574 research outputs found
Phosphorus application strategies in potato
Phosphorus (P) is an essential element that plays an important role in carbohydrate metabolism and energy transfer systems in all plants. Sufficient P supply is therefore essential for providing adequate food, fibre and fuel for society. In potato, P deficiency reduces yield and tuber number due to reduced radiation interception by the canopy.
Phosphorus is a limited, non-renewable resource. When lost to water bodies, P causes environmental problems such as eutrophication. Potato fields may be a significant contributor to P loads to water due to high P recommendations and a tendency for P leaching in soils where the P sorption/binding capacity is saturated. Efficient use of P in potato cultivation is therefore crucial in order to reduce P consumption and environmental impacts.
The thesis improves the current understanding of potato P requirements as regards optimising P application strategies, use efficiency and potato tuber yield. The results show that split P applications can improve P recovery by 25%, particularly on soils with low P content and low buffering capacity, and can improve physiological P use efficiency (PPUE) where P availability is limiting yield. Irrigation and subsoiling can both significantly improve P recovery, PPUE and yield. Foliar application does not improve PPUE, but can increase P concentration and yield if the plant is supplied with sufficient water. However, foliar P application should not be used as a general strategy, but can be recommended where the soil buffering capacity is extremely high. It is shown in this thesis that many Swedish soils contain sufficient amounts of P to support optimal growth and are no longer responsive to P fertilization. To determine the responsiveness of potato yields to P, data on soil organic material, pH, soil buffering capacity and varietal characteristics are needed, in addition to the amount of P-extractable with ammonium lactate (P-AL value) used in Sweden today. More sophisticated P recommendation models which take these parameters into account are urgently needed. As long as yield effects from P fertilization cannot be predicted, excessive P fertilization will probably continue, resulting in waste of a non-renewable resource, eutrophication of the aquatic environment and reduced farm profits. The findings in this thesis contribute to understanding the complex picture of P acquisition in potato and, hopefully, to more efficient use of the non-renewable P resource
Potato yield and tuber set as affected by phosphorus fertilization
In order to minimize phosphorus (P) leaching from potato cropping systems, P recommendations based on facts regarding the influence on the potato plant is needed. A literature study and a practical experiment were conducted in order to determine potato yield and tuber set as affected by Pfertilization. The influence of soil moisture on P availability and the effects of foliarâ P application were also investigated. Five different nutrient P treatments ranging from 0 to 0.3 g/pot were evaluated. Each nutrient P treatment was divided into 8 doses and applied weekly to plantlets grown in 50% pumice stoneâ 50% peat. Two different soil moisture levels were tested, "moist treatment" ranging from 0.35 to 0.45 g cmâ3 and "dry treatment" ranging from 0.25 to 0.35 g cmâ3. Foliarâ P applications were applied 16 and 26 days after emergence (d.a.e.) in line with common practice recommendations. Nutrient P treatments significantly effected the total fresh weight of tubers, shoots and tuber number. The moist treatment gave significant higher yield of both tubers and tuber number compared to the dry treatment which could beexplained by an increased P uptake. The foliarâ P application resulted in higher tuber yield only in plants with low P status within the moist treatment; indicating that plant water and P status might be important for P uptake through leaves. The foliarâ P applications however, gave no significant effects on tuber number.I arbetet mot ett minskat forsforutslĂ€pp frĂ„n Sveriges potatisodlingar krĂ€vs
grundlÀggande kunskaper om fosforns inverkan pÄ potatisplantan för att korrekta
rekommendationer skall kunna ges till vÄra odlare. I detta arbete som innefattar
bÄde en litteraturstudie och ett praktiskt odlingsförsök har fosforns inverkan pÄ
knölsĂ€ttning och skörd studerats i detalj. Ăven markfuktens inverkan pĂ„ fosforns
tillgÀnglighet och bladgödslingens effekt pÄ potatisplantan har studerats. I försöket
som Àr utfört i artificiella vÀxtkammare har fem fosforgivor som varierar mellan 0
och 0,3 g fosfor per kruka testats. Varje behandling delades upp i 8 givor och
tillfördes en gÄng i veckan till varje individuell planta som var planterad i ett
substrat som bestod av 50% pimpsten och 50% torv. TvÄ olika fuktighetsnivÄer
testades, en âfuktig behandlingâ som varierade frĂ„n 0.35 till 0.45 g cmâ3 och en âtorr
behandlingâ som varierade frĂ„n 0.25 till 0.35 g cmâ3. Bladgödslingen utfördes vid tvĂ„
tillfÀllen, första behandlingen gjordes 16 dagar efter uppkomst  och den andra efter
26, helt enligt de rekommendationer som finns. Fosforgivorna pÄverkade bÄde vikt
och knölantal signifikant liksom hög markfukt som gav högre skörd och fler knölar
vilket kunde knytas till ett ökat fosforupptag. Bladgödslingen av fosfor gav en
signifikant skördeökning endast i plantor med lÄg fosforstatus i de fuktiga leden
vilket antyder att plantans vatten och fosforstatus kan vara av betydelse för fosforns
upptag genom bladen. Bladgödslingen resulterade dock inte i fler antal  knölar
Discovery potential for a charged Higgs boson decaying in the chargino-neutralino channel of the ATLAS detector at the LHC
We have investigated charged Higgs boson production via the gluon-bottom
quark mode, gb -> tH+, followed by its decay into a chargino and a neutralino.
The calculations are based on masses and couplings given by the Minimal
Supersymmetric Standard Model (MSSM) for a specific choice of MSSM parameters.
The signature of the signal is characterized by three hard leptons, a
substantial missing transverse energy due to the decay of the neutralino and
the chargino and three hard jets from the hadronic decay of the top quark. The
possibility of detecting the signal over the Standard Model (SM) and non-SM
backgrounds was studied for a set of tanBeta and mA. The existence of 5-sigma
confidence level regions for H+ discovery at integrated luminosities of 100
fb-1 and 300 fb-1 is demonstrated, which cover also the intermediate region 4 <
tanBeta < 10 where H+ decays to SM particles cannot be used for H+ discovery
Study of the Feasibility of an X-Ray Free Electron Laser with a 15 GeV CLIC Beam
This note presents a study of the feasibility of a Free Electron Laser (FEL) using an electron beam from the Compact Linear Collider (CLIC). We first show that, with the nominal CLIC layout, the energy spread at 15 GeV would be too large to allow FEL saturation in an undulator of reasonable length. An alternative scheme was studied, with a dedicated source, with a by-pass of the damping rings and with magnetic compression between the various acceleration stages. With this scheme, the energy spread of the CLIC beam can be reduced from 1.5% to 0.1%, but the emittance is much larger and, although the power gain is better than in the nominal case, FEL saturation is still not reached. We show that the energy spread or the transverse emittance would have to be reduced by another order of magnitude in order to obtain FEL saturation
Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at root s=7 TeV with the ATLAS detector
The inclusive and dijet production cross-sections have been measured for jets containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass energy of root s = 7 TeV, using the ATLAS detector at the LHC. The measurements use data corresponding to an integrated luminosity of 34 pb(-1). The b-jets are identified using either a lifetime-based method, where secondary decay vertices of b-hadrons in jets are reconstructed using information from the tracking detectors, or a muon-based method where the presence of a muon is used to identify semileptonic decays of b-hadrons inside jets. The inclusive b-jet cross-section is measured as a function of transverse momentum in the range 20 < p(T) < 400 GeV and rapidity in the range vertical bar y vertical bar < 2.1. The b<(b)over bar>-dijet cross-section is measured as a function of the dijet invariant mass in the range 110 < m(jj) < 760 GeV, the azimuthal angle difference between the two jets and the angular variable chi in two dijet mass regions. The results are compared with next-to-leading-order QCD predictions. Good agreement is observed between the measured cross-sections and the predictions obtained using POWHEG + Pythia. MC@NLO + Herwig shows good agreement with the measured b (b) over bar -dijet cross-section. However, it does not reproduce the measured inclusive cross-section well, particularly for central b-jets with large transverse momenta.ATLAS Collaboration, for complete list of authors see http://dx.doi.org/10.1140/epjc/s10052-011-1846-4</p
Method for in-field texture analysis of sugar beet roots using a handheld penetrometer
Methodology for analysing textural properties of sugar beet roots in the laboratory has previously been established. It has been shown to be reliable and of value in exploring relationships between textural properties, damage rates, and storability of varieties. In this paper, a methodology for the assessment of textural properties in-field, prior to harvest, using an inexpensive handheld penetrometer is examined. Three sugar beet varieties were grown in Belgium, the Netherlands, and Sweden during 2019. Textural properties were assessed in-field with the handheld penetrometer 2, 1 and 0 months prior to harvest, and with the laboratory penetrometer directly after harvest. Comparison of the results showed generally strong correlations. A power analysis suggests a difference in mean Handheld Pressure of 0.10 MPa could be found significant within a large trial with a block design. The reliability of the handheld penetrometer was further assessed in the Swedish national variety trials over three years (2019-2021). Correlation coefficients of 0.86 and 0.94 were found between mean Handheld Pressure for 2019 and 2020, and 2020 and 2021 respectively. The handheld penetrometer can be applied as an economic means of quantifying differences in textural properties of sugar beet varieties. Clear operating procedure and training must exist
Droppbevattningens inverkan pÄ kvalitet och kvantitet hos Solanum tuberosum L i jÀmförelse med konventionell spridarebevattning
A literature study and a field trial have been carried out in order to investigate the physiological response of potato plants to different soil moisture levels. Higher yield, quality and number of tubers can according to the literature be obtained if constant high soil moisture is kept during major parts of the growing season. A field trial was set up where drip irrigation was used as an alternative to conventional irrigation techniques to maintain high and constant soil moisture. The application of water in the drip irrigated area was monitored and adjusted on a daily basis so that the soil moisture stayed as close as possible to the recommended level. The sprinkle irrigated area was irrigated according to traditional practices with approximately 35 mm every 7th to 10th day depending on the whether. The result from the field trial was in line with the information found in literature; constant high soil moisture gave on average 11 % higher yield, higher quality and higher number of tubers. The marketable yield increased with 28 % in the drip irrigated area compared with the sprinkle irrigated area. The conclusion from this study is that drip irrigation can be used as a cost effective alternative to traditional sprinkle irrigation.En litteraturstudie samt ett fÀltförsök har genomförts för att studera markfuktens inflytande pÄ kvalitet och kvantitet hos Solanum tuberosum. Litteraturstudien visar att hög och jÀmn markfukt vid odling av potatis ger högre skörd, fler antal knölar och bÀttre kvalitet. Ett praktiskt odlingsförsök genomfördes för att undersöka om teorin överenstÀmmer med praktiken. I försöket testades droppbevattning som ett alternativ till konventionell spridarbevattning i ett enkelt blockförsök. Markfukten i det droppbevattnade ledet styrdes utifrÄn avdustningen och reglerades sÄ att den höll sig inom det rekomenderade intervallet. Det spridarbevattnade ledet vattnades pÄ traditionsenligt vis med ca 35 mm var 7-10 dag beroende pÄ vÀderlek. Resultaten frÄn försöket styrkte teorin, en hög och jÀmn markfukt gav i medeltal 11 % högre skörd och den sÀljbara fraktionen, dvs. storleken mellan 38 och 55mm, blev 20 % högre. Största ökningen blev det i fraktionen 38-45 mm dÀr det droppbevattnade ledet gav 36 % mer skörd Àn det spridarbevattnade. I medeltal gav det droppbevattnade ledet 62 % mindre potatis i fraktionen större Àn 55 mm. Andelen foder i det droppbevattnade ledet minskade sÄ att den totala sÀljbara varan ökade med i genomsnitt 28 % i jÀmförelse med det spridarbevattnade ledet. Slutsatsen frÄn denna studie Àr att droppbevattning kan anvÀndas som ett kostnadseffektivt alternativ till spridarbevattning
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