The olive tree: a paradigm for drought tolerance in Mediterranean climates

Olive trees (<i>Olea europaea</i> L.) are commonly grown in the Mediterranean basin where prolonged droughts may occur during the vegetative period. This species has developed a series of physiological mechanisms, that can be observed in several plants of the Mediterranean macchia, to tolerate drought stress and grow under adverse climatic conditions. These mechanisms have been investigated through an experimental campaign carried out over both irrigated and drought-stressed plants in order to comprehend the plant response under stressed conditions and its ability to recover. Experimental results show that olive plants subjected to water deficit lower the water content and water potentials of their tissues, establishing a particularly high potential gradient between leaves and roots, and stop canopy growth but not photosynthetic activity and transpiration. This allows the continuous production of assimilates as well as their accumulation in the various plant parts, so creating a higher root/leaf ratio if compared to well-watered plants. Active and passive osmotic adjustment due to the accumulation of carbohydrates (in particular mannitol and glucose), proline and other osmolytes have key roles in maintaining cell turgor and leaf activities. At severe drought-stress levels, the non-stomatal component of photosynthesis is inhibited and a light-dependent inactivation of the photosystem II occurs. Finally, the activities of some antioxidant enzymes involved in the scavenging of activated oxygen species and in other biochemical pathways increase during a period of drought. The present paper provides an overview of the driving mechanisms adopted by olive trees to face drought stress with the aim of better understanding plant-soil interactions

Actores sociales y perspectiva de continuidad de los tambos asociados a cooperativas de la zona de Rosario.

A partir de la demanda de La Sociedad Cooperativa de Tamberos de la Zona de Rosario Ltda. en donde se requiere la participación de la Facultad de Ciencias Agrarias (UNR), para la elaborar un programa conjunto, que oriente a los productores tamberos en la toma de decisiones tecnológicas, para mejorar la calidad de vida de los mismos y favorecer su permanencia en el sector productivo. Se realiza un estudio con actividades en los tambos pertenecientes a dicha cooperativa. Se considera que la tecnología, como interacción social de conocimientos, forma parte de las bases de innovación participativas en que el aprender es beneficio para productores/as, entidades, estudiantes y docentes. En las actividades se prioriza: 1) la realización de un relevamiento y diagnóstico participativo de las unidades de producción junto a productores y sus familias 2) la elaboración de un plan de trabajo acordado entre los participantes; 3) la capacitación permanente de los productores y estudiantes participantes del proyecto; 4) la vinculación de los productores y estudiantes avanzados de Agronomía para mejorar su formación profesional. En esta comunicación, se reflexiona en cómo favorecer vínculos entre entidades de la zona de influencia de la UNR y la valorización de investigación-extensión como proceso con relación a campos interdisciplinarios que requieren ser fortalecidos para el desarrollo sustentable. Haciendo especial énfasis en los actores sociales del proceso como lo son la mano de obra y la estructura familiarDichio, Lucian

The exploration-exploitation paradigm for networked biological systems

The stochastic exploration of the configuration space and the exploitation of functional states underlie many biological processes. The evolutionary dynamics stands out as a remarkable example. Here, we introduce a novel formalism that mimics evolution and encodes a general exploration-exploitation dynamics for biological networks. We apply it to the brain wiring problem, focusing on the maturation of that of the nematode C. elegans. We demonstrate that a parsimonious maxent description of the adult brain combined with our framework is able to track down the entire developmental trajectory

Sustainable apricot orchard management to improve soil fertility and water use efficiency

This 4-year on-farm study reports the effects of different agricultural practices on yield and carbon input in an apricot orchard grown in Mediterranean area. Groups of plants under local orchard management (LOM) practices (i.e., soil tillage, removing of pruning residues, mineral fertilisers) were compared with plots under sustainable orchard management (SOM) actions (i.e., cover crop, no-tillage, compost application, mulching of pruning residues). In the SOM blocks, fertilization was based on plant demand and soil availability and irrigation volumes were calculated on the evapotranspiration values basis, while in the LOM plots fertilization and irrigation were empirically managed. Results show that yield was enhanced by 28% by SOM. In comparison with LOM plots, changed practices increased the amount of N, P, K annually incorporated into soil thus increasing their reservoir in the soil. The study demonstrates that appropriate crop management can increase the mean annual carbon soil inputs from about 1.5 t ha-1 to 9.0 t ha-1 per year

Statistical models of complex brain networks: a maximum entropy approach

The brain is a highly complex system. Most of such complexity stems from the intermingled connections between its parts, which give rise to rich dynamics and to the emergence of high-level cognitive functions. Disentangling the underlying network structure is crucial to understand the brain functioning under both healthy and pathological conditions. Yet, analyzing brain networks is challenging, in part because their structure represents only one possible realization of a generative stochastic process which is in general unknown. Having a formal way to cope with such intrinsic variability is therefore central for the characterization of brain network properties. Addressing this issue entails the development of appropriate tools mostly adapted from network science and statistics. Here, we focus on a particular class of maximum entropy models for networks, i.e. exponential random graph models (ERGMs), as a parsimonious approach to identify the local connection mechanisms behind observed global network structure. Efforts are reviewed on the quest for basic organizational properties of human brain networks, as well as on the identification of predictive biomarkers of neurological diseases such as stroke. We conclude with a discussion on how emerging results and tools from statistical graph modeling, associated with forthcoming improvements in experimental data acquisition, could lead to a finer probabilistic description of complex systems in network neuroscience.Comment: 34 pages, 8 figure

Integration of the regulated deficit irrigation strategy in a sustainable orchard management system

Irrigation in arid regions requires special attention to optimize the management of all components of the orchard system in order to increase water use efficiency and reduce environmental impacts (e.g. soil salinization, degradation of ground and surface waters). This six-year study reports the comparison of some orchard practices (soil and irrigation management, plant nutrition) routinely adopted by local farmers (conventional, C) with those interventions having the potential to save water and maximize water use efficiency in a peach orchard and therefore defined as sustainable (S). Due to the relative approach (C versus S) used in this study, classical statistical comparison of results could not be made. The S system included the application of regulated deficit irrigation (RDI) with specific crop coefficients to calculate the plant water requirement. The S system on average saved 1450 m3 ha-1 of water per year without affecting yield or fruit quality. The concept of economic water productivity (EWP) is discussed. We conclude that addressing some practices currently adopted by farmers could increase sustainability of irrigation and enhance (EWP) in peach tree orchards

Soil Fungi-Plant Interaction

Computer modelling & simulatio