load treatment (S2) showed a real increase in yield (16%) without any relevant change into must composition, even improving total anthocyanin content into berry during ripening

Factors affecting berry composition of Tempranillo grapevines before the arrest of phloem transport.

It is already known that berry ripening is determined by the leaf area/fruit ratio, as well as temperature and leaf physiology. The aim of this work was to assess the influence of these parameters on Tempranillo cultivar throughout stage III of berry development.

CsRAV1: a candidate gene for improving lignocellulosic biomass yield

Fast-growing tree species of Populus spp.,Salix spp. and Eucalyptus spp. are cultivated to produce wood in a short time. Poplars are cultivated with cycles of 15-18 years to obtain saw timber and peeler logs, but when grown as short -rotation coppice(SRC) to produce biomass, planting density increases and rotation is considerably reduced (3-5 years). In this regard, research efforts are focused in the identification of traits and loci that allow the generation of improved SRC biomass-yielding genotypes. Biomass yield is a highly complex trait as it is the combined outcome of many other complex traits, each under separate polygenic control. Among profitable biomass yield-related traits are the amount of sylleptic branching and the length of winter dormancy. In poplar and in a few other Salicaceae species some lateral buds grow out sylleptically, the same season in which they form without the need of an intervening rest period. Sylleptic branching in poplar increases branch number, leaf area and general growth of the tree in its early years, and is a reasonable predictor of coppice yield. On the other hand, the length of winter dormancy determines the extent of the growth period. Our group has characterized the RAV1 gene of Castanea sativa (CsRAV1), encoding a transcription factor of the subfamily RAV (Related to ABI3/VP1). CsRAV1 expression shows a marked seasonal pattern, being higher in autumn and winter both in stems and buds. We generated transgenic lines of the hybrid clone Populus tremulax P. alba INRA 717 1B4 constitutively expressing CsRAV 1. These CsRAV1-expressing poplars develop sylleptic branches only a few weeks after potting. In addition to the sylleptic branching phenotype, these trees show phenological features that could give rise to an extended growth period. We are currently assessing the phenotype and behavior of these transgenic trees in a field trial, and ultimately, we will evaluate the impact on lignocellulosic biomass quality and production.