Search

Critical influence of different level of shade on the underlying physiological and biophysical limitations of an important pulse crop pigeonpea [(Cajanas cajan (L.)] has been investigated. The crop was grown under three level of shade intensity 33% (S1), 50% (S2), 75% (S3) based on the incident sunlight intensity as obtained through providing different category of shade-net in shade-net house facilities and the open field (open) without shade. Major impact has been observed on photosynthetic CO2 assimilation (Amax), leaf water use efficiency (WUEi), photosynthetic radiation use efficiency (PRUE) and biophysical constraints relating to photosynthetic light energy utilization. Efficiency of the crop for light energy utilization has been assessed through chlorophyll fluorescence traits for Photosystem II (PSII) functioning, leaf level physio-biophysical indicators and the leaf spectral traits. The functional traits were responsible for the critical impact of shade causing limitation to get maximum potential performance of the crop. Amax was noted 22.58 µ mol CO2 m−2 s−1 in open sun light grown plants (Open) whereas, 19.91, 13.03 and 7.20 at S1, S2 and S3 level of shade respectively. In comparison to open, transpiration rate (E) declined by only 4.6% at S1 level of shade whereas it substantially decreased by 44.4% and 68.3% at S2 and S3 level of shade respectively. Differential reduction in the physiological and leaf biophysical responses depending on the intensity of shade suggested that the physiological functioning of the crop has been progressively diminished over and above the S1. Electron transport rate across PSII (ETR) marginally reduced at S1 by 10.65% while it progressively decreased at S2 (31.07%) and S3 (55.17%) level of shade in comparison to open. The findings have clearly revealed that the limitation of electron supplies through PSII and their inefficient utilization for driving the photosynthetic carbon acquisition were the major limiting factors for achieving the potential performance of the crop under shade. The results would be useful for searching for better crop to cope with the limitation of shade through achieving shade-tolerance or shade-resilience in crops for agroforestry importance. The present work offers a perspective as to how different intensity of shades impair the various aspects involving the important pulse crop i.e. pigeonpea which will further improve our understanding of the functional importance of the physiological and biophysical processes involved to alleviate the major constraints posed by shade. Further, the present study has revealed that about 33% shade (S1) based on the incident sun light, can be a critical limit for the crop as the deep (S2) and extreme (S3) shade has highly detrimental effects on the physiology of the crop which remarkably affects the grain yield production. [ABSTRACT FROM AUTHOR]

Molecular and fossil evidence suggests that complex eukaryotic multicellularity evolved during the late Neoproterozoic era, coincident with Snowball Earth glaciations, where ice sheets covered most of the globe. During this period, environmental conditions—such as seawater temperature and the availability of photosynthetically active light in the oceans–likely changed dramatically. Such changes would have had significant effects on both resource availability and optimal phenotypes. Here, we construct and apply mechanistic models to explore (i) how environmental changes during Snowball Earth and biophysical constraints generated selective pressures, and (ii) how these pressures may have had differential effects on organisms with different forms of biological organization. By testing a series of alternative—and commonly debated—hypotheses, we demonstrate how multicellularity was likely acquired differently in eukaryotes and prokaryotes owing to selective differences on their size due to the biophysical and metabolic regimes they inhabit: decreasing temperatures and resource availability instigated by the onset of glaciations generated selective pressures towards smaller sizes in organisms in the diffusive regime and towards larger sizes in motile heterotrophs. These results suggest that changing environmental conditions during Snowball Earth glaciations gave multicellular eukaryotes an evolutionary advantage, paving the way for the complex multicellular lineages that followed. [ABSTRACT FROM AUTHOR]

Abstract Growing industrial crops on marginal lands has been proposed as a strategy to minimize competition for arable land and food production. In the present study, eight experimental sites in three different climatic zones in Europe (Mediterranean, Atlantic and Continental), seven advanced industrial crop species [giant reed (two clones), miscanthus (M. × giganteus and two new seed‐based hybrids), saccharum (one clones), switchgrass (one variety), tall wheatgrass (one variety), industrial hemp (three varieties) and willow (eleven clones)], and six marginality factors alone or in combination (dryness, unfavorable texture, stoniness, shallow soil, topsoil acidity, heavy metal and metalloid contamination) were investigated. At each site, biophysical constraints and low‐input management practices were combined with prevailing climatic conditions. The relative yield of a site‐specific low‐input system compared with the site‐specific control was from small to large (i.e. from −99% in industrial hemp in the Mediterranean to +210% in willow in the Continental zone), due to the genotype‐by‐management interaction along with climatic variation between growing seasons. Genotype selection and improved knowledge on crop response to changing environmental, site‐specific biophysical constraint and input application has been detected as key to profitably grow industrial crops on marginal areas. This study may act to provide hints on how to scale up investigated cropping systems, through low‐input practices, under similar environmental and soil conditions tested at each site. However, further attention to detail on the agronomy of early plant development and management in larger multi‐year and multi‐location field studies with commercially scalable agronomies are needed to validate yield performances, and thereby to inform on the best industrial crop options.

Identifying the general principles by which genotypes are converted into phenotypes remains a challenge in the post-genomic era. We still lack a predictive understanding of how genes shape interactions among cells and tissues in response to signalling and environmental cues, and hence how regulatory networks generate the phenotypic variation required for adaptive evolution. Here, we discuss how techniques borrowed from synthetic biology may facilitate a systematic exploration of evolvability across biological scales. Synthetic approaches permit controlled manipulation of both endogenous and fully engineered systems, providing a flexible platform for investigating causal mechanisms in vivo. Combining synthetic approaches with multi-level phenotyping (phenomics) will supply a detailed, quantitative characterization of how internal and external stimuli shape the morphology and behaviour of living organisms. We advocate integrating high-throughput experimental data with mathematical and computational techniques from a variety of disciplines in order to pursue a comprehensive theory of evolution. This article is part of the theme issue 'Genetic basis of adaptation and speciation: from loci to causative mutations'. [ABSTRACT FROM AUTHOR]

Growing industrial crops on marginal lands has been proposed as a strategy to minimize competition for arable land and food production. In the present study, eight experimental sites in three different climatic zones in Europe (Mediterranean, Atlantic and Continental), seven advanced industrial crop species [giant reed (two clones), miscanthus (M. × giganteus and two new seed‐based hybrids), saccharum (one clones), switchgrass (one variety), tall wheatgrass (one variety), industrial hemp (three varieties) and willow (eleven clones)], and six marginality factors alone or in combination (dryness, unfavorable texture, stoniness, shallow soil, topsoil acidity, heavy metal and metalloid contamination) were investigated. At each site, biophysical constraints and low‐input management practices were combined with prevailing climatic conditions. The relative yield of a site‐specific low‐input system compared with the site‐specific control was from small to large (i.e. from −99% in industrial hemp in the Mediterranean to +210% in willow in the Continental zone), due to the genotype‐by‐management interaction along with climatic variation between growing seasons. Genotype selection and improved knowledge on crop response to changing environmental, site‐specific biophysical constraint and input application has been detected as key to profitably grow industrial crops on marginal areas. This study may act to provide hints on how to scale up investigated cropping systems, through low‐input practices, under similar environmental and soil conditions tested at each site. However, further attention to detail on the agronomy of early plant development and management in larger multi‐year and multi‐location field studies with commercially scalable agronomies are needed to validate yield performances, and thereby to inform on the best industrial crop options. Growing industrial crops on marginal lands has been proposed as a strategy to minimize competition for arable land and food production. This study can bring an advancement to knowledge on the suitability of certain industrial crops to marginal and contaminated soils to mitigate indirect land‐use change (i‐LUC) in accordance with the RED II and to meet the European Green Deal towards an EU climate neutral in 2050. It ultimately can assist to make general recommendations of the most appropriate crop and management options at the different regions, climates, soils and marginal land types. [ABSTRACT FROM AUTHOR]

Agricultural land abandonment due to biophysical and socioeconomic constraints is increasing across Europe. Meanwhile there is also an increase in bioenergy demand. This study assessed woody crop performance on several relevant types of marginal agricultural land in Europe, based on field experiments in Latvia, Spain and Ukraine. In Latvia, hybrid aspen was more productive than birch and alder species, and after eight years produced 4.8 Mg ha−1 y−1 on stony soil with sandy loam texture, when best clone and treatment combination was selected. In Spain, Siberian elm produced up to 7.1 Mg ha−1 y−1 on stony, sandy soil with low organic carbon content after three triennial rotations. In Ukraine, willow plantations produced a maximum of 10.8 Mg ha−1 y−1 on a soil with low soil organic carbon after second triennial rotation. The productivity was higher when management practices were optimized specifically to address the limiting factors of a site. Longer rotations and lower biomass yields compared to high-value land can be expected when woody crops are grown on similar marginal agricultural land shown in this study. Future studies should start here and investigate to what extent woody crops can contribute to rural development under these conditions. [ABSTRACT FROM AUTHOR]

Organisms are subject to the laws of physics, so the process of evolution by genetic variation and natural selection is constrained by these fundamental laws. Classic and recent studies of the biophysical limits facing organisms have shown how fundamental physical constraints can be used to predict broad-scale relationships between body size and organismal biomechanics and physiology. These relationships often take the form of power laws across a wide range of body sizes for organisms sharing a common body plan. However, such biophysical perspectives have not been fully connected with the detailed dynamics of evolution by natural selection, nor with the variation between species around the central scaling relationships. Here we first discuss what a general biophysical theory of evolution would require and provide a mathematical framework for constructing such a theory. We discuss how the theory can predict not only scaling relationships, but also of identifying the types of tradeoffs made by different species living in particular niches. In addition, we discuss how a key higher-order requirement of a biophysical theory of evolution is its ability to predict asymptotic behavior and the limits of a particular body plan. We use several examples to illustrate how dominant physical constraints can be used to predict the minimum and maximum body sizes for a particular body plan, and we argue that prediction of these limits is essential for identifying the dominant physical constraints for a given category of organisms. Our general framework proposes that a major portion of fitness should be the overlay of how all traits of a particular body plan interact with fundamental physical constraints. To illustrate this concept, we investigate multiple physical limits on particular traits, such as insect legs, and show how the interaction of a number of traits determines the size limits on entire body plans, such as those of vascular plants. We use bacteria as an example of the shifts in which physiological traits and physical constraints are most limiting at various organism sizes. Finally, we address the effects of environmental conditions and ecological interactions in determining which of the physical constraints faced by organisms are most likely to affect their growth, survival, and reproduction, and hence their fitness. We consider such ecological effects on our examples of bacteria, insects, mammals and trees, and we nest the constraints-perspective in the broader picture of evolutionary processes.

The life histories of animals reflect the allocation of metabolic energy to traits that determine fitness and the pace of living. Here, we extend metabolic theories to address how demography and mass-energy balance constrain allocation of biomass to survival, growth, and reproduction over a life cycle of one generation. We first present data for diverse kinds of animals showing empirical patterns of variation in life-history traits. These patterns are predicted by theory that highlights the effects of 2 fundamental biophysical constraints: demography on number and mortality of offspring; and mass-energy balance on allocation of energy to growth and reproduction. These constraints impose 2 fundamental trade-offs on allocation of assimilated biomass energy to production: between number and size of offspring, and between parental investment and offspring growth. Evolution has generated enormous diversity of body sizes, morphologies, physiologies, ecologies, and life histories across the millions of animal, plant, and microbe species, yet simple rules specified by general equations highlight the underlying unity of life. [ABSTRACT FROM AUTHOR]

World biofuel production has been increasing to improve energy security and mitigate global warming. Southern Africa's bioenergy demand could increase with South Africa's planned fuel blending mandates, triggering increased demand for feedstocks and agricultural land. Ensuring sustained production will require a full understanding of the constraints to production expansion, considering the tradeoffs that may be generated in rural areas, as has been observed for large-scale land acquisitions. We analyse the social and biophysical constraints to biofuel production expansion in Zambia. Previously social constraints have received limited attention even though they may prove more problematic. Results indicate that Zambia is at least moderately suitable for bioenergy investments with biophysically suitable areas largely coinciding with the socially suitable areas. However, existing gaps in compensatory procedures may inhibit large-scale projects' access to development finance if not aligned with internationally acceptable practices, and generate negative outcomes if safeguards are not in place. [ABSTRACT FROM AUTHOR]

First paragraphs: This special issue of the Journal of Agriculture, Food Systems and Community Development highlights the best of the 2014 Food Systems Summit held at the University of Vermont. The Summit focused on local-level responses to globalization through the following themes: the impact of our geopolitical context on our food system, the biophysical constraints we face for food production globally, and the implications of behavior and culture for our food system. Using a format of refereed presentations and keynote speakers, and allowing for a dialogue between and among scholars, practitioners, policy makers, community activists and interested citizens, the Summit provided a space for lively pushing of the envelope by highlighting constraints and problems with our current food system and offering thoughtful, evidence-based solutions for improvement. Several presenters took the opportunity to go through the referee process. Five of those papers are included in this special issue, along with three commentaries written by the three keynote speakers. What is unique about the UVM Food Summit is the complex web of inquiry, discussion, openness, and questioning of the status quo by stakeholders in the food movement who don't often come together in the same venue. Conversing about one of the presentations or at the Taste of Vermont reception held on one evening of the Summit, one might find the Vermont secretary of agriculture interacting with a full or assistant professor, a staffer for U.S. Senator Patrick Leahy or Bernie Sanders, the executive director of Vermont's Farm to Plate initiative, and a dairy producer or small vegetable grower. In order to foster change that can improve working conditions of farm workers, provide tasty and healthy meals to schoolchildren, improve the economic conditions of farmers, and insure food access for now and into the future it is necessary for a wide range of actors to have a seat at the same table on an equal basis. That was and remains the goal of the annual UVM Food Systems Summit. What made the 2014 Summit even more meaningful was its place as a preconference event to the joint meeting of the Agriculture, Food and Human Values Society (AFHVS) and the Association for the Study of Food and Society (ASFS)—further expanding the audience across many disciplines as well as organizations....

Meeting human needs while sustaining the planet's life support systems is the fundamental challenge of our time. What role sustenance of biodiversity and contrasting ecosystem services should play in achieving a sustainable future varies along philosophical, cultural, institutional, societal, and governmental divisions. Contrasting biophysical constraints and perspectives on human well-being arise both within and across countries that span the tropics and temperate zone. Direct sustenance of livelihoods from ecosystem services in East Africa contrasts with the complex and diverse relationships with the land in Mexico and the highly monetary-based economy of the United States. Lack of understanding of the contrasting contexts in which decision-making about trade-offs occurs creates impediments to collective global efforts to sustain the Earth's life support systems. While theoretical notions of the goals of sustainability science seek a unified path forward, realities on the ground present challenges. This Special Feature seeks to provide both an analytical framework and a series of case studies to illuminate impediments posed to sustainability by contrasting biophysical constraints and human perspectives on what should be sustained. The contributors aim to clarify the trade-offs posed to human welfare in sustaining biodiversity and ecosystem services and the challenges in managing for a sustainable future in which human well-being is not compromised as compared to today. Our goal is to provide novel insights on how sustainability can be achieved internationally through exploration of constraints, trade-offs, and human values examined at multiple scales, and across geographic regions from a range of cultural perspectives. [ABSTRACT FROM AUTHOR]

Abstract: The natural world consists of hierarchical levels of complexity that range from subatomic particles and molecules to ecosystems and beyond. This implies that, in order to explain the features and behavior of a whole system, a theory might be required that would operate at the corresponding hierarchical level, i.e. where self-organization processes take place. In the past, biological research has focused on questions that could be answered by a reductionist program of genetics. The organism (and its development) was considered an epiphenomenona of its genes. However, a profound rethinking of the biological paradigm is now underway and it is likely that such a process will lead to a conceptual revolution emerging from the ashes of reductionism. This revolution implies the search for general principles on which a cogent theory of biology might rely. Because much of the logic of living systems is located at higher levels, it is imperative to focus on them. Indeed, both evolution and physiology work on these levels. Thus, by no means Systems Biology could be considered a ‘simple’ ‘gradual’ extension of Molecular Biology. [Copyright &y& Elsevier]

The northwestern hot arid region of India has been classified in 15 resource management domains (RMDs) by integrating biophysical resources and socio-economic indicators. Each RMD is uniform with respect to the natural resource base and socio-economic indicators, thus, these have similar potential/constraints and social status. The RMDs, (1) Western dune complex-livestock based livelihood, (2) Hard pan soil-livestock based livelihood, (10) Coastal rocky upland-labor based livelihood, and (11) Coastal ranns and mud flats-labor based livelihood, have severe biophysical constraints and low socio-economic status. The RMDs with moderate biophysical constraints and medium socio-economic status are (3) Sandy plain-rainfed farming and livestock, (4) Eastern sandy plain under rainfed/limited tube well irrigation, (5) Luni basin alluvial plain rainfed/brackish water irrigation, (6) Luni-Banas pediment-rainfed/limited dug-well irrigation, (12) Kachchh mainland-rainfed/limited irrigation (13) Santhalpur aeo-alluvial plain-rainfed farming, (14) Basaltic rocky/gravelly upland rainfed farming/labor based livelihood, and (15) Basaltic piedmont/valley fill with rainfed/limited irrigation. The RMDs associated with negligible biophysical constraints and high socio-economic status are (7) Dune complex with limited canal irrigation, (8) Canal irrigated aeolian plain, and (9) Intensive canal irrigated Sutlej-Yamuna river plain. Priority areas for research and development of each RMD have been suggested. Change analysis with respect to land use, area under different crops, and crop production revealed that the region is heading towards intensification and higher yields. [ABSTRACT FROM AUTHOR]

This paper proposes and implements biophysical constraints to select a unique solution to the bioelectromagnetic inverse problem. It first shows that the brain''s electric fields and potentials are predominantly due to ohmic currents. This serves to reformulate the inverse problem in terms of a restricted source model permitting noninvasive estimations of Local Field Potentials (LFPs) in depth from scalp-recorded data. Uniqueness in the solution is achieved by a physically derived regularization strategy that imposes a spatial structure on the solution based upon the physical laws that describe electromagnetic fields in biological media. The regularization strategy and the source model emulate the properties of brain activity''s actual generators. This added information is independent of both the recorded data and head model and suffices for obtaining a unique solution compatible with and aimed at analyzing experimental data. The inverse solution''s features are evaluated with event-related potentials (ERPs) from a healthy subject performing a visuo-motor task. Two aspects are addressed: the concordance between available neurophysiological evidence and inverse solution results, and the functional localization provided by fMRI data from the same subject under identical experimental conditions. The localization results are spatially and temporally concordant with experimental evidence, and the areas detected as functionally activated in both imaging modalities are similar, providing indices of localization accuracy. We conclude that biophysically driven inverse solutions offer a novel and reliable possibility for studying brain function with the temporal resolution required to advance our understanding of the brain''s functional networks. [Copyright &y& Elsevier]

Agroecozones are geographic areas that share similar biophysical characteristics for crop production, such as soil, landscape, and climate, which define the potentials for agricultural productivity. Delineation and characterization of agroecozones would greatly enhance agricultural decision-making and management, as well as the extrapolation of experiment station research and field trials to forms and landscapes of similar agronomic behavior. Currently, agroecozones are often represented with static and rigid boundaries derived by using data obtained by averaging observations over a period of time. The boundaries of these regions, however, are fuzzy and reflect change over time and space. Furthermore, the measurements used as the basis of the delineation are themselves uncertain. Agroecozones may be obtained by treating the input data as well as the resultant regions as fuzzy. Clustering is one of the most common approaches to derive agroecozones delineation. In this paper, we explore the suitability of some fuzzy clustering approaches for this problem. Experimental results show that fuzzy algorithms generate more accurate delineations as measured by their closeness to the Major Land Resources Areas (MLRA) map. However, they both require greater computational resources. Some additional advantages of using a fuzzy approach are also illustrated. This approach should be viewed as an additional tool available for modeling and analysis of important processes in spatial environmental decision support systems. [Copyright &y& Elsevier]

The cultivation of bioenergy crops could be considered as sustainable; however, its use in fertile lands could conflict with food production. The general purpose of this study is to identify areas where traditional food crops are not economically sustainable, but where they could be substituted by energy crops without changing the land use in Spain. We studied the profit margin of the main crops of the country, which are wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.), the spatial location of the growing areas, and the biophysical constraints. Spain has an extended area of 9.93 million hectares, with biophysical and/or economic constraints in rainfed arable areas. Grain yields ≤1.5 Mg ha−1 are not profitable; low organic matter content is the principal biophysical constraint. The average results showed a potential of 83.33 GJ ha−1 using triticale (x Triticosecale) and 174.85 GJ ha−1 using cardoon (Cynara cardunculus L.) in arable marginal lands. The production of biomass in this area would serve to cover between 3%–5% of primary energy needs in Spain for triticale or cardoon. In this respect, establishing energy crops in marginal lands could be an instrument to enhance rural development, boost the bio-economy, and reach environmental targets. [ABSTRACT FROM AUTHOR]

Capacitance limits the bandwidth of engineered and biological electrical circuits because it determines the gain-bandwidth product (GBWP). With a fixed GBWP, bandwidth can only be improved by decreasing gain. In engineered circuits, an inductance reduces this limitation through shunt peaking but no equivalent mechanism has been reported for biological circuits. We show that in blowfly photoreceptors a voltage-dependent K + conductance, the fast delayed rectifier (FDR), produces shunt peaking thereby increasing bandwidth without reducing gain. Furthermore, the FDR's time constant is close to the value that maximizes the photoreceptor GBWP while reducing distortion associated with the creation of a wide-band filter. Using a model of the honeybee drone photoreceptor, we also show that a voltage-dependent Na + conductance can produce shunt peaking. We argue that shunt peaking may be widespread in graded neurons and dendrites., (© 2016 The Author(s).)