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The objective of this work was to characterize the accumulation of carbon (C) and nitrogen (N), and the translocation of wheat (Triticum aestivum L.) cultivars to achieve both high-quality and high-yield. Twenty-four wheat cultivars, including 12 cultivars containing high-quality gluten subunit 5 + 10 at Glu-D1, and 12 cultivars with no Glu-D1 5 + 10, were planted at Yuanyang and Xuchang in Henan Province, during 2016–2017, and 2017–2018 cropping seasons. Wheat cultivars containing Glu-D1 5 + 10 had an advantage in grain quality traits. Significant difference (P < 0.05) was observed for grain protein concentration (GPC) between 5 + 10 group and no 5 + 10 group. Grain yield (GY) was significantly correlated with kernel number (KN) (r = 0.778, P < 0.01), thousand-kernel weight (TKW) (r = 0.559, P < 0.01), dry matter accumulation at post-anthesis (r = 0.443, P < 0.05), and stem water-soluble carbohydrate (WSC) accumulation (r = 0.487, P < 0.05) and translocation amount (r = 0.490, P < 0.05). GPC, dough stability time (DST) and nitrogen agronomic efficiency (NAE) were significantly correlated with nitrogen accumulation (NAA) at maturity stage (r = 0.524, = 0.404, = 0.418, P < 0.01, < 0.05, < 0.05, respectively), and nitrogen translocation amount (r = 0.512, = 0.471, = 0.405, P < 0.05, < 0.05, < 0.05, respectively). These results suggest that good-quality, high-yield, and high-efficiency could achieve through the selection of high-quality wheat cultivars and coordination of C and N accumulation and translocation. High-quality gluten subunit gene Glu-D1 5 + 10 and stem WSC could be used as a selection index for breeding and production of high-quality and high-yield wheat. [ABSTRACT FROM AUTHOR]

Under future climates, leaf temperature (Tl) will be higher and more variable. This will affect plant carbon (C) balance because photosynthesis and respiration both respond to short‐term (subdaily) fluctuations in Tl and acclimate in the longer term (days to months). This study asks the question: To what extent can the potential and speed of photosynthetic acclimation buffer leaf C gain from rising and increasing variable Tl? We quantified how increases in the mean and variability of growth temperature affect leaf performance (mean net CO2 assimilation rates, Anet; its variability; and time under near‐optimal photosynthetic conditions), as mediated by thermal acclimation. To this aim, the probability distribution of Anet was obtained by combining a probabilistic description of short‐ and long‐term changes in Tl with data on Anet responses to these changes, encompassing 75 genera and 111 species, including both C3 and C4 species. Our results show that (a) expected increases in Tl variability will decrease mean Anet and increase its variability, whereas the effects of higher mean Tl depend on species and initial Tl, and (b) acclimation reduces the effects of leaf warming, maintaining Anet at >80% of its maximum under most thermal regimes. Under future climates, leaf temperatures will be higher and more variable, with effects on the plant carbon balance. This study asks the question: To what extent can leaf net photosynthesis acclimate to buffer leaf carbon gains from rising and increasingly variable leaf temperatures? A probabilistic description of short‐ and long‐term changes in leaf temperature is parameterized by means of a dataset on net photosynthetic responses to these changes, encompassing 75 genera and 111 species. Our results show that (a) the expected increases in leaf temperature variability have always detrimental effects on leaf performance, whereas the effects of higher mean leaf temperatures depend on the species and initial temperature, and (b) acclimation greatly reduces the consequences of leaf warming. [ABSTRACT FROM AUTHOR]

We examined the combined effects of temperature, carbon dioxide (CO2) and watering regime during seed maturation on subsequent germinability and total phenolics of Arabidopsis thaliana [wild-type (WT) and abi1-1 mutant] seeds. Mature seeds were collected from plants that were grown under lower (22/18°C, 16 h light and 8 h dark) or higher (28/24°C, 16 h light and 8 h dark) temperatures, at ambient (400 μmol mol–1) or elevated (700 μmol mol–1) CO2 concentration, and well-watered or water-stressed. Germinated and non-germinated (viable, rotten and empty) seed percentages, germination rate and total phenolics were determined for both genotypes. Higher maturation temperatures increased seed germination percentage, but decreased germination rate, percentage of rotten and non-germinated viable seeds, and total phenolics. Elevated CO2 increased seed total phenolics. Water stress decreased the percentage of non-germinated viable seeds. Neither of the two latter factors affected other measured parameters. Seeds of the abi1-1 mutant had higher total phenolics. The fate of seeds was mostly affected by higher temperatures and water stress. Also, seeds of the abi1-1 mutant had higher germination rate, empty seed percentage and total phenolics than seeds of the WT genotype. Germination percentage was highest for the WT seeds that matured on the water-stressed plants that were grown under higher temperatures at ambient CO2. It can be concluded that higher temperatures had highest effects on seed germinability and other parameters, and elevated CO2 did not alleviate the negative effects of higher temperatures on seed viability. [ABSTRACT FROM AUTHOR]

Plant roots are generally considered to decompose slower than shoots and contribute more to accumulation of soil organic matter, and management history is expected to shape the structure and function of decomposer communities in soil. Here we study the effect of chemical characteristics of shoots and roots from fodder radish (Raphanus sativus oleiformis L.), a widely used cover crop, on the release of their C and N after addition to soil. Shoots and roots were incubated for 180 d at 20°C using four soils with different management histories (organic versus mineral fertiliser, with and without use of cover crops), and the release of CO2 and extractable mineral N was determined. More shoot C than root C was mineralised during the first 10 d of incubation. After 180 d, 58% of the C input was mineralised with no difference between shoots and roots. At the end of incubation, shoots had released more N (42% of shoot N) than roots (28% of root N). Moreover, management history did not affect net mineralisation of added plant C. Residues incubated in soil with a management history involving cover crops showed an enhanced net N mineralisation. Therefore, long-term decomposition of C added in radish shoots and roots is unaffected by differences in chemical characteristics or soil management history. However, the net mineralisation of N in shoots is faster than for N in roots, and net N mineralisation of added materials is higher in soil with than without a history of cover crops. [ABSTRACT FROM AUTHOR]

A carbon balance model (VitiSim) was used for assessing the effects of vine water status and different climate scenarios on the dry matter production and partitioning of ‘Tempranillo’ grapevines ( Vitis vinifera L.) grown in two different Spanish regions. Inputs included weather daily variables, stem water potential measurements and vineyard system data. Partitioning is based on the supply and demand balance using relative sink strength coefficients when carbon supply is lower than organ demands. A new routine to consider the effect of vine water status on photosynthesis rate was implemented in the model. Experimental data from two Spanish locations, several seasons (2007–2011) and well-watered and water-stressed vines were used for validating the model. A sensitivity analysis showed that model outputs are greatly influenced by those inputs linked to light interception. Simulated dry matter productions were realistic even though in general the amounts were underestimated. VitiSim was able to reproduce the effect of water stress on dry matter production observed in the field. Then, the model was used to estimate vine dry mass in different locations within Spain and worldwide under the standard current meteorological condition and under two climate change scenarios. Results were in accordance with those commonly found in field studies. Hence, this model appears useful to estimate vine dry matter potential from few easily available inputs and to simulate the effects of deficit irrigation strategies on grape yield. Further routines must be implemented to enhance VitiSim predictive capabilities and reliability. [ABSTRACT FROM AUTHOR]

Increases in carbon dioxide (CO2) and temperature are expected to induce complex effects on plant pathogens. The results of studies on the effects of climate change on a number of pathosystems, such as the downy and powdery mildew of grapevines, and on several pathogens of vegetable crops, such as rocket, basil, beet and zucchini, have been analysed in this review. In the reviewed works, plants were grown in controlled environment facilities (phytotrons) under six different simulated climatic conditions: a standard CO2 concentration (400-450 ppm) with a standard (ranging from 18 to 22/24 °C) and elevated temperature (5 °C higher than standard), and elevated CO2 (800-850 ppm) under a standard and elevated temperature. When the CO2 level and the temperature were increased, an increase was observed of powdery mildew on zucchini, Alternaria leaf spot on rocket salad, black spot and downy mildew on basil, Allophoma tropica on lettuce and Phoma leaf spot on garden beet. Variable effects were instead observed when individual climate parameters were taken into consideration. The effects of changed environmental values on some physiological parameters on the production of mycotoxins as well as on disease management were also considered on selected pathosystems. CO2 concentration and temperature proved to influence disease severity and mycotoxin production in different ways. As far as the application of biocontrol agents is concerned, the efficacy of Ampelomyces quisqualis against zucchini powdery mildew was found to be improved under higher temperature and CO2 conditions. The results obtained with different host/pathogen combinations will allow to develop adaptation strategies for disease management and to provide the seed industry with useful information in order to develop new cultivars that will be more adapted/adaptable to the changing conditions. The usefulness and limitations of studies carried out under controlled environment conditions are critically discussed. [ABSTRACT FROM AUTHOR]

Abstract: Carbon storage in forests and its ability to offset global greenhouse gas emissions, as well as biodiversity and its capacity to support ecosystem functions and services, are often considered separately in landscape planning. However, the potential synergies between them are currently poorly understood. Identifying the spatial patterns and factors driving their co‐occurrence across different climatic zones is critical to more effectively conserve forest ecosystems at the regional level. Here, we integrated information of National Forest Inventories and Breeding Bird Atlases across Europe and North America (Spain and Quebec, respectively), covering five subclimates (steppe, dry Mediterranean, humid Mediterranean, boreal, and temperate). In particular, this study aimed to (1) determine the spatial patterns of both forest carbon stocks and biodiversity (bird richness, tree richness, and overall biodiversity) and the factors that influence them; (2) establish the relationships between forest carbon stocks and biodiversity; and (3) define and characterize the areas of high (hotspots) and low (coldspots) values of carbon and biodiversity, and ultimately quantify their spatial overlap. Our results show that the factors affecting carbon and biodiversity vary between regions and subclimates. The highest values of carbon and biodiversity were found in northern Spain (humid Mediterranean subclimate) and southern Quebec (temperate subclimate) where there was more carbon as climate conditions were less limiting. High density and structural diversity simultaneously favored carbon stocks, tree, and overall biodiversity, especially in isolated and mountainous areas, often associated with steeper slopes and low accessibility. In addition, the relationship between carbon stocks and biodiversity was positive in both regions and all subclimates, being stronger where climate is a limiting factor for forest growth. The spatial overlap between hotspots of carbon and biodiversity provides an excellent opportunity for landscape planning to maintain carbon stocks and conserve biodiversity. The variables positively affecting carbon and biodiversity were also driving the hotspots of both carbon and biodiversity, emphasizing the viability of “win‐win” solutions. Our results highlight the need to jointly determine the spatial patterns of ecosystem services and biodiversity for an effective and sustainable planning of forest landscapes that simultaneously support conservation and mitigate climate change. [ABSTRACT FROM AUTHOR]

The choice of a rotation length is an integral part of even-aged forest management regimes. In this study, we simulated stand development and carbon pools in four even-aged stands representing the two most common tree species in Fennoscandia, Norway spruce ( Picea abies (L.) Karst.) and Scots pine ( Pinus sylvestris L.), growing on high- and low-productivity sites. We hypothesized that increased rotation lengths (+10, +20, and +30 years) in comparison with today's practice would increase forests' average carbon stock during a rotation cycle but decrease the average yield. The results showed that for spruce, a moderate increase in rotation length (+10 years) increased both average standing carbon stock and average yield. For the longer alternatives (+20 and +30 years) for spruce and for all pine alternatives, prolonging rotation lengths resulted in increased average standing carbon stocks but decreased average yield, resulting in decreased carbon storage in forest products and decreased substitution effects. Decreasing the rotation lengths (-10 years) always resulted in both decreased average standing carbon stocks and decreased yields. We conclude that a moderate increase of rotation lengths may slightly increase forests' climate benefits for spruce sites, but for all other alternatives, there was a trade-off between the temporary gain of increasing carbon stocks and the permanent loss in productivity and, consequently, substitution potential. [ABSTRACT FROM AUTHOR]

Key message: Inclusion of carbon nanoparticles in growth medium accelerates timing to flower by down-regulating phytochrome B in a CONSTANS-independent but photoperiod-dependent manner in Arabidopsis thaliana.Abstract: Despite the recognized importance of nanoparticles in plant development over the last decade, the effect of carbon nanoparticles (CNPs) on plant processes such as photomorphogenesis and flowering time control is poorly understood. We explored the uptake, accumulation and effect of CNPs on seedling development and flowering time control in Arabidopsis thaliana (At). CNPs uptake was demonstrated using Raman spectroscopy and light microscopy that affected At seedling growth and flowering time in a dose-dependent manner. The highest accumulation of CNPs was observed in leaves followed by stem and root tissues. CNPs treatment enhanced seed germination, showed elongated hypocotyl, larger cotyledon area and increased chlorophyll content in At seedlings. CNPs treatment induced early flowering in both long-day and short-day growth conditions indicating a photoperiod-dependent effect. CNPs-treated seedlings showed a drastic reduction in the relative abundance of phytochrome B (PHYB) transcript. Further, we analyzed the transcript abundance of at least one major component involved in various pathways that regulate flowering such as (1) photoperiod, (2) gibberellic acid (GA), (3) vernalization and (4) autonomous. An up-regulation of transcript levels of PHYTOCHROME INTERACTING FACTOR 4 (PIF4), GIGANTEA (GI), REPRESSOR OF GIBBERELLIC ACID 1 (RGA1) and LEAFY (LFY) were observed, however, there were no changes in the transcript levels of CONSTANS (CO), VERNALIZATION 1 (VRN1) and FLOWERING CONTROL LOCUS A (FCA). Despite the up-regulation of RGA1, we conclude that the earlier flowering is most likely GA-independent. Here, we demonstrated that the early flowering in CNPs-treated seedlings was PHYB and photoperiod-dependent. [ABSTRACT FROM AUTHOR]

We aimed at identifying which drivers control the spatio-temporal variability of fruit production in three major European temperate deciduous tree species: Quercus robur, Quercus petraea and Fagus sylvatica. We analysed the relations of fruit production with airborne pollen, carbon and water resources and meteorological data in 48 French forests over 14 years (1994-2007). In oak, acorn production was mainly related to temperature conditions during the pollen emission period, supporting the pollen synchrony hypothesis. In beech, a temperature signal over the two previous years eclipsed the airborne pollen load. Fruit production in Quercus and Fagus was related to climate drivers, carbon inputs and airborne pollen through strongly nonlinear, genus-specific relations. Quercus and Fagus also differed as regards the secondary growth versus fructification trade-off. While negative relationships were observed between secondary growth and fruit production in beech, more productive years benefited to both secondary growth and reproductive effort in oak. [ABSTRACT FROM AUTHOR]

The purpose of the study was to discover an effect of the composition on the basis of heterocyclic series containing derivatives of oxone FGSK-2,2 (dinitrophenylhydrazine 2,2-dimethyltetrahydropyran-4-one) with a concentration of 0.00001%, in different proportions with 20% raw carbon mineral on the growth and development of the spring wheat under laboratory conditions. The standard techniques of seeds' germination and plant culture were used in this study. Observations on germination, plant growth and thickness, as well as the photopigments' content were recorded. It was observed that plants in treatment with such composition grew up very well and contained a large amount of chlorophyll. Thus, it showed the rising productivity of plant culture. We observed a stimulating effect of the 20%-concentrated shungite on seed germination of spring wheat. The results of the study showed a decrease in linearity of a bark of the axial bodies and increase in a thickness of plant stems after treatment in a 1:1 ratio by means of the compositions of dinitrophenylhydrazine 2,2-dimethyltetrahydropyran-4-one and shungite. Furthermore, wheat leaves had the rich dark-green colour due to chlorophyll content in wheat plant leaves of all kinds of treatment that was higher in comparison with control plants. Plants in treatment by means of composition in a 2 : 1 ratio had the highest chlorophyll content. On the basis of these results, it was concluded that the treatment of spring wheat seeds by means of composition derived from oxone FGSK-2,2 (dinitrophenylhydrazone 2,2-dimethyltetrahydropyran-4-one) and 20%-concentrated shungite of 1 : 1, 2 : 1 and 1 : 2 ratios showed germination. The aqueous solution of shungite in the vegetative phase of wheat had an inhibitory effect on the plant height. There was found the stimulating effect of the composition of dinitrophenylhydrazone 2,2- dimethyltetrahydropyran-4-one and carbon mineral of 1 : 1, 2 : 1 and 1 : 2 ratios on the plant stem thickness. [ABSTRACT FROM AUTHOR]

Resource sharing is universal among connected ramets of clonal plants and is driven both by the developmental status of the ramets and the resource gradients. Above-ground competition forms spatial light gradients, but the role of resource sharing in such competition is unclear. We examined translocation of resources between mother and daughter ramets of Agrostis stolonifera under light heterogeneity throughout ramet ontogeny. We labelled ramets with 13C and 15N to estimate the bidirectional translocation of resources at three developmental stages of the daughters. In addition, we compared the final biomass of integrated and severed ramets in order to estimate the effect of integration on growth. Young developing daughters were supported by carbon, whereas nitrogen was only translocated towards daughters at the beginning of rooting, regardless of the light conditions. Shading of mothers was a major determinant of resource translocation between developed ramets, with carbon being preferentially moved to daughters from shaded mothers while nitrogen translocation was limited from daughters to shaded mothers. Surprisingly, the absolute amounts of translocated resources did not decline during development. Growth of daughters was enhanced by integration regardless of the shading. Overall, A. stolonifera maximizes the resource translocation pattern in order to enable it to spread from unfavourable habitats, rather than compensating for light heterogeneity among ramets. [ABSTRACT FROM AUTHOR]

Agroforestry systems (AFS) are considered large sinks of greenhouse gases (GHG) in the atmosphere. However, little is known about the dynamics of carbon accumulation in tree individuals over the years and the Age Thinning Technique (ATT) to potentialize GHG mitigation. The objective of the study was to predict the growth in carbon and determine the age thinning Technique of the tree component in 3 AFS in the municipality of Viçosa, MG, Brazil, in which System A is composed of eucalypt (Eucalyptus saligna) + pasture (Brachiaria decumbens) and systems B and C with eucalypt (Eucalyptus urophylla x Eucalyptus grandis) + pasture (Brachiaria decumbens). The Gompertz and Logistic models were employed to predict the timber volume and carbon growth. The ATT was determined based on the maximum productivity in timber volume per unit area. The curve asymptotic values of the systems A, B and C were 450, 221 and 226 m3 ha-1 for the volume and 104, 51 and 52 MgC ha-1 for the carbon, respectively. Stabilization of carbon accumulation will occur close to 100 months for systems A and B and at 80 months for system C. As the ATT ranged 64-80 months, the thinning is recommended before this age to promote the carbon accumulation of the remaining arboreal individuals. [ABSTRACT FROM AUTHOR]

In Arctic tundra, plant pathogens have substantial effects on the growth and survival of hosts, and impacts on the carbon balance at the scale of ecological systems. To understand these effects on carbon dynamics across different scales including plant organ, individual, population and ecosystem, we focused on two primary factors: host productivity reduction and carbon consumption by the pathogen. We measured the effect of the pathogen on photosynthetic and respiratory activity in the host. We also measured respiration and the amount of carbon in the pathogen. We constructed a model based on these two factors, and calculated pathogenic effects on the carbon balance at different organismal and ecological scales. We found that carbon was reduced in infected leaves by 118% compared with healthy leaves; the major factor causing this loss was pathogenic carbon consumption. The carbon balance at the population and ecosystem levels decreased by 35% and 20%, respectively, at an infection rate of 30%. This case study provides the first evidence that a host plant can lose more carbon through pathogenic carbon consumption than through a reduction in productivity. Such a pathogenic effect could greatly change ecosystem carbon cycling without decreasing annual productivity. [ABSTRACT FROM AUTHOR]

The effects of elevated ozone on C (carbon), N (nitrogen) and P (phosphorus) ecological stoichiometry and nutrient resorption in different organs including leaves, stems and roots were investigated in poplar clones 546 ( P. deltoides cv. ‘55/56’ × P. deltoides cv. ‘Imperial’) and 107 ( P. euramericana cv. ‘74/76’) with a different sensitivity to ozone. Plants were exposed to two ozone treatments, NF (non-filtered ambient air) and NF60 (NF with targeted ozone addition of 60 ppb), for 96 days in open top chambers (OTCs). Significant ozone effects on most variables of C, N and P ecological stoichiometry were found except for the C concentration and the N/P in different organs. Elevated ozone increased both N and P concentrations of individual organs while for C/N and C/P ratios a reduction was observed. On these variables, ozone had a greater effect for clone 546 than for clone 107. N concentrations of different leaf positions ranked in the order upper > middle > lower, showing that N was transferred from the lower senescent leaves to the upper ones. This was also indicative of N resorption processes, which increased under elevated ozone. N resorption of clone 546 was 4 times larger than that of clone 107 under ambient air (NF). However, elevated ozone (NF60) had no significant effect on P resorption for both poplar clones, suggesting that their growth was only limited by N, while available P in the soil was enough to sustain growth. Understanding ecological stoichiometric responses under ozone stress is crucial to predict future effects on ecological processes and biogeochemical cycles. [ABSTRACT FROM AUTHOR]

Strobilurins are fungicides with beneficial physiological effects on crop yield due to promotion of net carbon assimilation, nitrate reductase enzyme activity, stress tolerance and hormonal balance. The carboxamides complement the action of the strobilurins when applied alternately or together. This study aimed to evaluate the effect of application of pyraclostrobin, azoxystrobin and boscalid on grafted and ungrafted Japanese cucumber ( Cucumis sativus L.) in order to analyze the effects of these fungicides on plant physiology and increased fruit production. The experimental design was completely randomized in a 2 × 5 factorial scheme, with grafted and ungrafted cucumber plants and 5 fungicide treatments: control; azoxystrobin 60 g a.i ha −1 ; boscalid 50 g a.i ha −1 ; pyraclostrobin 50 g a.i ha −1 ; and boscalid 100 g a.i ha −1 + pyraclostrobin 50 g a.i ha −1 , applied 18 days after transplanting and then at intervals of seven days. The effect of the treatments was evaluated based on the average yield and fruit mass, in addition to observations of gas exchange, lipid peroxidation, and the activities of peroxidase, superoxide dismutase, catalase and nitrate reductase. Based on the results obtained, it was concluded that the fungicide treatments resulted in different responses between the grafted and ungrafted plants. The physiological benefits were more evident in the grafted plants treated with pyraclostrobin or boscalid alone, and these benefits manifested in terms of fruit production and increased the activity of the antioxidative system, thereby reducing stress. The higher productivity probably occurred due to the better physiological performance of these plants, mainly at the beginning of development, presenting greater activity of the enzyme nitrate reductase, in addition to the higher net CO 2 assimilation and carboxylation efficiency. [ABSTRACT FROM AUTHOR]

Morphology, physical and chemical properties of carbonaceous materials (CMs) synthesized by hydrothermal carbonization (HTC) of a technical lignin, HP-L™, derived from a bio-refinery waste-stream is reported. The technical lignin, HP-L™, was hydrothermally carbonized at four processing temperatures; 200, 250, 300 and 350 °C. The yield of derived CMs was highest at the lowest processing temperature (200 °C), and decreased with increasing temperature. L350, obtained at 350 °C was further chemically activated with KOH. SEM analysis showed that lignin exhibited agglomerated structures with some vesicles at elevated temperatures. Overall, major structural changes in the HP-L™ lignin only occurred after 300 °C. Vibrational spectroscopy showed bands due to lignin functionalities disappeared at 350 °C. This was supported by deconvolution and peak analysis using NMR, which revealed the evolution of a more condensed structure characterized by aromatic C when temperature reached 350 °C. Unlike carbohydrates and other biomass types which can easily be hydrothermally carbonized at temperatures (160–220 °C), HP-L™ lignin remains relatively unchanged up until 350 °C where significant aromatization occurs. 350 °C is therefore the desired temperature for the hydrothermal treatment of HP-L™ lignin. [ABSTRACT FROM AUTHOR]

As aboveground biomass of perennial grasses is harvested for feedstock or bioenergy production, root biomass C and N become primary C and N inputs for enhancing soil C and N sequestration. Information is scanty about root biomass C and N and subsequent soil C and N stocks under bioenergy perennial grasses applied with various N fertilization rates in semiarid regions. We evaluated the effect of perennial grass species and N rates on root biomass C and N and soil total C (STC) and total N (STN) stocks at the 0–120 cm depth from 2011 to 2013, 2–4 yr after grass establishment, in the northern Great Plains, USA. Perennial grasses were intermediate wheatgrass ( Thinopyrum intermedium [Host] Barkworth and Dewey), smooth bromegrass ( Bromus inermis L.), and switchgrass ( Panicum virgatum L.), and N fertilization rates were 0, 28, 56, and 84 kg N ha −1 . Root biomass C and N at 0–15 and 0–120 cm were greater with intermediate wheatgrass and switchgrass than smooth bromegrass in 2011, but the trend reversed for root biomass C at 0–15 cm in 2012. Root biomass C at both depths among N rates and years. The STC at 0–15, 30–60, and 0–120 cm also varied among grass species and years. At 30–60 cm, STC increased with increased N rates under intermediate wheatgrass and switchgrass, but decreased under smooth bromegrass. At 60–90 cm, the trend for STC reversed. The STN at 15–30 cm was greater under intermediate wheatgrass than smooth bromegrass and switchgrass and at most depths was greater in 2012 than 2013. Overall root biomass C and N at 0–120 cm were 12–16 times greater and STC and STN 8–9% greater under perennial grasses than adjacent annual spring wheat. Although intermediate wheatgrass returned more root C and N to the soil than other grasses, both STC and STN varied among grass species and N rates. Increased root C and N inputs, however, increased STC and STN under perennial grasses compared with annual spring wheat. [ABSTRACT FROM AUTHOR]

Background: Differences in cropping systems and their impacts on plant growth and carbon (C) uptake as well as soil C release pose a major challenge in projecting agroecosystem C balance. Methods: A four-year (2012-2015) field experiment was conducted to examine crop C uptake and soil respiration in two conventional (wheat-cotton and wheat-maize) and two legume-based (wheat-soybean and alfalfa-maize) double-season cropping systems in North China Plain. Results: During the 4 experimental years, crop C uptake was greater in the two conventional systems than the two legume-based systems. However, soil respiration was higher in the two systems with C (i.e. maize) than C crops (i.e. cotton and soybean) planted in summer. As consequences, cropland C balance was positive in the two conventional cropping systems, with greater value in the wheat-maize comparing to wheat-cotton system. However, the two legume-based cropping systems showed negative cropland C balance. Conclusions: Our findings indicate that, although more CO-C is emitted in maize-related cropping systems, the conventional agricultural activities may sequestrate more C in comparison with the legume-based farming in North China Plain due to higher C uptake, and highlight the importance of management strategy in improving agroecosystem C storage. [ABSTRACT FROM AUTHOR]

Carbon and nitrogen metabolism are regulated by complex mechanisms in order to optimize growth and development of plants and play a major role during germination and postgerminative growth. The objective of the current work was to establish the degree of changes in activities of key enzymes implicated in these two metabolism pathways during germination and post-germinative growth such as; glutamine synthetase, glutamate dehydrogenase, phosphoenolpyruvate carboxylase, malate dehydrogenase, isocitrate dehydrogenase and aspartate aminotransferase. We have observed that during germination and seedlings development the most activities of nitrogen and carbon metabolism enzymes were correlated (nearly show similar kinetic changes) and influenced by their cellular environment and developmental stage. Therefore, higher activities of these enzymes were observed in the seed, root and shoot at early stages of the post-germinative phase could be effectively linked to the demand of de novo proteins to ensure a good development of seedlings. [ABSTRACT FROM AUTHOR]

This study was developed to evaluate the effects of salinity on the growth and gas exchange of cassava plants, cultivar Verdinha. The four concentrations of NaCl (mM) were as follows: 0, 20, 40, and 60. Under salinity, the lowest concentration of Na+ ions was observed in the tuberous roots; however, the dry matter of tuberous roots was reduced with an application of just 20 mM NaCl. The harvest index was reduced 50% with the highest salt concentration. Salinity reduced carbon assimilation (A), stomatal conductance (gs), transpiration, and the instantaneous water use efficiency. The correlation between gs and A was high and positive, showing that stomatal movement was one of the responsible for the lower A. Under salt stress, there was an increase in intercellular CO2 concentration, indicating the impairment of carbon metabolism. Based on the reduction of dry matter of the tuberous roots (reduction of 81% under 60 mM NaCl), it was concluded that cassava is sensitive to salinity. The growth of shoots and the absorbing roots were minimally affected by salinity, even in the situation where A was reduced; therefore, the sensitivity of cassava was related to the high sensitivity of the tuberous roots to the ionic and/or osmotic effects of salinity. Thus, tuberous roots can be the target organ in studies that aim to improve the tolerance of cassava to salinity. [ABSTRACT FROM AUTHOR]

Background and Aims An understanding of spatial variation in soil respiration is critical to determining the carbon balance in grapevines. The effect of soil water content on soil respiration during different phenological stages in two grapevine cultivars, Grenache and Tempranillo, was studied over two seasons (2013 and 2014). Methods and Results Soil respiration was measured from five locations confined to within and between rows of vines at five phenological stages between budburst and postharvest under irrigated and non-irrigated conditions. Vine phenology influenced the in-row soil CO2 efflux to a greater extent than the between-row CO2 efflux, while irrigation resulted in in-row soil respiration 65% higher than that of the between-row positions. In contrast, the flux from the in-row positions of the non-irrigated treatment was only 25% higher than that of the between-row positions. Soil moisture and vine phenological stages appeared to have a greater influence on soil respiration than soil temperature. Conclusions Significant correlations existed among soil respiration, irrigation and the vine phenological stages. Soil respiration increased from budburst to pea-size berry stage; thereafter, it decreased until the ripening stage before increasing again during the postharvest stage. Significance of the Study The study showed that soil water availability and vine phenology play an important role in influencing soil respiration under field conditions. [ABSTRACT FROM AUTHOR]

The potential of untreated Parthenium hysterophorus weed biomass was evaluated as a substrate for cellulase production. The cellulose in the biomass was used as the main source of carbon. Solid-state fermentation was carried out using Trichoderma reesei, and optimization of cultural conditions was done for maximization of cellulase production. The results revealed that highest cellulase production was achieved on the 8th day of incubation, at 30 °C, keeping solid-to-liquid ratio 1:2 when two discs of inoculum were used per gram of the substrate. The optimized inoculum age was 96 h for CMCase and 120 h for FPase. On studying the enhancing effect of different carbon and nitrogen sources, lactose and ammonium molybdate were found suitable, respectively. The optimized concentration of lactose for the highest CMCase and FPase activities was 1.5 and 1%, respectively. Ammonium molybdate was best at 1% concentration for both CMCase and FPase. Maximum CMCase and FPase activities obtained were 20.49 and 2.42 U/gds, respectively. [ABSTRACT FROM AUTHOR]

Under nutrient deplete conditions, diatoms accumulate between 15% to 25% of their dry weight as lipids, primarily as triacylglycerols ( TAGs). As in most eukaryotes, these organisms produce TAGs via the acyl-CoA dependent Kennedy pathway. The last step in this pathway is catalyzed by diacylglycerol acyltransferase ( DGAT) that acylates diacylglycerol ( DAG) to produce TAG. To test our hypothesis that DGAT plays a major role in controlling the flux of carbon towards lipids, we overexpressed a specific type II DGAT gene, DGAT2D, in the model diatom Phaeodactylum tricornutum. The transformants had 50- to 100-fold higher DGAT2D mRNA levels and the abundance of the enzyme increased 30- to 50-fold. More important, these cells had a 2-fold higher total lipid content and incorporated carbon into lipids more efficiently than the wild type ( WT) while growing only 15% slower at light saturation. Based on a flux analysis using 13C as a tracer, we found that the increase in lipids was achieved via increased fluxes through pyruvate and acetyl-CoA. Our results reveal overexpression of DAGT2D increases the flux of photosynthetically fixed carbon towards lipids, and leads to a higher lipid content than exponentially grown WT cells. [ABSTRACT FROM AUTHOR]

Post-silking nitrogen (N) fluxes from vegetative tissues to developing kernels affect both N use efficiency (NUE) and grain yield in maize, while the impacts of various N applications at and especially after silking on temporal dynamics of post-silking N uptake and remobilization are poorly understood. Field experiments were conducted with N regimes ranging from low to high N levels. Nitrogen applications above optimal rates at and after silking neither increased late-season N uptake and leaf photosynthesis, nor reduced leaf N export during grain filling compared to the optimal N input, and thus significantly reduced the NUE. In most experiments, reductions in leaf N concentrations were observed around 15 days after silking (DAS). A 15 N labeling study revealed that remobilization of N taken up prior to silking from vegetative tissues during the entire grain-filling phase was 58%–60%, which contributed 53%–61% of the total grain N at maturity, and more than 60% of it was remobilized during the 0–30 DAS. N remobilization initially occurred preferentially from stems relative to leaves, while significant amounts of N were remobilized from leaves during late grain filling and deposited in the stem, particularly in high N treatments. No matter whether 15 N was applied before or at silking, a greater proportion of 15 N taken up was allocated to leaves under N deficient than under N sufficient conditions. At maturity, 70%–76% of the N taken up after silking was allocated to grain. Under N deficiency, direct N allocation to grains originating from post-silking uptake was 45%, 56%, 70% and 96% at 0–15, 15–30, 30–46 and 46–60 DAS, respectively, while these values were relatively lower and constant in N-sufficient plants (43%–50%). Overall, results indicated a strong developmental control over post-silking N fluxes with limited differences observed between N deficient and N sufficient maize, but no impact of high N applications to N-sufficient plants at or after silking. [ABSTRACT FROM AUTHOR]

This article is a Commentary on Huang et al., 222: 144–158. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the combined effect of fogging and cold plate refrigeration on white asparagus quality during storage on a vegetable stall. Of the three storage conditions (Control, C; Fog, F; and Fog-Cold plate, FC), FC ensured that white asparagus retained a fresher appearance and had a longer shelf life (at least 5 d). Weight loss was reduced in products stored under FC conditions; meanwhile, weight loss was up to 14% when asparagus were stored under C conditions for 3 d. In the case of asparagus stored under F and C, browning was observed and the visual appearance of the product deteriorated obviously after 1 d, whereas for products stored under FC, such deterioration occurred only after 3 d or more. The results demonstrated that FC could be a promising technique for white asparagus storage on vegetable stalls. [ABSTRACT FROM AUTHOR]

The focus on forest carbon estimation accompanying the implementation of increased regulatory and reporting requirements is fostering the development of numerous tools and methods to facilitate carbon estimation. One such well-established mechanism is via the Forest Vegetation Simulator (FVS), a growth and yield modeling system used by public and private land managers and researchers, which provides two alternate approaches to quantifying carbon in live trees on forest land – these are known as the Jenkins and Fire and Fuels Extension (FFE) equations. A necessary consideration in developing forest carbon estimates is to address alternate, potentially different, estimates that are likely available from more than one source. A key to using such information is some understanding of where alternate estimates are expected to produce equivalent results. We address this here by focusing on potential equivalence among three commonly employed approaches to estimating individual-tree carbon, which are all applicable to inventory sampling or inventory simulation applications. Specifically, the two approaches available in FVS – Jenkins and FFE – and the third, the component ratio method (CRM) used in the U.S. Forest Service’s, Forest Inventory and Analysis national DataBase (FIADB). A key finding of this study is that the Jenkins, FFE, and CRM methods are not universally equivalent, and that equivalence varies across regions, forest types, and levels of data aggregation. No consistent alignment of approaches was identified. In general, equivalence was identified in a greater proportion of cases when forests were summarized at more aggregate levels such as all softwood type groups or entire variants. Most frequently, the FIA inventory-based CRM and FFE were determined to be equivalent. [ABSTRACT FROM AUTHOR]

The rapid loss of eastern hemlock ( Tsuga canadensis ) due to infestation with hemlock woolly adelgid ( Adelges tsugae , HWA) has greatly altered structure and function of eastern forests. Numerous control strategies including local pesticide use and biocontrol with predator beetles have been implemented with considerable cost and varying success. Silviculture treatments that increase incident light on surviving hemlock trees to reduce infestation and ameliorate carbon starvation have been proposed as another possible conservation strategy, yet no controlled studies have evaluated the coupled plant-insect responses to increased light. We conducted a nursery experiment on artificially infested eastern hemlock seedlings under varying levels of ambient light, ranging from 0 to 90% shade. We measured HWA infestation (ovisac density), short- and long-term indicators of carbon balance (leaf chlorophyll fluorescence, net photosynthesis, total nonstructural carbohydrate content, and shoot growth), and nutrition (leaf N content). We hypothesized that higher light would result in reduced HWA densities, higher C assimilation rates, and improved tissue non-structural carbohydrate balance; and these effects would ameliorate the effects of infestation on C balance and lead to improved seedling growth. HWA density decreased with increasing light, and was highest in the 90% shade treatments. However, photosystem II efficiency and net assimilation were also lower under the higher light treatment. Despite tradeoffs between reduced infestation and reduced leaf function from higher light, and little variation in sugar content among treatments, both leaf and root starch content and seedling growth were higher under the higher light treatment. Increasing light levels improves long-term carbon balance for hemlock seedlings in the presence of HWA. Although hemlock typically occurs in deeply shaded forests, our results suggest that silvicultural treatments such as forest thinning that increase light exposure may reduce HWA abundance and lead to better tree C balance, and may be an effective component of large-scale conservation and restoration strategies. [ABSTRACT FROM AUTHOR]

The internal C:N balance must be tightly controlled for the normal growth and development of plants. However, the underlying mechanisms, by which plants sense and balance the intracellular C:N status correspondingly to exogenous C:N availabilities remain elusive. In this study, we use comparative gene expression analysis to identify genes that are responsive to imbalanced C:N treatments in the aerial parts of rice seedlings. Transcripts of rice seedlings treated with four C:N availabilities (1:1, 1:60, 60:1 and 60:60) were compared and two groups of genes were classified: high C:low N responsive genes and low C:high N responsive genes. Our analysis identified several functional correlated genes including chalcone synthase (CHS), chlorophyll a-b binding protein (CAB) and other genes that are implicated in C:N balancing mechanism, such as alternative oxidase 1B (OsAOX1B), malate dehydrogenase (OsMDH) and lysine and histidine specific transporter 1 (OsLHT1). Additionally, six jasmonate synthetic genes and key regulatory genes involved in abiotic and biotic stresses, such as OsMYB4, autoinhibited calcium ATPase 3 (OsACA3) and pleiotropic drug resistance 9 (OsPDR9), were differentially expressed under high C:low N treatment. Gene ontology analysis showed that high C:low N up-regulated genes were primarily enriched in fatty acid biosynthesis and defense responses. Coexpression network analysis of these genes identified eight jasmonate ZIM domain protein (OsJAZ) genes and several defense response related regulators, suggesting that high C:low N status may act as a stress condition, which induces defense responses mediated by jasmonate signaling pathway. Our transcriptome analysis shed new light on the C:N balancing mechanisms and revealed several important regulators of C:N status in rice seedlings. [ABSTRACT FROM AUTHOR]

The contribution of new photo-assimilates and stored carbon (C) to plant growth remains poorly understood, especially during reproduction. In order to elucidate how mast seeding affects C allocation to both reproductive and vegetative tissues, we measured biomass increase in each tissue, branch starch concentration and stable C isotope composition (δ13C) in bulk leaves, current-year shoots, 3-year branches and tree rings in fruiting and non-fruiting trees for 2 years, as well as in fruits. We isolated the effect of reproduction on C allocation to vegetative growth by comparing 13C enrichment in woody tissues in fruiting and nonfruiting specimens. Compared with 2‰ 13C enrichment in shoots relative to leaves from non-fruiting trees, fruiting reduced the enrichment to 1‰ and this reduction disappeared in the following year with no fruiting, indicating that new photo-assimilates are preferentially used for woody tissues even with fruiting burden. In contrast, fruits had up to 2.5‰ 13C enrichment at midsummer, which dropped thereafter, indicating that fruit production relies on C storage early in the growing season then shifts to current photo-assimilates. At this tipping point, growth of shoots and cupules had almost finished and nuts had a second rapid growth period thereafter. Together with shorter shoots but higher biomass increment per length in fruiting trees than nonfruiting trees, these results indicate that the C limitation due to fruit burden is minimized by fine-tuning of allocation of old C stores and new photo-assimilates, along with the growth pattern in various tissues. Furthermore, fruiting had no significant effect on starch concentration in 3-year-old branches, which became fully depleted during leaf and flower flushing but were quickly replenished. These results indicate that reproduction affects C allocation to branches but not its source or storage. These reproduction-related variations in the fate of C have implications for evaluating forest ecosystem C cycles during climate change. [ABSTRACT FROM AUTHOR]

Microbial communities associated with a plant host, constituting a holobiont, affect the physiology and growth of the plant via metabolites that are mainly derived from their photosynthates. The structure and function of active microbial communities that assimilate root exudates can be tracked by using stable isotope probing (SIP) approaches. This article reviews results from ongoing SIP research in plant–microbe interactions, with a specific focus on investigating the fate of fresh and recalcitrant carbon in the rhizosphere with 13 C enriched-root exudates, in addition to identifying key players in carbon cycling. Finally, we discuss new SIP applications that have the potential to identify novel enzymes implicated in rhizoremediation or plant genes dedicated to root exudation by combining SIP approaches and genome wide associations studies. [ABSTRACT FROM AUTHOR]

Recent reports on tree mortality associated with anomalous drought and heat have raised interest into processes underlying tree resistance/resilience to water stress. Hydraulic failure and carbon starvation have been proposed as main causes of tree decline, with recent theories treating water and carbon metabolism as interconnected processes. We subjected young plants of two native ( Quercus pubescens [Qp] and Prunus mahaleb [Pm]) and two invasive ( Robinia pseudoacacia [Rp] and Ailanthus altissima [Aa]) woody angiosperms to a prolonged drought leading to stomatal closure and xylem embolism, to induce carbon starvation and hydraulic failure. At the end of the treatment, plants were measured for embolism rates and NSC content, and re-irrigated to monitor recovery of xylem hydraulics. Data highlight different hydraulic strategies in native vs invasive species under water stress, and provide physiological explanations for species-specific impacts of recent severe droughts. Drought-sensitive species (Qp and Rp) suffered high embolism rates and were unable to completely refill xylem conduits upon restoration of water availability. Species that better survived recent droughts were able to limit embolism build-up (Pm) or efficiently restored hydraulic functionality after irrigation (Aa). Species-specific capacity to reverse xylem embolism correlated to stem-level concentration of soluble carbohydrates, but not to starch content. [ABSTRACT FROM AUTHOR]

Postharvest pathogens can penetrate fruit by breaching the cuticle or directly through wounds, and they show disease symptoms only long after infection. During ripening and senescence, the fruit undergo physiological processes accompanied by a decline in antifungal compounds, which allows the pathogen to activate a mechanism of secretion of small effector molecules that modulate host environmental pH. These result in the activation of genes under their optimal pH conditions, enabling the fungus to use a specific group of pathogenicity factors at each particular pH. New research suggests that carbon availability in the environment is a key factor triggering the production and secretion of small pH-modulating molecules: ammonia and organic acids. Ammonia is secreted under limited carbon and gluconic acid under excess carbon. This mini review describes our most recent knowledge of the mechanism of activation of pH-secreted molecules and their contribution to colonization by postharvest pathogens to facilitate the transition from quiescence to necrotrophic lifestyle. [ABSTRACT FROM AUTHOR]

In plants, the partitioning of carbon resources between growth and defense is detrimental for their development. From a metabolic viewpoint, growth is mainly related to primary metabolism including protein, amino acid and lipid synthesis, whereas defense is based notably on the biosynthesis of a myriad of secondary metabolites. Environmental factors, such as nitrate fertilization, impact the partitioning of carbon resources between growth and defense. Indeed, experimental data showed that a shortage in the nitrate fertilization resulted in a reduction of the plant growth, whereas some secondary metabolites involved in plant defense, such as phenolic compounds, accumulated. Interestingly, sucrose, a key molecule involved in the transport and partitioning of carbon resources, appeared to be under homeostatic control. Based on the inflow/outflow properties of sucrose homeostatic regulation we propose a global model on how the diversion of the primary carbon flux into the secondary phenolic pathways occurs at low nitrate concentrations. The model can account for the accumulation of starch during the light phase and the sucrose remobilization by starch degradation during the night. Day-length sensing mechanisms for variable light–dark regimes are discussed, showing that growth is proportional to the length of the light phase. The model can describe the complete starch consumption during the night for plants adapted to a certain light/dark regime when grown on sufficient nitrate and can account for an increased accumulation of starch observed under nitrate limitation. [ABSTRACT FROM AUTHOR]

Carbon (C) and nitrogen (N) are two essential elements that influence plant growth and development. The C and N metabolic pathways influence each other to affect gene expression, but little is known about which genes are regulated by interaction between C and N or the mechanisms by which the pathways interact. In the present investigation, proteome analysis of N-efficient and N-inefficient Indian mustard, grown under varied combinations of low-N, sufficient-N, ambient [CO2], and elevated [CO2] was carried out to identify proteins and the encoding genes of the interactions between C and N. Two-dimensional gel electrophoresis (2-DE) revealed 158 candidate protein spots. Among these, 72 spots were identified by matrix-assisted laser desorption ionization-time of flight/time of flight mass spectrometry (MALDI-TOF/TOF). The identified proteins are related to various molecular processes including photosynthesis, energy metabolism, protein synthesis, transport and degradation, signal transduction, nitrogen metabolism and defense to oxidative, water and heat stresses. Identification of proteins like PII-like protein, cyclophilin, elongation factor-TU, oxygen-evolving enhancer protein and rubisco activase offers a peculiar overview of changes elicited by elevated [CO2], providing clues about how N-efficient cultivar of Indian mustard adapt to low N supply under elevated [CO2] conditions. This study provides new insights and novel information for a better understanding of adaptive responses to elevated [CO2] under N deficiency in Indian mustard. [ABSTRACT FROM AUTHOR]

A combined increase in seawater [CO2] and [H+] was recently shown to induce a shift from photosynthetic HCO3− to CO2 uptake in Emiliania huxleyi. This shift occurred within minutes, whereas acclimation to ocean acidification (OA) did not affect the carbon source., To identify the driver of this shift, we exposed low- and high-light acclimated E. huxleyi to a matrix of two levels of dissolved inorganic carbon (1400, 2800 μmol kg−1) and pH (8.15, 7.85) and directly measured cellular O2, CO2 and HCO3− fluxes under these conditions., Exposure to increased [CO2] had little effect on the photosynthetic fluxes, whereas increased [H+] led to a significant decline in HCO3− uptake. Low-light acclimated cells overcompensated for the inhibition of HCO3− uptake by increasing CO2 uptake. High-light acclimated cells, relying on higher proportions of HCO3− uptake, could not increase CO2 uptake and photosynthetic O2 evolution consequently became carbon-limited., These regulations indicate that OA responses in photosynthesis are caused by [H+] rather than by [CO2]. The impaired HCO3− uptake also provides a mechanistic explanation for lowered calcification under OA. Moreover, it explains the OA-dependent decrease in photosynthesis observed in high-light grown phytoplankton. [ABSTRACT FROM AUTHOR]

Mitigation of climate change via increased plant productivity and soil carbon (C) sequestration during land use change can be a powerful driver of the net greenhouse gas emissions of a sustainable production system. Yet the net climate change mitigation of managed forests is affected by both tradeoffs between C sequestration and non-renewable C emissions and assessment methodology. As a case study, we measured ecosystem stocks to determine the potential C implications of converting pasture to managed eucalyptus forest and compared them with the eucalyptus production system's non-renewable C emissions. The forest border was chosen as the system boundary and operations spanned from forest establishment activities to harvested wood placed at the forest perimeter. Eucalyptus biomass C was 57.2 ± 4.2 Mg C ha−1and soil C stock (to ∼1 m depth) was approximately an order of magnitude greater. By the prevalent method for bulk density-based determination of C stock, conversion of pasture to eucalyptus forest significantly increased soil C stock by 17.5 ± 8.0%. However, no significant change was detected by the equivalent soil mass method, a less prevalent but more accurate approach to detecting differences in soil C stock due to land use or management changes. A 7-year eucalyptus production cycle generated 1.0 Mg C ha−1in non-renewable emissions, which was far exceeded by the tree biomass C. Thus, even without significant soil C sequestration, this system provided a substantial climate change mitigation service by offsetting non-renewable energy use and C emissions associated with wood production, and providing opportunities for biofuel and bioenergy products to displace fossil fuel products. [ABSTRACT FROM AUTHOR]

Photosynthetically derived rhizodeposits are an important source of carbon (C) for microbes in root vicinity and can influence the microbial community dynamics. Pulse labeling of carbon dioxide (13CO2) coupled with stable isotope probing techniques have potential to track recently fixed photosynthate into rhizosphere microbial taxa. Therefore, the present investigation assessed the microbial community change associated with the rhizosphere and bulk soil inJatropha curcasL. (a biofuel crop) by combining phospholipid fatty acid (13C-PLFA) profiling using a stable isotope13CO2labeling approach. The labeling (13C) took place after 45 days of germination, PLFAs were extracted from both soils (rhizosphere and bulk) after 1 and 20 days pulse labeling and analyzed by gas chromatography-isotope ratio mass spectrometry. There was no significant temporal effect on the PLFA profiles in the bulk soil, but significantly increased abundance of Gram positive (i15:0) and Gram negative (16:1ω7c and 16:1ω5c) biomarkers was observed in the rhizosphere soil from day 1 to day 20 after labeling. The Gram negative (16:1ω7c) decreased and fungal (18:2ω6,9c) increased significantly in rhizospheric soil compared to bulk soil after day 1 of labeling. Whereas, after 20 days of labeling, the Gram negative biomarker (16:1ω7c and 18:1ω7c) decreased and Gram positive (a15:0) increased significantly in rhizospheric soil compared to bulk soil. One day following labeling, i15:0, a15:0, i16:0, 16:1ω5c, 16:0, i17:0, a17:0, 18:2ω6,9c, 18:1ω9c, and 18:0 PLFAs were significantly more enriched in δ13C in the rhizosphere than in the bulk soil. Twenty days after labeling, 16:1ω5c (Gram negative) and 18:2ω6,9c (fungal) were significantly more enriched in δ13C in the rhizosphere than in the bulk soil. These results shows the effectives of PLFA coupled using the pulse chase labeling technique to examine the microbial community changes in response to recently fixed photosynthetic C flow in rhizodeposits. [ABSTRACT FROM AUTHOR]

We attempted to enhance the growth and total lipid production of three microalgal species, Isochrysis galbana LB987, Nannochloropsis oculata CCAP849/1, and Dunaliella salina, which are capable of accumulating high content of lipid in cells. Low nitrogen concentration under photoautotrophic conditions stimulated total lipid production, but a decreasing total lipid content and an increasing biomass were observed with increasing nitrogen concentration. Among the different carbon sources tested for heterotrophic cultivation, glucose improved the growth of all three strains. The optimal glucose concentration for growth of I. galbana LB987 and N. oculata CCAP849/1 was 0.02 M, and that of D. salina was 0.05 M. Enhanced growth occurred when they were cultivated under heterotrophic or mixotrophic conditions compared with photoautotrophic conditions. Meanwhile, high total lipid accumulation in cells occurred when they were cultivated under photoautotrophic or mixotrophic conditions. During mixotrophic cultivation, biomass production was not affected significantly by light intensity; however, both chlorophyll concentration and total lipid content increased dramatically with increasing light intensity up to 150 µmol/m/s. The amount and composition ratio of saturated and unsaturated fatty acids in cells were different from each other depending on both species and light intensity. The highest accumulation of total fatty acid (C16-C18) among the three strains was found from cells of N. oculata CCAP849/1, which indicates that this species can be used as a source for production of biodiesel. [ABSTRACT FROM AUTHOR]

We lack both a theoretical framework and solid empirical data to understand domestication impacts on plant chemistry. We hypothesised that domestication increased leaf N and P to support high plant production rates, but biogeographic and climate patterns further influenced the magnitude and direction of changes in specific aspects of chemistry and stoichiometry. To test these hypotheses, we used a data set of leaf C, N and P from 21 herbaceous crops and their wild progenitors. Domestication increased leaf N and/or P for 57% of the crops. Moreover, the latitude of the domestication sites (negatively related to temperature) modulated the domestication effects on P (+), C (−), N : P (−) and C : P (−) ratios. Further results from a litter decomposition assay showed that domestication effects on litter chemistry affected the availability of soil N and P. Our findings draw attention to evolutionary effects of domestication legacies on plant and soil stoichiometry and related ecosystem services (e.g. plant yield and soil fertility). [ABSTRACT FROM AUTHOR]

This paper updates previous assessments of important environmental impacts associated with using crop biotechnology in global agriculture. It focuses on the environmental impacts associated with changes in pesticide use and greenhouse gas emissions arising from the use of GM crops since their first widespread commercial use in the mid 1990s. The adoption of GM insect resistant and herbicide tolerant technology has reduced pesticide spraying by 581.4 million kg (−8.2%) and, as a result, decreased the environmental impact associated with herbicide and insecticide use on these crops (as measured by the indicator, the Environmental Impact Quotient [EIQ]) by18.5%. The technology has also facilitated important cuts in fuel use and tillage changes, resulting in a significant reduction in the release of greenhouse gas emissions from the GM cropping area. In 2014, this was equivalent to removing nearly 10 million cars from the roads. [ABSTRACT FROM AUTHOR]

Understanding the effects of elevated atmospheric CO 2 on carbon (C) relations of mature forest trees is central to understanding ecosystem C fluxes and pools in a future high-CO 2 world. Here, we investigated the CO 2 -induced photosynthetic enhancement and the diurnal variation in shoot carbon assimilation, stem CO 2 efflux and soil respiration associated with ca. 110-year-old and 37 m tall Norway spruce trees ( Picea abies (L.) H. Karst.) growing under free air CO 2 enrichment (FACE) in a mixed, near-natural forest in Northern Switzerland. Diurnal measurements of these major C fluxes were conducted simultaneously on three occasions: one week before and after the start of CO 2 enrichment, and one year later. Under controlled leaf chamber conditions, an increase in the atmospheric CO 2 concentration of ca. 150 ppm above ambient stimulated light-saturated rates of photosynthesis in previous- and current-year upper-canopy shoots equally by 73 ± 2%. In the course of the day such large differences in C assimilation between trees growing under elevated CO 2 ( e CO 2 ) and ambient conditions ( a CO 2 ) only occurred around midday under non-limiting light conditions. The CO 2 efflux rates from spruce stems ( CE stem ) and surrounding soil ( R soil ) shared a similar range during night- and daytime (3–5 μmol m −2 s −1 ) but were not stimulated by e CO 2 . Both CE stem stem and R soil were still rising when photosynthesis approached evening light compensation potentially reflecting the time lag in assimilate allocation to stem tissue and fine roots. Our findings suggest a strong photosynthetic enhancement during the initial CO 2 enrichment phase but provide no evidence for an overall or daytime-dependent stimulation of respiratory CO 2 fluxes indicating that the extra C was not quickly returned to the atmosphere through respiratory processes in spruce stems or surrounding soil. [ABSTRACT FROM AUTHOR]

The competitive equilibrium between deciduous and evergreen plant species to a large extent depends on the intensity of the reduction in carbon gain undergone by evergreen leaves, associated with the leaf traits that confer resistance to stressful conditions during the unfavourable part of the year. This study explores the effects of winter harshness on the resistance traits of evergreen leaves. Leaf mass per unit area (LMA), leaf thickness and the concentrations of fibre, nitrogen (N), phosphorus (P), soluble protein, chlorophyll and ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) were determined in three evergreen and two deciduous species along a winter temperature gradient. In the evergreen species, LMA, thickness, and P and structural carbohydrate concentrations increased with the decrease in winter temperatures. Nitrogen and lignin concentrations did not show definite patterns in this regard. Chlorophyll, soluble proteins and Rubisco decreased with the increase in winter harshness. Our results suggest that an increase in LMA and in the concentration of structural carbohydrates would be a requirement for the leaves to cope with low winter temperatures. The evergreen habit would be associated with higher costs at cooler sites, because the cold resistance traits imply additional maintenance costs and reduced N allocation to the photosynthetic machinery, associated with structural reinforcement at colder sites. [ABSTRACT FROM AUTHOR]

In the rhizosphere, the uptake of low molecular weight carbon (C) and nitrogen (N) by plant roots has been well documented. While organic N uptake relatively to total uptake is important, organic C uptake is supposed to be low relatively to the plant's C budget. Recently, radiocarbon analyses demonstrated that a fraction of C from the soil was occluded in amorphous silica micrometric particles that precipitate in plant cells (phytoliths). Here, we investigated whether and in which extent organic C absorbed by grass roots, under the form of either intact amino acids (AAs) or microbial metabolites, can feed the organic C occluded in phytoliths. For this purpose we added 13C- and 15N-labeled AAs to the silicon-rich hydroponic solution of the grass Festuca arundinacea. The experiment was designed to prevent C leakage from the labeled nutritive solution to the chamber atmosphere. After 14 days of growth, the 13C and 15N enrichments (13C-excess and 15N-excess) in the roots, stems and leaves, and phytoliths, as well as the 13C-excess in AAs extracted from roots and stems and leaves, were quantified relatively to a control experiment in which no labelled AAs were added. The net uptake of 13C derived from the labeled AAs supplied to the nutritive solution (AA-13C) by Festuca arundinacea represented 4.5% of the total AA-13C supply. AA-13C fixed in the plant represented only 0.13% of total C. However, the experimental conditions may have underestimated the extent of the process under natural and field conditions. Previous studies showed that 15N and 13C can be absorbed by the roots in several organic and inorganic forms. In the present experiment, the fact that phenylalanine and methionine, that were supplied in high amount to the nutritive solution, were more 13C-enriched than other AAs in the roots and stems and leaves strongly suggested that part of AA-13C was absorbed and translocated in its original AA form. The concentration of AA-13C represented only 0.15% of the phytolith C (phytC) but was still 1.5 times higher in phytoliths than in leaves supporting that, ultimately, AA-13C was preferentially fixed in organic compounds subject to occlusion in phytoliths. Plausible forms of AA-13C and AA-15N absorbed and translocated, AA-13C fixation in phytoliths and implication of our finding for our understanding of the C cycle at the plant-soil interface are discussed. [ABSTRACT FROM AUTHOR]

Background and Aims: The carbon (C) balance of boreal terrestrial ecosystems is sensitive to increasing temperature, but the direction and thresholds of responses are uncertain. Annual C uptake in Picea and other evergreen boreal conifers is dependent on seasonal- and cohort-specific photosynthetic and respiratory temperature response functions, so this study examined the physiological significance of maintaining multiple foliar cohorts for Picea mariana trees within an ombrotrophic bog ecosystem in Minnesota, USA. Methods: Measurements were taken on multiple cohorts of needles for photosynthetic capacity, foliar respiration (Rd) and leaf biochemistry and morphology of mature trees from April to October over 4 years. The results were applied to a simple model of canopy photosynthesis in order to simulate annual C uptake by cohort age under ambient and elevated temperature scenarios. Key Results: Temperature responses of key photosynthetic parameters [i.e. light-saturated rate of CO2 assimilation (Asat), rate of Rubisco carboxylation (Vcmax) and electron transport rate (Jmax)] were dependent on season and generally less responsive in the developing current-year (Y0) needles compared with 1-year-old (Y1) or 2-year-old (Y2) foliage. Temperature optimums ranged from 18·7 to 23·7, 31·3 to 38·3 and 28·7 to 36·7°C for Asat, Vcmax and Jmax, respectively. Foliar cohorts differed in their morphology and photosynthetic capacity, which resulted in 64% of modelled annual stand C uptake from Y1&2 cohorts (LAI 0·67m²m-2) and just 36% from Y0 cohorts (LAI 0·52m²m-2). Under warmer climate change scenarios, the contribution of Y0 cohorts was even less; e.g. 31% of annual C uptake for a modelled 9°C rise in mean summer temperatures. Results suggest that net annual C uptake by P. mariana could increase under elevated temperature, and become more dependent on older foliar cohorts. Conclusions: Collectively, this study illustrates the physiological and ecological significance of different foliar cohorts, and indicates the need for seasonal- and cohort-specific model parameterization when estimating C uptake capacity of boreal forest ecosystems under ambient or future temperature scenarios. [ABSTRACT FROM AUTHOR]

Plants produce secondary metabolites promoting adaptation to changes in the environment and challenges by pathogenic microorganisms. A future climate with increased temperature and CO 2 and ozone levels will likely alter the chemical composition of plants and thereby plant–pathogen interactions. To investigate this, barley was grown at elevated CO 2 , temperature and ozone levels as single factors or in combination resembling future climatic conditions. Increased basal resistance to the powdery mildew fungus was observed when barley was grown under elevated CO 2 , temperature and ozone as single factors. However, this effect was neutralized in the combination treatments. Twenty-five secondary metabolites were putatively identified in healthy and diseased barley leaves, including phenylpropanoids, phenolamides and hydroxynitrile glucosides. Accumulation of the compounds was affected by the climatic growth conditions. Especially elevated temperature, but also ozone, showed a strong impact on accumulation of many compounds, suggesting that these metabolites play a role in adaptation to unfavorable growth conditions. Many compounds were found to increase in powdery mildew diseased leaves, in correlation with a strong and specific influence of the climatic growth conditions. The observed disease phenotypes could not be explained by accumulation of single compounds. However, decreased accumulation of the powdery mildew associated defense compound p-coumaroylhydroxyagmatine could be implicated in the increased disease susceptibility observed when barley was grown under combination of elevated CO 2 , temperature and ozone. The accumulation pattern of the compounds in both healthy and diseased leaves from barley grown in the combination treatments could not be deduced from the individual single factor treatments. This highlights the complex role and regulation of secondary metabolites in plants’ adaptation to unfavorable growth conditions. [ABSTRACT FROM AUTHOR]

The carbon (C) budget of managed grassland in a cool-temperate region of Japan was estimated using a combination of eddy covariance and the biometric method for five years, to evaluate the effect of manure application. Chemical fertilizer was applied to the fertilizer (F) plot at a rate of 79 ± 20 kg N ha−1 yr−1. In the manure (M) plot, dairy cattle manure was applied at a rate of 10 Mg fresh matter ha−1 yr−1(1923 ± 407 kg C ha−1 yr−1, 159 ± 68 kg N ha−1 yr−1). There was no significant difference in seasonal gross primary production (GPP) and harvest between the treatment plots, indicating that both fertilizer and manure can increase the biomass production. Annual net ecosystem production (NEP) and ecosystem respiration (RE) was significantly different between the treatment plots. The difference in RE, and between M and F plots approximates heterotrophic respiration of manure (RHm), which ranged from 0.9 to 1.3 Mg C ha−1 yr−1. Average annual RHm was 1.1 ± 0.4 Mg C ha−1 yr−1, and accounted for 56% of the total amount of applied manure C. The annual net biome production (NBP) in the M plot (from 0.0 to 1.5 Mg C ha−1 yr−1) was significantly higher than in the F plot (−1.4 to 0.5 Mg C ha−1 yr−1). The long-term effect of manure application combined with chemical fertilizer did not reduce grass production compared with chemical fertilizer only; however, manure application decreased the NEP throughout manure decomposition, and long-term manure application enhanced the NBP. [ABSTRACT FROM PUBLISHER]

We tested the hypothesis that greening of the floral (involucral) bracts of Dalechampia scandens blossoms after pollination (when bracts are white) increases carbon assimilation and provides photosynthate to developing seeds., We investigated the importance of the involucral bracts for the process of seed development in two ways. First, we removed or shaded bracts of hand-pollinated blossoms to prevent their photosynthesis and tested the effects of these manipulations on seed development. Secondly, we measured the photosynthetic rate of blossoms with white vs. green bracts and compared these rates with those of leaves., After four weeks of development, seeds from blossoms with bracts removed or shaded were lighter than those produced by unmanipulated blossoms. Furthermore, although the area-based photosynthetic rate of green bracts was much lower than that of leaves, it was much greater than that of white bracts. Estimates of the daily carbon budget based on these measurements indicate that photosynthesis in green bracts is sufficient to meet the respiratory demand of the whole blossom, but not so in white bracts., Our results support the hypothesis that colour change in D. scandens bracts allows carbon assimilation that contributes to the carbon demand of nearby developing seeds. [ABSTRACT FROM AUTHOR]

Raw materials assume different forms during their use and thereby develop a multiplicity of effects upon the political environment. This article demonstrates the method of sectoral mass flow analysis using the example of the raw material wood. Under conditions of limited resources, market analysis methods must change from single flow analysis in an open (unlimited) system to interactive flow analysis in a closed (limited) system. The method of the wood resource balance is introduced, with its basic elements of resource monitoring, bottom-up approach, data counterchecking and conversion factors. The method is applicable for manifold research topics. This is shown in three examples. The wood flow analysis represents a total resource assessment including all wood products in all process steps from forest to disposal. Based on the wood flow analysis, calculation schemes show how cascading factors can be calculated on a constant basis. Finally the CO 2 effects of total wood use are calculated on a continuous basis. [ABSTRACT FROM AUTHOR]