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The value 8.46 MJ m −2 d −1 is generally indicated as the radiation threshold for vegetable crops in tropical and subtropical climates. However, several studies indicate that mini tomato plants can be cultivated in greenhouse under lower solar radiation conditions. Therefore, the establishment of the actual radiation threshold for this group of tomatoes is necessary. The objective of this study was to define the relative influence of solar radiation and temperature on plant growth, and determine the lowest value of incoming global solar radiation inside the greenhouse by which there is a significant plant dry matter accumulation in the mild autumn/winter of southern Brazil. Mini tomato plants of hybrids Cherry Wanda ® and Grape Dolcetto ® were grown in NFT hydroponic system. Nineteen plant samples were collected periodically to obtain plant dry matter, leaf area, number of leaves, plant height and absolute and relative growth rates. The variables were related to the data of incoming global solar radiation and temperature inside the greenhouse. The results were submitted to analyses of variance, regression and clustering test. Cherry and Grape plants presented similar responses to the variation of solar radiation and temperature. However, Cherry plants presented greater leaf area and growth under these conditions. Temperature had an indirect influence on plant growth, while incoming solar radiation presented a direct influence on all evaluated variables. The solar radiation threshold for both cultivars of mini tomato was 3.63 MJ m −2  d −1 . [ABSTRACT FROM AUTHOR]

Fertilizer application often significantly affects soil quality and crop productivity, thus, can affect soil greenhouse gas (GHG) emissions and nitrogen use efficiency (NUE) as well. However, the impacts have not been well documented under double maize cropping system in subtropical China. Based on a thirty-year field experiment with five fertilization treatments (i.e. no fertilizer (CK), organic manure (OM), N, NPK and NPK plus OM (NPKM)), maize cultivar (Yedan 13) was planted both at the early maize season and late maize season, we assessed the impacts of different fertilizer application on nitrous oxide (N 2 O) and methane (CH 4 ) emissions, grain yield and NUE. Compared to the NPK, manure application (i.e. OM and NPKM) significantly increased N 2 O emissions, and maize yield. Nevertheless, there was no significant difference in yield–scaled global warming potential (GWP) among NPK, OM, and NPKM. Manure application increased soil pH, soil organic carbon, and soil total N, suggesting it can improve soil quality. The NPKM treatment had the highest N uptake, but in terms of NUE, it was lower than OM, due to double N application. Our results suggest that manure application can compensate its negative impacts on N 2 O emission through improving soil quality, maize yield and N use efficiency. [ABSTRACT FROM AUTHOR]

Abstract: Central European grasslands are characterized by a wide range of different management practices in close geographical proximity. Site‐specific management strategies strongly affect the biosphere–atmosphere exchange of the three greenhouse gases (GHG) carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4). The evaluation of environmental impacts at site level is challenging, because most in situ measurements focus on the quantification of CO2 exchange, while long‐term N2O and CH4 flux measurements at ecosystem scale remain scarce. Here, we synthesized ecosystem CO2, N2O, and CH4 fluxes from 14 managed grassland sites, quantified by eddy covariance or chamber techniques. We found that grasslands were on average a CO2 sink (−1,783 to −91 g CO2 m−2 year−1), but a N2O source (18–638 g CO2‐eq. m−2 year−1), and either a CH4 sink or source (−9 to 488 g CO2‐eq. m−2 year−1). The net GHG balance (NGB) of nine sites where measurements of all three GHGs were available was found between −2,761 and −58 g CO2‐eq. m−2 year−1, with N2O and CH4 emissions offsetting concurrent CO2 uptake by on average 21 ± 6% across sites. The only positive NGB was found for one site during a restoration year with ploughing. The predictive power of soil parameters for N2O and CH4 fluxes was generally low and varied considerably within years. However, after site‐specific data normalization, we identified environmental conditions that indicated enhanced GHG source/sink activity (“sweet spots”) and gave a good prediction of normalized overall fluxes across sites. The application of animal slurry to grasslands increased N2O and CH4 emissions. The N2O‐N emission factor across sites was 1.8 ± 0.5%, but varied considerably at site level among the years (0.1%–8.6%). Although grassland management led to increased N2O and CH4 emissions, the CO2 sink strength was generally the most dominant component of the annual GHG budget. [ABSTRACT FROM AUTHOR]

Biochar effect on greenhouse gases mitigation was mainly studied in amended mineral soils and little information is available for peat-based growing media (PBGMs) used in greenhouse production. We established a 58-d PBGM microcosm incubation study to investigate the effect of different biochars and a compost on the mineralization of carbon (C) and nitrogen (N) and on mitigation of CO 2 , CH 4 and N 2 O. Biochars and compost were added respectively at a rate of 15% and 4% (v/v) and a weekly mineral N fertilizer was applied. Five biochars were produced from three feedstocks at three pyrolysis temperatures: maple bark 400 °C (M400), 550 °C (M550) and 700 °C (M700); willow chips 400 °C (W400); and pine chips 700 °C (P700). Biochar addition increased C and decreased N availability in fertigated PBGMs. The highest microbial biomass C and N were obtained ( p  < 0.05) with M400 rich in volatile matter, and with compost treatments. Microbial enzymatic activity was lower ( p  < 0.05) in maples and W400 treated PBGMs than in P700 and control. Addition of compost and maple biochars produced at 400 °C and 550 °C lowered the microbial metabolic quotient. The highest mitigation efficiency of CO 2 was obtained with M550 which released in 58-d, 50% less than other treatments. The total cumulative CH 4 emission was also 21% lower in maple PBGMs than in control or P700. The total cumulative N 2 O emission was reduced by 66% by the addition of alkaline biochars (M400, M550, M700 and W400) in the PBGM without compost. This mitigation can be associated with the important ammonium adsorption by these biochars which can slow the nitrification process, or to a probable increase in the N 2 /N 2 O ratio. Compost addition had no effect on the N 2 O fluxes from all treatments. This work indicates that biochars can be favorably used as an amendment to PBGMs for the development of a sustainable greenhouse production. [ABSTRACT FROM AUTHOR]

Globally, agriculture is a significant contributor to greenhouse gas emissions. The environment (e.g., soils and climate) and management influence agricultural greenhouse gas emissions and the potential to reduce emissions. For agriculture to contribute to greenhouse gas abatement in the long term, it is important to identify low-cost mitigation actions that farmers can adopt. It is hypothesized that greenhouse gas abatement potential and the associated costs will differ substantially between environments in Australia. Seven alternative management scenarios were identified as both suitable for adoption across different grain growing environments in Australia and potentially able to provide greenhouse gas abatement. The Agricultural Production Systems Simulator was used to simulate these alternative management scenarios over a 25-year period and analyze the potential for Australian grain farmers, across contrasting environments, to increase soil organic carbon stocks and/or reduce nitrous oxide emissions. This analysis was paired with a whole-farm economic analysis to determine the implications of the different greenhouse gas abatement scenarios on farm profitability. Results from case studies in Australia's three main grain growing regions demonstrate that significant heterogeneity exists in the biophysical potential and costs to reduce greenhouse gas emissions across locations. The maximum predicted abatement potential for the case study sites varied from 0.34 to 2.03 metric tons of carbon dioxide equivalents per hectare per year. In most simulations, greenhouse gas abatement came at a cost to farmers ranging from 0.11 Australian dollars (AUD) to more than 300 AUD per metric ton of abated carbon dioxide equivalent. This is the first study to explore the costs of mitigation including multiple greenhouse gases and grain farming case studies across Australia. These findings can inform the future development of effective climate change mitigation policies, which frequently use national default values in their design. [ABSTRACT FROM AUTHOR]

The comprehensive impacts of different nitrogen management and crop establishment on greenhouse (GHG) fluxes are not well documented. GHG emissions from rice paddies under different nitrogen management and crop establishment merit attention because nitrogen fertilizer is indiscriminately used for the intensification of rice cultivation. Field trials were conducted to assess methane (CH 4 ), nitrous oxide (N 2 O) and carbon dioxide (CO 2 ) emissions, labile C pools, microbial population and enzymatic activities in rice soil under different crop establishment and nitrogen (N) management practices. The crop establishment methods included aerobic rice (AR) that involved dry direct seeding under non puddled and non-flooded situation and puddled transplanted rice (PTR) under flooded condition. Nitrogen management practices were control, 100 kg N ha −1 as prilled urea (PU) and applied conventionally, 100 kg N ha −1 as neem coated urea (NCU), applied conventionally, 100 kg N ha −1 as PU, applied on the basis of customized leaf colour chart (CLCC) recommendation, 100 kg N ha −1 as NCU, applied on the basis of CLCC recommendation, 100 kg N ha −1 as PU and farm yard manure (FYM) in 1:1 ratio, applied conventionally. Cumulative seasonal CH 4 emission was 73–75% less in AR as compared to PTR. But seasonal N 2 O and CO 2 emissions from soils were significantly higher in AR. Global warming potential of AR was comparatively less than PTR but yield loss in AR caused greenhouse gas intensity (GHGI) of AR to be at par with that of PTR. Inclusion of FYM along with PU reduced N 2 O emission and maintained significantly higher ( P ≤ 0.05) microbial biomass carbon concentration, nitrifiers, Azotobacte r and Azospirillum population and dehydrogenase, β-glucosidase and urease activities in soils of AR and PTR. Real time N application according to leaf colour chart and use of slow release N fertilizers can reduce N 2 O emission, minimize yield loss and lower GHGI of AR. [ABSTRACT FROM AUTHOR]

Grassland production systems offer feedstock for power production based on biogas in Germany. In the future, additional potential grassland will be made available due to further concentration of cattle production in areas that possess comparative advantages for milk and meat production. This study assesses grassland as a feedstock for biogas production in Germany from both an economic and ecological point of view by considering regional production conditions and plant-specific factors. Regional production costs and greenhouse gas emissions for grasslands are calculated within the federal states of Bavaria, Lower Saxony and Schleswig-Holstein, which represent hotspots for German biogas production. A linear model approach is used to optimize the feedstock mix of each biogas plant located in one of these exemplary regions. In a scenario-based analysis, the opportunity costs for energy crops cultivated on arable land are considered to depict a shortage of arable land as an economic advantage of grasslands. Similar to EU biofuel production, the linear model considers the greenhouse gas mitigation potential for power production based on biogas and differing costs of CO 2 emission rights. Greenhouse gas emissions are calculated both with and without iLUC factors to highlight the differences between arable land and grasslands with respect to limited availabilities and the consequences of greenhouse gas emissions. The results show that grasslands could be a reasonable feedstock for biogas production, especially in the northern part of Germany, if iLUC factors are considered and if a greenhouse gas mitigation potential is required that includes high prices for CO 2 emission rights. [ABSTRACT FROM AUTHOR]

Nitrogen (N) cycling within agriculture constitutes a source of direct and indirect emissions of the potent greenhouse gas nitrous oxide (N 2 O). We analysed relationships between N 2 O emissions and C and N balances of four arable cropping systems under conventional or organic management within a long-term experiment on a loamy sand soil at Foulum in Denmark. All cropping systems included winter wheat, a leguminous crop (faba bean or grass-clover), potato and spring barley grown in different 4-crop rotations varying in strategies for N supply (fertilizer/manure type and rate, use of catch crops and green manure). Crops in both organic and conventional systems received N at rates below the optimum for crop production. Soil N 2 O emissions were monitored in 2008–2009 in six selected crops which could be combined with data from other monitoring programs to calculate N 2 O emission factors for each of the 16 crops and four entire crop rotations. Accumulated annual N 2 O emissions were on average 0.8 to 0.9 kg N ha −1 y −1 and did not differ significantly between rotations. Soil N inputs in above- and belowground crop residues from main crops and catch crops were quantified by field measurements. Average nitrate-N leaching losses ranged from 39 to 56 kg N ha −1 y −1 and were lowest in rotations with catch crops; leaching was not correlated with N surplus or N input in fertilizer or manure. Crop yields of the organic rotations were 25 to 37% lower than in identical conventional rotations. As a consequence, yield-scaled N 2 O emissions were lower under conventional management compared with the organic alternatives. There was no significant correlation between N 2 O emissions and N input in fertilizer/manure, neither for annual emissions nor spring emissions. In contrast, N 2 O emissions were correlated with N input in residues from the previous main crop and catch crop (r = 0.56, p < 0.01). This indicates that, besides nitrogen, degradable carbon provides an important and estimable driver for N 2 O emissions in arable cropping systems. [ABSTRACT FROM AUTHOR]

China is the largest country in grain production and consumption with the greatest emission of greenhouse gas (GHG) in the world. To learn the historical changes and regional differences in GHG emission of the major grain crop production can provide important references to the mitigation of GHG emission in the country and other similar countries. Therefore, we quantified the carbon footprints of rice ( Oryza sativa L.), wheat ( Triticumaestivum L.) and maize ( Zea mays L.) production based on agricultural inputs in the country over the period of 1978–2012. The results showed that area-scaled carbon footprint of rice, wheat and maize production increased gradually from 1286, 937 and 895 kg carbon dioxide equivalent (CO 2 -eq) ha −1 in 1978–2682, 2978 and 2294 kg CO 2 -eq ha −1 in 2012, respectively, and the average increase rates for the three crops were correspondingly 41, 60 and 41 kg CO 2 -eq ha −1 a −1 . During the last ten years, however, all the average yield-scaled carbon footprints of rice, wheat and maize decreased by 0.11 kg CO 2 -eq kg −1 10a −1 . Chemical fertilizer contributed the largest ratio to the total GHG emission by 66, 68 and 76% for rice, wheat and maize, respectively. Significant increasing contribution ratio to the carbon footprint was found in the electricity used for crop irrigation. There were large differences in both the area- and yield-scaled carbon footprints among the cropping regions with the lowest GHG emission occurring in the major cropping regions. Our findings indicate a great potential to reduce GHG emission of grain production through optimizing the spatial layout of cropping region and enhancing chemical fertilizer use efficiency. Further efforts also need to be made on water-saving irrigation to decrease the electricity usage. [ABSTRACT FROM AUTHOR]

Paddy rice is the main cropping system in Southeast Asia. However, water scarcity arising from competition from other sectors, rainfall variability and climate change increasingly challenges global rice production. One option to adapt to lower water availability is switching from paddy rice to less irrigation intensive upland cropping systems. Such land management change (LMC) is likely to significantly affect ecosystem carbon and nitrogen cycling and its greenhouse gas (GHG) balance. This study evaluates how well the ecosystem model LandscapeDNDC is able to simulate observed emissions of methane (CH 4 ), nitrous oxide (N 2 O) and carbon dioxide (CO 2 ) from different tropical cropping rotations, i.e., double- and triple-cropped paddy rice, aerobic rice–paddy rice and maize–paddy rice (rice: O. sativa , maize: Zea mays ) and how management changes to rice dominated lowland systems will affect the GHG balance on short (a few years) and long (several decades) time scales. LandscapeDNDC predicts seasonal emissions of CH 4 and N 2 O across different cropping rotations (including LMC) with R 2 values of 0.85 and 0.78 and average underestimations of 15 and 14%, respectively. In addition to emissions of CH 4 and N 2 O, LandscapeDNDC also captures the long-term development of soil organic carbon (SOC). Soil oxygen status, growth of photosynthetic active aquatic biomass as well as decomposability of harvest residues significantly influence SOC development. Simulation results demonstrate that short-term GHG balances after LMC considerably differ from long-term balances. Simulated total GHG emissions three years after LMC are highest for upland crop − paddy rice rotations due to pronounced decomposition of soil organic carbon. In contrast, the total GHG emissions are highest for double cropping of paddy rice and are clearly dominated by CH 4 emissions over a longer period of several decades. Simulation results suggest that approx. 2.8–3.4 t C ha −1 yr −1 residue incorporation after harvest is needed to achieve stable SOC stocks in mixed upland crop–paddy rice systems after LMC from double-cropped paddy rice systems. [ABSTRACT FROM AUTHOR]

Dense planting and less basal nitrogen (N) fertilization have been recommended to further increase rice ( Oryza sativa L.) grain yield and N use efficiency (NUE), respectively. The objective of this study was to evaluate the integrative impacts of dense planting with reduced basal N application (DR) on rice yield, NUE and greenhouse gas (GHG) emissions. Field experiments with one conventional sparse planting (CK) and four treatments of dense planting (increased seedlings per hill) with less basal N application were conducted in northeast China from 2012 to 2013. In addition, a two-factor experiment was conducted to isolate the effect of planting density and basal N rate on CH 4 emission in 2013. Our results show that an increase in planting density by about 50% with a correspondingly reduction in basal N rate by about 30% (DR1 and DR2) enhanced NUE by 14.3–50.6% and rice grain yield by 0.5–7.4% over CK. Meanwhile, DR1 and DR2 reduced GWP by 6.4–12.6% and yield-scaled GWP by 7.0–17.0% over CK. According to the two-factor experiment, soil CH 4 production and oxidation and CH 4 emission were not affected by planting density. However, reduced basal N rate decreased CH 4 emission due to it significantly reduced soil CH 4 production with a smaller reduction in soil CH 4 oxidation. The above results indicate that moderate dense planting with less basal N application might be an environment friendly mode for rice cropping for high yield and NUE with less GHG emissions. [ABSTRACT FROM AUTHOR]

Increased nitrogen (N) deposition within the context of both warming and grazing is relevant to understand the response of greenhouse gases fluxes (GHG) (i.e. CO 2 , CH 4 and N 2 O fluxes) for alpine meadow ecosystems to projected changes in the environment. A previous controlled warming and grazing experiment only included no warming with no grazing (NWNG), no warming with grazing (NWG), warming with no grazing (WNG) and warming with grazing (WG) from 2006 to 2010. N fertilization was added to the experimental setup to determine the effects of warming, grazing and N fertilization on GHG fluxes in an alpine meadow on the Tibetan Plateau during the growing seasons from 2010 to 2012. Sheep grazing was utilized during the growing season from 2006 to 2010 and cutting was used as simulation of grazing during the non-growing seasons in 2011 and 2012. Warming significantly increased average seasonal CO 2 emission by 10%, and nitrogen addition increased average seasonal CH 4 uptake by 14% during the growing seasons in the dry years of 2011 and 2012. Warming increased average seasonal CH 4 uptake by 32–46% over the 3-year period, and grazing increased annual average N 2 O emission by 62% only in 2010. N fertilization alone did not significantly affect CO 2 and N 2 O fluxes during the experimental period. The interactive effects of warming, grazing/cutting and N fertilization effect on daily CH 4 or daily N 2 O flux depended on sampling date. Ecosystem CO 2 emission was mainly affected by soil temperature and plant aboveground net primary production (ANPP), which explained about 55% and 18% of its variation. Soil moisture and ANPP could explain 17% and 8% of the variation of CH 4 uptake in the region. Our results suggest that the stimulating effect of warming on ecosystem respiration still occurs in 2011 and 2012 after warming for seven years. Moreover, our results imply that moderate grazing/cutting may be preferred compared with no grazing or no cutting because its negative effect on GHG fluxes was small, and interactive effect of warming, grazing/cutting and increased N deposition on GHG emission could be neglected in the alpine meadow. [ABSTRACT FROM AUTHOR]

Soil properties and crop evapotranspiration ( ET ) are two important factors influencing variations in tomato yield and fruit quality. Quantifying the effect of soil properties and ET on variations in yield and fruit quality is critical for adopting precision irrigation and fertilization management practices in a greenhouse. The experiments were conducted to investigate the variations in drip-irrigated tomato yield and quality parameters and their relationships with spatial variability of soil properties from 0 to 20 cm depth and ET from 0 to 60 cm depth in a greenhouse of Northwest China during March to July 2012 (the 1st season) and October 2012 to April 2013 (the 2nd season). The results showed that tomato yield was more variable than any quality parameters. The coefficients of variation for yield, quality parameters and ET were 18.2, 8.6–14.5 and 8.2–20.0% in the 1st season, and 11.8, 6.3–9.8 and 9.1–11.5% in the 2nd season, respectively. In both seasons, yield was significantly positively correlated with soil moisture content ( θ v ), nitrate nitrogen content and ET , while significantly negatively related to sand content, bulk density and ammonium nitrogen content in soil. The contents of total soluble solids ( TSS ), vitamin C ( VC ) and soluble sugar ( SS ) in fruit and fruit firmness ( Fn ) were significantly negatively related to θ v and ET . The principal component analysis (PCA) was conducted for combination of the selected soil properties and ET , and the retained principal components (PCs) were used in stepwise regression with yield and quality parameters. PCA results showed that a maximum of 83% of the total variability in soil properties and ET was explained by the first four PCs. The stepwise regression analysis indicated that soil properties and ET could explain 81, 65, 66, 66, 64 and 60%, and 69, 47, 35, 52, 33 and 28% of total variance in tomato yield, TSS , VC , SS , organic acid and Fn in the 1st and 2nd season, respectively. The selected soil properties and ET were more important in estimating yield than quality parameters which were difficult to accurately predict in the greenhouse. [ABSTRACT FROM AUTHOR]

The most important issue which has attracted the attention of many scientists is the climate change and global warming due to greenhouse gas emission which has caused the world faced with a great human and environmental disaster. In this study, the amount of greenhouse gas (GHG) emissions was estimated in the semi-traditional and semi-mechanized rice production systems in Dargaz region, Iran. All the agricultural and consuming inputs procedures responsible for greenhouse gas emissions were collected and recorded in both systems. The amount of GHG emission in semi-traditional and semi-mechanized was 813.17 and 968.31 kg CO2-eq ha-1, respectively. The fuel consumption with the share of 38.22% in semi-traditional method and 43.32% in semi-mechanized system had the largest share in GHG emission and using Nitrogen fertilizer on farms with the share of 31.97% in semi-traditional method and 26.91% in semi-mechanized system is in the second place of GHG emission. The semi-traditional system had greater GHG emissions in the unit of tone of harvested grain and unit of energy output. The use of alternative methods such as conservation tillage and organic fertilizers can be effective in improving the environmental status of the production area. [ABSTRACT FROM AUTHOR]

Biofuels are seen as an effective means to reduce greenhouse gas (GHG) emissions of energy production. However, the cultivation phase of agribiomass-based biofuel production in particular can cause significant GHG emissions and additional environmental problems, such as water pollution and biodiversity loss. In this study, the aim was to develop a comprehensive environmental sustainability framework for agribiomass chains. The chosen environmental impact categories (climate change, eutrophication, soil erosion, soil organic matter decline, ecotoxicity, biodiversity, use of non-renewable resources, water use, and production efficiency) were selected based on literature and the views of energy companies and interest groups. The framework was tested with two Finnish agribiomass chains: barley (Hordeum vulgare L.) straw (for combustion) and turnip rape (Brassica rapa ssp. oleifera DC.) (for biodiesel). Relevant improvement options were identified and their impact reduction potential was assessed. The GHG emissions of both selected bioenergy sources were less than those of their fossil fuel references. Critical challenges for both studied agribiomass chains currently include eutrophication, soil organic matter decline and the use of non-renewable natural resources. The indicator values could be markedly improved by the selected improvement options, of which the most important is optimal yield. Better distributions of manure and soil fertility improvement (carbon stock and pH) were identified as the most important long-term goals for improving sustainability. [ABSTRACT FROM AUTHOR]

The effect of draining crop fields during the wheat season on the soil CH4 and N2O emissions during the rice season in this article. There were four treatments: traditional cultivation during the wheat season + cultivation without fertilization during the rice season (CK1 field), traditional cultivation during the wheat season + traditional cultivation during the rice season (CK2 field), draining the fields through shallow furrows + traditional cultivation during the rice season (CQ field) and draining the fields through deep furrows + traditional cultivation during the rice season (CS field). The results are listed as follows. (1) Draining the field through furrows during the wheat season significantly reduced the CH4 and N2O emissions during the rice season. Compared with the CKi field, the total CH4 emissions from the CQ and CS fields decreased by 43.1% and 39.9%, respectively; compared with the CK2 field, the total CH4 emissions from the CQ and CS fields decreased by 58.1% and 55.7%, respectively; compared with the CK2 field, the total N2O emissions from the CQ and CS fields decreased by 33.6% and 32.7%, respectively. N2O emissions from the CQ and CS fields caused by fertilization declined by 44.0% and 42.9% compared with that from the CK2 field. (2) Draining the wheat field in winter changed the CH4 emission pattern during the following rice season. The daily average CH4 emission flux from the winter flooded CK1 and CK2 fields were comparable before the field sunning and after the re-flooding and the fluxes from the drained CQ and CS fields before the field sunning were close to that from the CK1 and CK2 fields but were significantly greater than that from the drained CQ and CS fields after the field re-flooding. (3) The soil CH4 emission flux was significantly negatively correlated to the soil Eh. But the correlation was weakened by the drainage treatment in the wheat season. In summary, draining the crop field in the wheat season should be an effective approach to reducing soil greenhouse gas emissions in the rice season. [ABSTRACT FROM AUTHOR]

As pressure on water resources increases, alternative practices to conserve water in paddies have been developed. Few studies have simultaneously examined the effectiveness of different water regimes on conserving water, mitigating greenhouse gases (GHG), and maintaining yields in rice production. This study, which was conducted during the drought of 2013, examined all three factors using a split-plot experiment with two rice varieties in a no-till paddy managed under three different water regimes: 1) continuous flooding (CF), 2) flooded and wet intermittent irrigation (FWI), and 3) flooded and dry intermittent irrigation (FDI). The Methane (CH 4 ) and nitrous oxide (N 2 O) emissions were measured using static chamber-gas measurements, and the carbon dioxide (CO 2 ) emissions were monitored using a soil CO 2 flux system (LI-8100). Compared with CF, FWI and FDI irrigation strategies reduced CH 4 emissions by 60% and 83%, respectively. In contrast, CO 2 and N 2 O fluxes increased by 65% and 9%, respectively, under FWI watering regime and by 104% and 11%, respectively, under FDI managed plots. Although CO 2 and N 2 O emissions increased, the global warming potential (GWP) and greenhouse gas intensity (GHGI) of all three GHG decreased by up to 25% and 29% ( p < 0.01), respectively, using water-saving irrigation strategies. The rice variety also affected yields and GHG emissions in response to different water regimes. The drought-resistance rice variety (HY3) was observed to maintain yields, conserve water, and reduce GHG under the FWI irrigation management compared with the typical variety (FYY299) planted in the region. The FYY299 only had significantly lower GWP and GHGI when the yield was reduced under FDI water regime. In conclusion, FWI irrigation strategy could be an effective option for simultaneously saving water and mitigating GWP without reducing rice yields using drought-resistant rice varieties, such as HY3. [ABSTRACT FROM AUTHOR]

Medicago sativa L. (alfalfa) can exhibit photosynthetic down-regulation when grown in greenhouse conditions under elevated atmospheric CO 2 . This forage legume can establish a double symbiosis with nitrogen fixing bacteria and arbuscular mycorrhizal fungi (AMF), which may increase the carbon sink effect of roots. Our aim was to assess whether the association of alfalfa with AMF can avoid, diminish or delay the photosynthetic acclimation observed in previous studies performed with nodulated plants. The results, however, showed that mycorrhizal (M) alfalfa at the end of their vegetative period had lower carbon (C) discrimination than non-mycorrhizal (NM) controls, indicating photosynthetic acclimation under ECO 2 in plants associated with AMF. Decreased C discrimination was due to the acclimation of conductance, since the amount of Rubisco and the expression of genes codifying both large and small subunits of Rubisco were similar or slightly higher in M than in NM plants. Moreover, M alfalfa accumulated a greater amount of soluble sugars in leaves than NM plants, thus favoring a down-regulation effect on photosynthetic rates. The enhanced contents of sugars in leaves coincided with a reduced percentage of arbuscules in roots, suggesting decreased sink of carbohydrates from shoots to roots in M plants. The shorter life cycle of alfalfa associated with AMF in comparison with the NM controls may also be related to the accelerated photosynthetic acclimation in M plants. Further research is needed to clarify to what extent this behavior could be extrapolated to alfalfa cultivated in the field and subjected to periodic cutting of shoots under climatic change scenarios. [ABSTRACT FROM AUTHOR]

The resistance of 28 Spanish olive cultivars to Verticillium dahliae was evaluated in an experiment conducted under greenhouse conditions, by impregnating plant roots with a semisolid fluid mass of a mixture of culture medium and the conidia and mycelium of the fungus. Five-month-old olive plants were inoculated with a cotton defoliating isolate of V. dahliae. 'Frantoio' and 'Picual' were used as resistant and susceptible reference cultivars, respectively. Cultivars were assessed on the basis of final values of the area under the disease progress curve, mean severity of symptoms, and mortality at 26 weeks following inoculation. Verticillium wilt disease developed more slowly and reached lower values of these parameters than those normally recorded in previous studies conducted in growth chambers, using root-dip inoculation in a conidial suspension of the pathogen. However, most of the evaluated cultivars exhibited susceptible or moderately susceptible reactions to the infections caused by V. dahliae. In particular, a group of eight cultivars, from the same group as 'Picual', such as 'Manzanilla de Abla', 'Manzanilla del Centro' and 'Negrillo de Iznalloz', were significantly more susceptible than 'Frantoio'. Conversely, 'Escarabajillo', 'Menya' and 'Sevillana de Abla' exhibited a high level of resistance to the disease, no dead plants, and vegetative recovery. Field experiments are currently being carried out to confirm the level of resistance assigned to these last genotypes. If confirmed, these genotypes will act as potential resistant genitors for inclusion in current olive breeding programs or for use as resistant rootstocks. [ABSTRACT FROM AUTHOR]

Anthropogenic activities are altering levels of greenhouse gases to the extent that multiple and diverse ecosystem processes are being affected. Two gases that substantially influence forest health are atmospheric carbon dioxide ( CO2) and tropospheric ozone ( O3). Plant chemistry will play an important role in regulating ecosystem processes in future environments, but little information exists about the longitudinal effects of elevated CO2 and O3 on phytochemistry, especially for long-lived species such as trees. To address this need, we analysed foliar chemical data from two genotypes of trembling aspen, Populus tremuloides, collected over 10 years of exposure to levels of CO2 and O3 predicted for the year 2050. Elevated CO2 and O3 altered both primary and secondary chemistry, and the magnitude and direction of the responses varied across developmental stages and between aspen genotypes. Our findings suggest that the effects of CO2 and O3 on phytochemical traits that influence forest processes will vary over tree developmental stages, highlighting the need to continue long-term, experimental atmospheric change research. [ABSTRACT FROM AUTHOR]

Climate change is associated with atmospheric warming due to continuous increase in anthropogenic greenhouse gas concentration following the industrial revolution. The urban areas are more responsible for these changes. Europe for example has experienced a progressive warming +0.9 °C for 1901-2005. Climate change is unequivocal and represents a possible threat for patients affected by allergic conditions because it is related with an increased distribution and concentration of pollen. Higher temperature, wet condition (especially thunderstorms), wind speed, transition of cold fronts, environmental changes (allergenic pollens arrived in new areas), are mechanisms which involve changes of production, dispersion and allergen content of pollen. Prolonged and more severe pollen seasons are leading to worsened asthma and allergies. The interaction of pollen with urban air pollutants could also lead to an increased effect of aeroallergens on allergic patients, with a greater likelihood of the development of an allergic respiratory disease in sensitized subjects and exacerbation of symptomatic patients. Air pollution could induce damage to airways mucosa, thus promoting sensitization of the airways; also it could increase the expression of allergenic proteins (allergen contents of pollen produce by plants is increased by higher temperature and CO2 enriched atmosphere). By increasing pollen concentration or making the airways susceptible to allergens, the climate change and air pollution have a negative impact on human health. [ABSTRACT FROM AUTHOR]

Antipathogenic potential of 16 plants was evaluated in the form of aqueous extracts againstPeronosclerospora sorghi, causing downy mildew of sorghum. A novel method was developed in which conidial suspension and plant extracts were mixed individually and allowed to stand for 5 min and then used to inoculate the host by sprout-dip method. The sprouts thus inoculated were grown in pots, and disease incidence was observed. Three extracts (Parthenium hysterophorus, Duranta repensandOxalis latifolia) suppressed the disease at par with chemical fungicide (Mancozeb 75%). In form of spray,D. repensextract with tween-20 adjuvant (1.9% disease) performed closest behind mancozeb (0% disease), while negative control showed 21% disease incidence. Organic management of airborne inoculum of downy mildew of sorghum is feasible and preferable as compared to the use of chemical fungicides, considering human and environmental health concerns. Use of water extract keeps the technology simple so that it can be directly prepared and used by farmers. Short listing of three most effective water extracts would help in self-reliance of farmers, reducing their dependence on commercial products. [ABSTRACT FROM AUTHOR]

Abstract: Agricultural soils are main sources and sinks of the greenhouse gases carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). The source–sink function depends on soil characteristics, climate and management. Emission measurements usually quantify the net result of production, consumption and transport of these gases in the soil; they do not provide information about the depth distributions of the concentrations of these gases in the soil. Here we report on concentrations of CO2, CH4 and N2O in air of 300cm deep soil profiles, at resolutions of 30–50cm, over a full year. Gas samples were taken weekly in a long-term field experiment with an irrigated winter wheat–summer maize double cropping system, and four fertilizer N application rates (0, 200, 400 and 600kgNha−1 year−1). The results showed distinct differences in CH4, CO2 and N2O concentrations profiles with soil depth. The concentrations of CO2 in soil air increased with soil depth and showed a seasonal pattern with relatively high concentrations in the warm and moist maize growing season and relatively low concentrations in the winter-wheat growing season. In contrast, CH4 concentrations decreased with depth, and did not show a distinct seasonal cycle. Urea application did not have a large effect on CH4 or CO2 concentrations, neither in the topsoil nor the subsoil. Concentrations of N2O responded to N fertilizer application and irrigation. Application of fertilizer strongly increased grain and straw yields of both winter wheat and summer maize, relatively to the control, but differences in yield between the treatments N200, N400 and N600 were not statistically significant. However, it significantly increased mean N2O concentrations peaks at basically all soil depths. Interestingly, concentrations of N2O increased almost instantaneously in the whole soil profile, which indicates that the soil had a relatively high diffusivity, despite compacted subsoil layers. In conclusion, the frequent measurements, at high depth resolutions, of concentrations of CH4, CO2 and N2O in soil air under a winter wheat–summer maize double crop rotation provide detailed insight into the production, consumption and transport of these gases in the soil. Concentrations of CH4, CO2 and N2O responded differently to management activities and weather conditions. [Copyright &y& Elsevier]

Abstract: Lettuce greenhouse experiments were carried out from March to June 2011 in order to analyze how pesticides behave from the time of application until their intake via human consumption taking into account the primary distribution of pesticides, field dissipation, and post-harvest processing. In addition, experimental conditions were used to evaluate a new dynamic plant uptake model comparing its results with the experimentally derived residues. One application of imidacloprid and two of azoxystrobin were conducted. For evaluating primary pesticide distribution, two approaches based on leaf area index and vegetation cover were used and results were compared with those obtained from a tracer test. High influence of lettuce density, growth stage and type of sprayer was observed in primary distribution showing that low densities or early growth stages implied high losses of pesticides on soil. Washed and unwashed samples of lettuce were taken and analyzed from application to harvest to evaluate removal of pesticides by food processing. Results show that residues found on the Spanish preharvest interval days were in all cases below officially set maximum residue limits, although it was observed that time between application and harvest is as important for residues as application amounts. An overall reduction of 40–60% of pesticides residues was obtained from washing lettuce. Experimentally derived residues were compared with modeled residues and deviate from 1.2 to 1.4 for imidacloprid and azoxystrobin, respectively, presenting good model predictions. Resulting human intake fractions range from for imidacloprid to for azoxystrobin. [Copyright &y& Elsevier]

The area used for watermelon cultivation in South Korea peaked at 45,207 hectares in 1995, but it has declined in each of the successive years. In 2011, watermelon ranked sixth highest in seed sales for vegetable crops in South Korea. Diverse F1 hybrid cultivars with superior characteristics are produced mainly by the private sector for both the domestic market and overseas export. Breeding goals have shifted from high-yield and hypertrophic fruits for open-field culture to high-quality fruits resistant to soil-borne diseases and abiotic stresses for greenhouse culture. Consumers' and growers' preferences for watermelon now encompass a wide range of fruit sizes and colors, in addition to high functional contents such as citrullin and lycopene. However, sweetness is still a prerequisite for a high quality cultivar. Since grafting of watermelon to the rootstock of bottle gourd or zucchini is a critical cultivation method, seed sales of these two rootstocks is an important market in South Korea. Although development of new cultivars relies mainly on conventional breeding methods, molecular markers are being used in breeding programs of watermelon in South Korea. [ABSTRACT FROM PUBLISHER]

The aim of this investigation was to evaluate the effect of two contrasting seasons (fall and spring) and irrigation regimes (well-watered and drought-stressed plants) on the carbon exchange rate (CER) of pitahaya grown in a cold greenhouse in the Valley of México. Carbon exchange rate (CER) of one-year-old stems of pitahaya was studied over two periods of 24 h (November and April), in well-watered plants (every 15 days) and drought-stressed plants (irrigation suspended for four and five months before CER measurements in November and April, respectively). In November, when the relative humidity (RH) during the night was between 65 and 85%, watered plants with 88% of relative water content (RWC) showed two maximum CER peaks. The first CER peak declined slowly when the air temperature dropped from 11 to 7.4 °C and sharply at 6 °C. The second CER peak was reached when the air temperature was 12.2 °C. Drought-stressed plants (RWC = 60%) also showed two maximum peaks but at different times. The first one was when the air temperature was 8.8 °C and the second peak appeared when the air temperature was 6 °C. In April, when the night RH was between 35 and 59%, the watered plants (RWC = 88%) followed a similar pattern to the RH variation. Two peaks were recorded; the first declined at a slow rate when the air temperature shifted from 18 to 13.2 °C, and the second declined sharply when the air temperature shifted from 10 to 6 °C. Plants under drought stress (RWC = 34%) showed a trend towards CAM-idling. Results showed that both season and irrigation regime affected the carbon exchange rate of pitahaya. The destructive method, using the portable photosynthesis system (LI-6200), was shown to be as reliable as the analysis of in-vitro activity of PEP-C in the spring (April). [ABSTRACT FROM PUBLISHER]

This review assesses the impacts, both direct and indirect, of man-made changes to the composition of the air over a 200 year period on the severity of arable crop disease epidemics. The review focuses on two well-studied UK arable crops, wheat and oilseed rape, relating these examples to worldwide food security. In wheat, impacts of changes in concentrations of SO in air on two septoria diseases are discussed using data obtained from historical crop samples and unpublished experimental work. Changes in SO seem to alter septoria disease spectra both through direct effects on infection processes and through indirect effects on soil S status. Work on the oilseed rape diseases phoma stem canker and light leaf spot illustrates indirect impacts of increasing concentrations of greenhouse gases, mediated through climate change. It is projected that, by the 2050s, if diseases are not controlled, climate change will increase yields in Scotland but halve yields in southern England. These projections are discussed in relation to strategies for adaptation to environmental change. Since many strategies take 10-15 years to implement, it is important to take appropriate decisions soon. Furthermore, it is essential to make appropriate investment in collation of long-term data, modelling and experimental work to guide such decision-making by industry and government, as a contribution to worldwide food security. [ABSTRACT FROM AUTHOR]

Abstract: The productivity and diversity of plant communities are affected by soil organisms such as arbuscular mycorrhizal fungi (AMF), root herbivores and decomposers. However, it is unknown how interactions between such functionally dissimilar soil organisms affect plant communities and whether the combined effects are additive or interactive. In a greenhouse experiment we investigated the individual and combined effects of AMF (five Glomus species), root herbivores (wireworms and nematodes) and decomposers (collembolans and enchytraeids) on the productivity and nutrient content of a model grassland plant community as well as on soil microbial biomass and community structure. The effects of the soil organisms on productivity (total plant biomass), total root biomass, grass and forb biomass, and nutrient uptake of the plant community were additive. AMF decreased, decomposers increased and root herbivores had no effect on productivity, but in combination the additive effects canceled each other out. AMF reduced total root biomass by 18%, but decomposers increased it by 25%, leading to no net effect on total root biomass in the combined treatments. Total shoot biomass was reduced by 14% by root herbivores and affected by an interaction between AMF and decomposers where decomposers had a positive impact on shoot growth only in presence of AMF. AMF increased the shoot biomass of forbs, but reduced the shoot biomass of grasses, while root herbivores only reduced the shoot biomass of grasses. Interactive effects of the soil organisms were detected on the shoot biomasses of Lotus corniculatus, Plantago lanceolata, and Agrostis capillaris. The C/N ratio of the plant community was affected by AMF. In soil, AMF promoted abundances of bacterial, actinomycete, saprophytic and AMF fatty acid markers. Decomposers alone decreased bacterial and actinomycete fatty acids abundances but when decomposers were interacting with herbivores those abundances were increased. Our results suggests that at higher resolutions, i.e. on the levels of individual plant species and the microbial community, interactive effects are common but do not affect the overall productivity and nutrient uptake of a grassland plant community, which is mainly affected by additive effects of functionally dissimilar soil organisms. [Copyright &y& Elsevier]

Since the industrial revolution there was an increase in the atmospheric greenhouse gases, such as the carbon dioxide (CO2), which may lead to an increase in global temperature by the end of the 21th century. The direct effect of the increase in the CO2 concentration on plants is the possibility of increasing plant growth rate and crop yield, once CO2 is the substrate for photosynthesis. If the increase in CO2 concentration will be accompanied by an increase in air temperature, there may not be an increase in plant growth and crop yield because of a shortening of the developmental cycle an increase in plant tissue respiration. However, the response to elevated CO2 and temperature varies depends upon the crop. Thus, the objective of this review is to assemble information about the ecophysiological response of rice crop, one of the tree major cereals produced and consumed by the world population, to climate change. Plants with the C3 metabolism, as rice, are more benefitted from the increase in atmospheric CO2 oncentration than plants with the C4 metabolism. High daytime and nighttime temperatures may drastically reduce the yield potential of rice crop due to shortening of the developmental cycle and spikelet sterility. Such a trend can be mitigated by selecting genotypes more resistant to conditions of high air temperature during flowering and by changing the sowing date. [ABSTRACT FROM AUTHOR]

A method for evaluating the resistance to leaf mold on Solanum plants was developed using conidial suspensions of Passalora fulva. Moneymaker cultivar and four Near Isogenic Lines (NILs), Cf- Ecp1, Cf-Ecp2, Cf-Ecp4 and Cf-Ecp5 were tested in a greenhouse. The inoculum was adjusted to 105 UFC.mL-1 and applied to the lower leaves. The plants were daily evaluated after inoculation up to 21 days. A standardized scale of leaf symptoms ensured consistency between evaluators. The genotypes, except Cf-Ecp1, Cf-Ecp2, Cf-Ecp4 and Cf-Ecp5 NILs, showed a similar response to P. fulva in natural conditions. The resistance expressed in its NILs was characterized by a hypersensible reaction. Artificial inoculation of plants was an easy, rapid and practicable method to determine resistance to P. fulva. An inoculum adjusted to an appropriate concentration gave uniform symptoms on the inoculated leaves. The method used proved to be a promissory tool for the evaluation of tomato genotype response in breeding programmes. [ABSTRACT FROM AUTHOR]

Abstract: Increasing atmospheric greenhouse gas concentrations are expected to induce significant climate change over the next century and beyond, but the impacts on society remain highly uncertain. This work examines potential climate change impacts on the productivity of five major crops in eastern China: canola, corn, potato, rice, and winter wheat. In addition to determining domain-wide trends, the objective is to identify vulnerable and emergent regions under future climate conditions, defined as having a greater than 10% decrease and increase in productivity, respectively. Data from the ICTP RegCM3 regional climate model for baseline (1961–1990) and future (2071–2100) periods under A2 scenario conditions are used as input for the EPIC agro-ecosystem simulation model in the domain [30°N, 108°E] to [42°N, 123°E]. Simulations are performed with and without the enhanced CO2-fertilization effect. Results indicate that aggregate potential productivity (i.e. if the crop is grown everywhere) increases 6.5% for rice, 8.3% for canola, 18.6% for corn, 22.9% for potato, and 24.9% for winter wheat, although with significant spatial variability for each crop. However, without the enhanced CO2-fertilization effect, potential productivity declines in all cases ranging from 2.5 to 12%. Interannual yield variability remains constant or declines in all cases except rice. Climate variables are found to be more significant drivers of simulated yield changes than changes in soil properties, except in the case of potato production in the northwest where the effects of wind erosion are more significant. Overall, in the future period corn and winter wheat benefit significantly in the North China Plain, rice remains dominant in the southeast and emerges in the northeast, potato and corn yields become viable in the northwest, and potato yields suffer in the southwest with no other crop emerging as a clear beneficiary from among those simulated in this study. [Copyright &y& Elsevier]

Greenhouse experiments were conducted to assess the effects of salinization of soil on emergence, seedling growth, and mineral accumulation of Prosopis cineraria (Linn.) Druce (Mimosaceae). A mixture of chlorides and sulfates of sodium (Na), potassium (K), calcium (Ca), and magnesium (Mg) was added to the soil and salinity was maintained at 5.1, 7.2, 9.3, 11.5, and 13.3 dS m -1 . A negative relationship between seedling emergence and salt concentration was obtained. Seedlings did not emerge when soil salinity exceeded 11.5 dS m -1 . Results suggested that this tree species is salt tolerant at seed germination and seedling stages. Elongation of stem and root was retarded by increasing salt stress. Young roots and stem were most tolerant to salt stress, followed by old roots and leaves. Leaf tissue exhibited maximum reduction in dry-mass production in response to increasing salt stress. However, production of young roots and death of old roots were found to be continuous and plants apparently use this process as an avoidance mechanism to remove excess ions and delay onset of ion accumulation in this tissue. Plants accumulated Na in roots and were able to regulate transfer of Na ions to leaves. Stem tissues were a barrier for translocation of Na from root to leaf. Moreover, K decreased in root tissues with increased salinization. Nitrogen (N) content significantly ( P [ABSTRACT FROM AUTHOR]

Intensive dairy farming systems are a large source of emission of the greenhouse gas nitrous oxide (N2O), because of high nitrogen (N) application rates to grasslands and silage maize fields. The objective of this study was to compare measured N2O emissions from two different soils to default N2O emission factors, and to look at alternative emission factors based on (i) the N uptake in the crop and (ii) the N surplus of the system, i.e., N applied minus N uptake by the crop. Twelve N fertilization regimes were implemented on a sandy soil (typic endoaquoll) and a clay soil (typic endoaquept) in the Netherlands, and N2O emissions were measured throughout the growing season. Highest cumulative fluxes of 1.92 and 6.81 kg N2O-N ha-1 for the sandy soil and clay soil were measured at the highest slurry application rate of 250 kg N ha-1. Background emissions from unfertilized soils were 0.14 and 1.52 kg N2O-N ha-1 for the sandy soil and the clay soil, respectively. Emission factors for the sandy soil averaged 0.08, 0.51 and 0.26% of the N applied via fertilizer, slurry, and combinations of both. For the clay soil, these numbers were 1.18, 1.21 and 1.69%, respectively. Surplus N was linearly related to N2O emission for both the sandy soil (R2=0.60) and the clay soil (R2=0.40), indicating a possible alternative emission factor. We concluded that, in our study, N2O emission was not linearly related to N application rates, and varied with type and application rate of fertilizer. Finally, the relatively high emission from the clay soil indicates that background emissions might have to be taken into account in N2O budgets. [ABSTRACT FROM AUTHOR]