Weed management in coriander (Coriandrum sativum L.) at varying levels of nitrogen

A field experiment was conducted to study the effect of weed control treatments and nitrogen (N) levels on weed dynamics, weed control efficiency, nutrient depletion by weeds, yield of coriander and weed competition index. All the weed control treatments significantly reduced the density and dry weight of weeds and nutrient depletion as compared to weedy check. Oxadiargyl at 0.06 kg ha-1 + hand weeding (HW) at 40 days after sowing (DAS) represented the lowest weed density and controlled the weeds to the extent of 94.9%. Two hand weedings done at 20 and 40 DAS and pendimethalin at 1.0 kg ha-1 + HW at 40 DAS were found to be the most superior treatments in reducing density, intensity and dry weight of weeds and increasing weed control efficiency. These treatments controlled the weeds to the extent of 95.1% and 95.4%, respectively at harvest stage than weedy check and showed lower weed infestation of 17.4 and 18.1%, respectively. The lowest nutrient depletion due to weeds was obtained with pendimethalin at 1.0 kg ha-1 + HW at 40 DAS treatment which saved 54.80 kg N, 8.31 kg P and 49.22 kg K ha-1, respectively than weedy check. Two HWs at 20 and 40 DAS and oxadiargyl at 0.06 kg ha-1 + HW at 40 DAS also reduced the nutrient depletion to the extent of 94.8 and 94.5% of N; 95.0 and 94.7% of P and 94.9 and 94.6% of K, respectively in comparison to weedy check. Two hand weeding treatment gave the highest seed yield (1.37 t ha-1) among all the treatments and was closely followed by pendimethalin at 1.0 kg ha-1 + HW at 40 DAS which also increased the seed yield by a margin of 0.84 t ha-1 over weedy check, and registered the lowest weed competition index of 0.7%. &nbsp

Effect of weed and nitrogen management on coriander (Coriandrum sativum L.) yield and economics

Field experiments were carried out during rabi 2007–08 and 2008–09 to evaluate the effect of different weed management measures and nitrogen (N) application on yield and economics of coriander. Results revealed that two hand weedings (HW) at 20 and 40 days after sowing (DAS) produced the highest seed and straw yields (13.71 and 25.83 q ha-1). The highest net returns (Rs. 55841 ha-1) and B : C ratio (2.39) were also obtained under this treatment. However, it was found to be at par with pendimethalin at 1.0 kg ha-1 + HW at 40 DAS, wherein seed and straw yields of 13.61 and 25.57 q ha-1, respectively were obtained. The highest harvest index of 35.01% as well as the lowest mean weed index of 0.7%, were also observed under pendimethalin at 1.0 kg ha-1 + HW at 40 DAS. Results further revealed that application of N at 75 kg ha-1 significantly increased the seed yield to the extent of 11.9%, 32.7% and 84.3% and net returns by Rs. 7915, Rs. 18366 and Rs. 34536 ha-1 over 50, 25 kg N ha-1 and control, respectively. Correlation studies revealed that seed yield of coriander was significantly and positively correlated with growth and yield attributing characters and nutrient uptake by crop. Based on the response studies, 64.75 kg ha-1 was found to be the optimum level of N for coriander. &nbsp

Open data from the third observing run of LIGO, Virgo, KAGRA and GEO

The global network of gravitational-wave observatories now includes five detectors, namely LIGO Hanford, LIGO Livingston, Virgo, KAGRA, and GEO 600. These detectors collected data during their third observing run, O3, composed of three phases: O3a starting in April of 2019 and lasting six months, O3b starting in November of 2019 and lasting five months, and O3GK starting in April of 2020 and lasting 2 weeks. In this paper we describe these data and various other science products that can be freely accessed through the Gravitational Wave Open Science Center at https://gwosc.org. The main dataset, consisting of the gravitational-wave strain time series that contains the astrophysical signals, is released together with supporting data useful for their analysis and documentation, tutorials, as well as analysis software packages.Comment: 27 pages, 3 figure

Search for subsolar-mass black hole binaries in the second part of Advanced LIGO’s and Advanced Virgo’s third observing run

We describe a search for gravitational waves from compact binaries with at least one component with mass 0.2 M⊙–1.0 M⊙ and mass ratio q ≥ 0.1 in Advanced LIGO and Advanced Virgo data collected between 1 November 2019, 15:00 UTC and 27 March 2020, 17:00 UTC. No signals were detected. The most significant candidate has a false alarm rate of 0.2yr−1 ⁠. We estimate the sensitivity of our search over the entirety of Advanced LIGO’s and Advanced Virgo’s third observing run, and present the most stringent limits to date on the merger rate of binary black holes with at least one subsolar-mass component. We use the upper limits to constrain two fiducial scenarios that could produce subsolar-mass black holes: primordial black holes (PBH) and a model of dissipative dark matter. The PBH model uses recent prescriptions for the merger rate of PBH binaries that include a rate suppression factor to effectively account for PBH early binary disruptions. If the PBHs are monochromatically distributed, we can exclude a dark matter fraction in PBHs fPBH ≳ 0.6 (at 90% confidence) in the probed subsolar-mass range. However, if we allow for broad PBH mass distributions we are unable to rule out fPBH = 1. For the dissipative model, where the dark matter has chemistry that allows a small fraction to cool and collapse into black holes, we find an upper bound fDBH < 10−5 on the fraction of atomic dark matter collapsed into black holes

Model-based cross-correlation search for gravitational waves from the low-mass X-ray binary Scorpius X-1 in LIGO O3 data

We present the results of a model-based search for continuous gravitational waves from the low-mass X-ray binary Scorpius X-1 using LIGO detector data from the third observing run of Advanced LIGO, Advanced Virgo and KAGRA. This is a semicoherent search which uses details of the signal model to coherently combine data separated by less than a specified coherence time, which can be adjusted to balance sensitivity with computing cost. The search covered a range of gravitational-wave frequencies from 25Hz to 1600Hz, as well as ranges in orbital speed, frequency and phase determined from observational constraints. No significant detection candidates were found, and upper limits were set as a function of frequency. The most stringent limits, between 100Hz and 200Hz, correspond to an amplitude h0 of about 1e-25 when marginalized isotropically over the unknown inclination angle of the neutron star's rotation axis, or less than 4e-26 assuming the optimal orientation. The sensitivity of this search is now probing amplitudes predicted by models of torque balance equilibrium. For the usual conservative model assuming accretion at the surface of the neutron star, our isotropically-marginalized upper limits are close to the predicted amplitude from about 70Hz to 100Hz; the limits assuming the neutron star spin is aligned with the most likely orbital angular momentum are below the conservative torque balance predictions from 40Hz to 200Hz. Assuming a broader range of accretion models, our direct limits on gravitational-wave amplitude delve into the relevant parameter space over a wide range of frequencies, to 500Hz or more

Search for Eccentric Black Hole Coalescences during the Third Observing Run of LIGO and Virgo

Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass $M>70$ $M_\odot$) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities $0 < e \leq 0.3$ at $0.33$ Gpc$^{-3}$ yr$^{-1}$ at 90\% confidence level.Comment: 24 pages, 5 figure

Search for subsolar-mass black hole binaries in the second part of Advanced LIGO's and Advanced Virgo's third observing run

We describe a search for gravitational waves from compact binaries with atleast one component with mass 0.2 $M_\odot$ -- $1.0 M_\odot$ and mass ratio $q\geq 0.1$ in Advanced LIGO and Advanced Virgo data collected between 1 November2019, 15:00 UTC and 27 March 2020, 17:00 UTC. No signals were detected. Themost significant candidate has a false alarm rate of 0.2 $\mathrm{yr}^{-1}$. Weestimate the sensitivity of our search over the entirety of Advanced LIGO's andAdvanced Virgo's third observing run, and present the most stringent limits todate on the merger rate of binary black holes with at least one subsolar-masscomponent. We use the upper limits to constrain two fiducial scenarios thatcould produce subsolar-mass black holes: primordial black holes (PBH) and amodel of dissipative dark matter. The PBH model uses recent prescriptions forthe merger rate of PBH binaries that include a rate suppression factor toeffectively account for PBH early binary disruptions. If the PBHs aremonochromatically distributed, we can exclude a dark matter fraction in PBHs$f_\mathrm{PBH} \gtrsim 0.6$ (at 90% confidence) in the probed subsolar-massrange. However, if we allow for broad PBH mass distributions we are unable torule out $f_\mathrm{PBH} = 1$. For the dissipative model, where the dark matterhas chemistry that allows a small fraction to cool and collapse into blackholes, we find an upper bound $f_{\mathrm{DBH}} atomic dark matter collapsed into black holes.<br