1,720,974 research outputs found
Cultivar-Dependent Responses in Plant Growth, Leaf Physiology, Phosphorus Use Efficiency, and Tuber Quality of Potatoes Under Limited Phosphorus Availability Conditions
No full textThe limited availability of phosphorus (P) in soils causes a major constraint in the productivity of potatoes, which requires increased knowledge of plant adaptation responses in this condition. In this study, six potato cultivars, namely, Agria, Lady Claire, Milva, Lilly, Sieglinde, and Verdi, were assessed for their responses on plant growth, leaf physiology, P use efficiency (PUE), and tuber quality with three P levels (P low , P med , and P high ). The results reveal a significant variation in the cultivars in response to different P availabilities. P-efficient cultivars, Agria, Milva, and Lilly, possessed substantial plant biomass, tuber yield, and high P uptake efficiency (PUpE) under low P supply conditions. The P-inefficient cultivars, Lady Claire, Sieglinde, and Verdi, could not produce tubers under P deprivation conditions, as well as the ability to efficiently uptake P under low-level conditions, but they were efficient in P uptake under high soil P conditions. Improved PUpE is important for plant tolerance with limited P availability, which results in the efficient use of the applied P. At the leaf level, increased accumulations of nitrate, sulfate, sucrose, and proline are necessary for a plant to acclimate to P deficiency-induced stress and to mobilize leaf inorganic phosphate to increase internal PUE and photosynthesis. The reduction in plant biomass and tuber yield under P-deficient conditions could be caused by reduced CO 2 assimilation. Furthermore, P deficiency significantly reduced tuber yield, dry matter, and starch concentration in Agria, Milva, and Lilly. However, contents of tuber protein, sugars, and minerals, as well as antioxidant capacity, were enhanced under these conditions in these cultivars. These results highlight the important traits contributing to potato plant tolerance under P-deficient conditions and indicate an opportunity to improve the P efficiency and tuber quality of potatoes under deficient conditions using more efficient cultivars. Future research to evaluate molecular mechanisms related to P and sucrose translocation, and minimize tuber yield reduction under limited P availability conditions is necessary.The limited availability of phosphorus (P) in soils causes a major constraint in the productivity of potatoes, which requires increased knowledge of plant adaptation responses in this condition. In this study, six potato cultivars, namely, Agria, Lady Claire, Milva, Lilly, Sieglinde, and Verdi, were assessed for their responses on plant growth, leaf physiology, P use efficiency (PUE), and tuber quality with three P levels (P low , P med , and P high ). The results reveal a significant variation in the cultivars in response to different P availabilities. P-efficient cultivars, Agria, Milva, and Lilly, possessed substantial plant biomass, tuber yield, and high P uptake efficiency (PUpE) under low P supply conditions. The P-inefficient cultivars, Lady Claire, Sieglinde, and Verdi, could not produce tubers under P deprivation conditions, as well as the ability to efficiently uptake P under low-level conditions, but they were efficient in P uptake under high soil P conditions. Improved PUpE is important for plant tolerance with limited P availability, which results in the efficient use of the applied P. At the leaf level, increased accumulations of nitrate, sulfate, sucrose, and proline are necessary for a plant to acclimate to P deficiency-induced stress and to mobilize leaf inorganic phosphate to increase internal PUE and photosynthesis. The reduction in plant biomass and tuber yield under P-deficient conditions could be caused by reduced CO 2 assimilation. Furthermore, P deficiency significantly reduced tuber yield, dry matter, and starch concentration in Agria, Milva, and Lilly. However, contents of tuber protein, sugars, and minerals, as well as antioxidant capacity, were enhanced under these conditions in these cultivars. These results highlight the important traits contributing to potato plant tolerance under P-deficient conditions and indicate an opportunity to improve the P efficiency and tuber quality of potatoes under deficient conditions using more efficient cultivars. Future research to evaluate molecular mechanisms related to P and sucrose translocation, and minimize tuber yield reduction under limited P availability conditions is necessary.Open-Access-Publikationsfonds 202
Long term effects of fire on the soil greenhouse gas balance of an old-growth temperate rainforest
No full textForest fires can cause great changes in the composition, structure and functioning of forest ecosystems. We studied the effects of a fire that occurred >50 years ago in a temperate rainforest that caused flooding conditions in a Placic Andosol to evaluate how long these effects last; we hypothesized that the effects of fire on the soil greenhouse gas (GHG) balance could last for many years. We made monthly measurements of fluxes of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) during two years of soils in an unburned forest (UF) and a nearby site that burned >50 years ago (BS). Our results show that CO2 emissions from soils were higher in the UF than in the BS, and positively correlated with temperature and negatively with soil water content at both sites. Both sites were net CH4 sinks (higher in the UF) and fluxes correlated positively with soil water content and negatively with temperature (stronger relation in the BS). Emissions of N2O were low at both sites and showed correlation with friction velocity at the UF site. The soil GHG balance showed that the UF emitted about 80% more than the BS (5079 ± 1772 and 2815 ± 1447 g CO2-eq m−2 y−1, respectively). Combining our measured fluxes with data of CO2 net ecosystem exchange, we estimated that at the ecosystem level, the UF was a GHG sink while the BS was a source, showing a long-lasting effect of the fire and the importance of preserving these forest ecosystems
El Niño–Southern Oscillation (ENSO) event reduces CO2 uptake of an Indonesian oil palm plantation
No full text<jats:p>Abstract. The El Niño–Southern Oscillation (ENSO) in 2015 was one of the strongest observed in almost 20 years and set the stage for a severe drought and the emergence of widespread fires and related smoke emission over large parts of Southeast Asia. In the tropical lowlands of Sumatra, which were heavily affected by the drought and haze, large areas of tropical rainforest have been converted into oil palm (Elaeis guineensis Jacq.) plantations during the past decades. In this study, we investigate the impact of drought and smoke haze on the net ecosystem CO2 exchange, evapotranspiration, yield and surface energy budget in a commercial oil palm plantation in Jambi province (Sumatra, Indonesia) by using micrometeorological measurements, the eddy covariance method, yield data and a multiple linear regression model (MLRM). With the MLRM we identify the contribution of meteorological and environmental parameters to the net ecosystem CO2 exchange. During the initial part of the drought, when incoming shortwave radiation was elevated, net CO2 uptake increased by 50 % despite a decrease in upper-layer soil moisture by 35 %, an increase in air temperature by 10 % and a tripling of atmospheric vapour pressure deficit. Emerging smoke haze decreased incoming solar radiation by 35 % compared to non-drought conditions and diffuse radiation almost became the sole shortwave radiation flux for 2 months, resulting in a strong decrease in net CO2 uptake by 86 %. Haze conditions resulted in a complete pause of oil palm net carbon accumulation for about 1.5 months and contributed to a decline in oil palm yield by 35 %. With respect to a projected pronounced drying trend over the western Pacific during a future El Niño, our model showed that an increase in drought may stimulate net CO2 uptake, while more severe smoke haze, in combination with drought, can lead to pronounced losses in productivity and net CO2 uptake, highlighting the importance of fire prevention. </jats:p>
The influence of surface roughness and turbulence on heat fluxes from an oil palm plantation in Jambi, Indonesia
No full textOil palm plantations are expanding vastly in Jambi, resulted in altered surface roughness and turbulence characteristics, which may influence exchange of heat and mass. Micrometeorological measurements above oil palm canopy were conducted for the period 2013–2015. The oil palms were 12.5 years old, canopy height 13 meters and 1.5 years old canopy height 2.5 m. We analyzed the influence of surface roughness and turbulence strenght on heat (sensible and latent) fluxes by investigating the profiles and gradient of wind speed, and temperature, surface roughness (roughness length, zo, and zero plane displacement, d), and friction velocity u . Fluxes of heat were calculated using profile similarity methods taking into account atmospheric stability calculated using Richardson number Ri and the generalized stability factor ζ. We found that roughness parameters (zo, d, and u ) directly affect turbulence in oil palm canopy and hence heat fluxes; they are affected by canopy height, wind speed and atmospheric stability. There is a negative trend of d towards air temperature above the oil palm canopy, indicating the effect of plant volume and height in lowering air temperature. We propose studying the relation between zero plane displacement d with a remote sensing vegetation index for scaling up this point based analysis
Expansion of oil palm and other cash crops causes an increase of the land surface temperature in the Jambi province in Indonesia
Full text linkIndonesia is currently one of the regions with the highest transformation rate of land surface worldwide related to the expansion of oil palm plantations and other cash crops replacing forests on large scales. Land cover changes, which modify land surface properties, have a direct effect on the land surface temperature (LST), a key driver for many ecological functions. Despite the large historic land transformation in Indonesia toward oil palm and other cash crops and governmental plans for future expansion, this is the first study so far to quantify the impacts of land transformation on the LST in Indonesia. We analyze LST from the thermal band of a Landsat image and produce a high-resolution surface temperature map (30 m) for the lowlands of the Jambi province in Sumatra (Indonesia), a region which suffered large land transformation towards oil palm and other cash crops over the past decades. The comparison of LST, albedo, normalized differenced vegetation index (NDVI) and evapotranspiration (ET) between seven different land cover types (forest, urban areas, clear-cut land, young and mature oil palm plantations, acacia and rubber plantations) shows that forests have lower surface temperatures than the other land cover types, indicating a local warming effect after forest conversion. LST differences were up to 10.1 ± 2.6 °C (mean ± SD) between forest and clear-cut land. The differences in surface temperatures are explained by an evaporative cooling effect, which offsets the albedo warming effect. Our analysis of the LST trend of the past 16 years based on MODIS data shows that the average daytime surface temperature in the Jambi province increased by 1.05 °C, which followed the trend of observed land cover changes and exceeded the effects of climate warming. This study provides evidence that the expansion of oil palm plantations and other cash crops leads to changes in biophysical variables, warming the land surface and thus enhancing the increase of the air temperature because of climate change
Oil palm plantations are large sources of nitrous oxide, but where are the data to quantify the impact on global warming?
Full text linkOil palm plantations have rapidly expanded over the last 30 years, and now occupy 10% of the world’s permanent cropland. The growth of one of the world’s most efficient and versatile crop has alleviated poverty and increased food and energy security, but not without side effects. Losses of forest biodiversity hits the news. Although equally important, climate change issues have not reached this limelight. Data on greenhouse gas emissions associated with oil palm production is limited, especially for the potent greenhouse gas nitrous oxide (N2O). This paper provides an overview of the data availability, and identifies knowledge gaps to steer future research to provide the data required for climate change models and more accurate international and national nitrous oxide emission accounting
Nitrogen oxide emissions from an irrigated maize crop amended with treated pig slurries and composts in a Mediterranean climate
No full text12 Páginas, 6 figuras y 7 tablas estadísticasOrganic fertilizers may differ greatly in composition and as a result there may also be differences in nitrogen oxides emissions following
their application to soils. The aim of this study was to evaluate the influence of mineral and organic N fertilizers on the nitrification and
denitrification processes, and consequently on N2O and NO emissions. Therefore, a field experiment was carried out on an irrigated sandy
loam soil under Mediterranean conditions during the maize (Zea mays L.) growing season. Untreated pig slurry (UPS) both with and without
the nitrification inhibitor dicyandiamide (UPS + DCD), digested thin pig slurry fraction (DTP), composted solid fraction of slurry mixed with
urea (CPS + U) and composted municipal solid waste mixed with urea (MSW + U) were applied at a rate of 175 kg available N ha 1. Their
emissions were compared with those from urea (U) and a control treatment to which no nitrogen fertilization was administered (Control).
Accumulated nitrous oxide losses during the crop season ranged from 6.0 to 9.3 kg N2O-N ha 1 for the Control and CPS + U, respectively,
whereas nitric oxide losses ranged from 0.01 to 0.23 kg NO-N ha 1, for the Control and U, respectively. The use of digested slurries mitigated
N2O emission by 25% in relation to untreated pig slurry, but NO emissions were similar for both treatments. Dicyandiamide reduced N2O and
NO emissions by 64 and 78% with respect to slurry without the inhibitor. An indirect effect of DCD on denitrification was also observed, with
a reduction of 32% in denitrification with respect to the slurry without the inhibitor. In this case, the greatest reduction in denitrification losses
occurred during the irrigation period. Composts mixed with urea reduced NO emissions by 56% (CPS + U) and 85% (MSW + U) in relation to
the urea treatment, but its effect on N2O depended on the type of compost involved: CPS + U increased N2O emission by 27%, whereas
MSW + U reduced it by 55% in relation to urea. Denitrification was the most important process responsible for N2O emissions when organic
fertilizers were applied to the soil, while nitrification was the most important for the inorganic fertilizer. The C:N ratio of fertilizers was a good
predictor of their NO emissions, denitrification losses and N2O/N2 ratio. On the other hand, added soluble N was a good predictor for
cumulative N2O emissions during the period before irrigation. This work shows that an appropriate selection of organic fertilizers based on
their composition could be used to mitigate emissions of the atmospheric pollutants NO and N2O in comparison with urea.Peer reviewe
Measured greenhouse gas budgets challenge emission savings from palm-oil biodiesel
No full textThe potential of palm-oil biofuels to reduce greenhouse gas (GHG) emissions compared with fossil fuels is increasingly questioned. So far, no measurement-based GHG budgets were available, and plantation age was ignored in Life Cycle Analyses (LCA). Here, we conduct LCA based on measured CO2, CH4 and N2O fluxes in young and mature Indonesian oil palm plantations. CO2 dominates the on-site GHG budgets. The young plantation is a carbon source (1012 ± 51 gC m−2 yr−1), the mature plantation a sink (−754 ± 38 gC m−2 yr−1). LCA considering the measured fluxes shows higher GHG emissions for palm-oil biodiesel than traditional LCA assuming carbon neutrality. Plantation rotation-cycle extension and earlier-yielding varieties potentially decrease GHG emissions. Due to the high emissions associated with forest conversion to oil palm, our results indicate that only biodiesel from second rotation-cycle plantations or plantations established on degraded land has the potential for pronounced GHG emission savings
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