Investigating the effect of previous treatments on wheat biomass over multiple spatial frequencies

Abstract. In this study we use the maximum overlap discrete packet transform (MODWPT) to investigate residual effects on wheat biomass of fertigation treatments applied to a previous crop. The wheat crop covered nine subplots from a previous experiment on melon response to fertigation. Each subplot had previously received a different level of applied nitrogen. Many factors affect wheat biomass, causing it to vary at different spatial frequencies. We hypothesize that these will include residual effects from fertilizer application (at relatively low spatial frequencies) and the local influence of individual plants from the previous melon crop (at high frequency). To test this hypothesis we use the MODWPT to identify the dominant spatial frequencies of wheat biomass variation, and analyse the relationship to both the previous fertilizer application and the location of individual melon plants in the previous crop. The MODWPT is particularly appropriate for this because it allows us first to identify the key spatial frequencies in the wheat biomass objectively and to analyse them, and their relationship to hypothesized driving factors without any assumptions of uniformity (stationarity) of wheat-biomass variation. The results showed that the applied nitrogen dominated the wheat biomass response, and that there was a noticeable component of wheat-biomass variation at the spatial frequency that corresponds to the melon cropping. We expected wheat biomass to be negatively correlated with the position of melons in the previous crop, due to uptake of the applied nitrogen. The MODWPT, which allows us to detect changes in correlation between variables at different frequencies, showed that such a relationship was found across part of the experiment but not uniformly.

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Scale and space dependencies of soil Nitrogen variability

10.5194/npg-2016-32 ◽

2016 ◽

Author(s):

Ana M. Tarquis ◽

María Teresa Castellanos ◽

Maria Carmen Cartagena ◽

Augusto Arce ◽

Francisco Ribas ◽

...

Keyword(s):

Nitrogen Content ◽

Scaling Behavior ◽

Residual Effects ◽

Wheat Crop ◽

Structure Variation ◽

Previous Crop ◽

Whole Plant ◽

Grain Nitrogen ◽

Generalized Dimensions ◽

Applied Nitrogen

Abstract. In this study we use the multifractal analysis, through generalized dimensions (Dq) and the relative entropy (E(δ)) to investigate residual effects on wheat and grain, biomass and nitrogen content, of fertigation treatments applied to a previous crop. The wheat crop covered nine subplots from a previous experiment on melon response to fertigation. Each subplot had previously received a different level of applied nitrogen and plants from the previous melon crop had already taken up part of it. Many factors affect these variables, causing it to vary at different scales creating a non uniform distribution. The Dq were used to study the relation between scales meanwhile E(δ), and their increments between scales, were used to identify the scale at which the variable had a maximum structure and compare with the scaling behavior of the nitrogen applied. The E(δ) is particularly appropriate for this because of does not require any prior assumptions to the structure of the data and it is easy to calculate. The four variables studied presented a weak multifractal character presenting a low variation in Dq values, around the unit, that wasn't relevant for the study. On the other hand, the E(δ) and the increments in E(δ) help us to detect changes in the scaling behavior of all the variables studied. To this respect, the results showed that the applied nitrogen through fertirrigation dominated the wheat and grain biomass response as well as nitrogen content of the whole plant; surprisingly grain nitrogen content didn't show the same structure than the applied nitrogen. At the same time, there was a noticeable structure variation in the biomass and nitrogen content at the smaller scales that correspond to the previous cropping root arrangement due to uptake of the applied nitrogen.

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Residual effects of phosphorus and soyabean crop on maize in the Guinea savanna of West Africa

Acta Agronomica Hungarica ◽

10.1556/aagr.57.2009.1.10 ◽

2009 ◽

Vol 57 (1) ◽

pp. 87-94

Author(s):

I. Ogoke ◽

A. Togun

Keyword(s):

Dry Matter ◽

Fertilizer Application ◽

Residual Effects ◽

Available P ◽

Triple Superphosphate ◽

Guinea Savanna ◽

Previous Crop ◽

P Rate ◽

P Application ◽

Total Soil N

Two seasons of cropping were carried out at three sites in the Guinea savanna to evaluate the residual effects of soyabean on maize. The experiment was laid out as a splitplot design in a randomized complete block with three replications. In the first season, four soyabean varieties with a fallow treatment (control) received phosphorus (P) applied as triple superphosphate (20% P) at the rates of 30 and 60 kg P ha −1 . Maize was grown in these plots in the second season without fertilizer application. At all sites, regardless of the previous crop, total soil N remained low (<1.5 g kg −1 ). Available P was affected by the P rate in the previous year at all sites. From initial values ranging from 5.2–16.2 mg kg −1 in the first season, available P significantly (p<0.05) increased in the second season to 9.8–42.8 mg kg −1 when 30 or 60 kg P ha −1 was applied, compared to 7.7–18.6 mg kg –1 at no P application. Relative to no P application in the previous year, the application of 60 kg P ha −1 significantly increased total dry matter at 6 weeks after planting by 19%, total harvest dry matter by 28%, and grain yield by 37%.

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Disparity Modulation Sensitivity for Narrow-Band-Filtered Stereograms Viewed out of the Plane of Fixation

Perception ◽

10.1068/v96p0206 ◽

1996 ◽

Vol 25 (1_suppl) ◽

pp. 94-94

Author(s):

B Lee ◽

B J Rogers

Keyword(s):

Spatial Frequency ◽

High Frequency ◽

Significant Interaction ◽

Narrow Band ◽

Low Frequency ◽

Frequency Pattern ◽

Spatial Frequencies ◽

Size Disparity ◽

Random Dot Stereograms

Narrow-band-filtered random-dot stereograms were used to determine stereo thresholds for detecting sinusoidal disparity modulations. These stereograms were designed to stimulate selectively channels tuned to luminance and corrugation spatial frequencies (Schumer and Ganz, 1979 Vision Research19 1303 – 1314). Thresholds were determined for corrugation frequencies ranging from 0.125 to 1 cycle deg−1, luminance centre spatial frequencies ranging from 1 to 8 cycles deg−1 and disparity pedestal sizes ranging from −32 to +32 min arc. For small disparity pedestals, lowest modulation thresholds were found around 0.5 cycle deg−1 corrugation frequency and 4 cycles deg−1 luminance centre spatial frequency. For large disparity pedestals (±32 arc min), lowest thresholds were shifted towards the lower corrugation frequencies (0.125 cycle deg−1) and lower luminance frequencies (2 cycles deg−1). There was a significant interaction between luminance spatial frequency and disparity pedestal size. For small pedestals, lowest thresholds were found with the highest luminance frequency pattern (4 cycles deg−1). For large pedestals, best performance shifted towards the low-frequency patterns (1 cycle deg−1). This effect demonstrates a massive reduction in stereo-efficiency for high-frequency patterns in the luminance domain at large disparity pedestals which is consistent with the ‘size-disparity relation’ proposed by previous researchers.

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Spatial Scale Interactions and Visual-Tracking Performance

Perception ◽

10.1068/p261047 ◽

1997 ◽

Vol 26 (8) ◽

pp. 1047-1058 ◽

Cited By ~ 1

Author(s):

Howard C Hughes ◽

David M Aronchick ◽

Michael D Nelson

Keyword(s):

Spatial Frequency ◽

High Frequency ◽

Visual Information ◽

Low Frequency ◽

High Spatial Frequency ◽

Performance Measure ◽

High Frequency Component ◽

Stimulus Velocity ◽

Spatial Frequencies ◽

Wide Range

It has previously been observed that low spatial frequencies (≤ 1.0 cycles deg−1) tend to dominate high spatial frequencies (≥ 5.0 cycles deg−1) in several types of visual-information-processing tasks. This earlier work employed reaction times as the primary performance measure and the present experiments address the possibility of low-frequency dominance by evaluating visually guided performance of a completely different response system: the control of slow-pursuit eye movements. Slow-pursuit gains (eye velocity/stimulus velocity) were obtained while observers attempted to track the motion of a sine-wave grating. The drifting gratings were presented on three types of background: a uniform background, a background consisting of a stationary grating, or a flickering background. Low-frequency dominance was evident over a wide range of velocities, in that a stationary high-frequency component produced little disruption in the pursuit of a drifting low spatial frequency, but a stationary low frequency interfered substantially with the tracking of a moving high spatial frequency. Pursuit was unaffected by temporal modulation of the background, suggesting that these effects are due to the spatial characteristics of the stationary grating. Similar asymmetries were observed with respect to the stability of fixation: active fixation was less stable in the presence of a drifting low frequency than in the presence of a drifting high frequency.

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The relationship between evapotranspiration and growth in the wheat crop

Australian Journal of Agricultural Research ◽

10.1071/ar9660255 ◽

1966 ◽

Vol 17 (3) ◽

pp. 255 ◽

Cited By ~ 21

Author(s):

RA Fischer ◽

GD Kohn

Keyword(s):

Soil Moisture ◽

Vegetative Growth ◽

Dry Weight ◽

Fertilizer Application ◽

Wheat Crop ◽

South Wales ◽

Evapotranspiration Rate ◽

Total Dry Weight ◽

Delayed Flowering ◽

The Relationship

In trials conducted in 1961 and 1962 at Wagga in southern New South Wales, to investigate the yield physiology of wheat, the variety Heron was grown under various cultural treatments. This paper deals with the relationship of evapotranspiration to crop growth. Vegetative growth at a given date in the spring was influenced markedly by time of sowing and fertilizer application, and to a lesser extent by sowing rate. Large differences in vegetative growth caused relatively small differences in evapotranspiration rate when soil moisture was adequate. An increase in total dry weight of 100 g/m² in early October was associated with an increase in cumulative evapotranspiration up to that time of about 0.50 in. It was concluded that although a reduced fertilizer application and reduced sowing rate (below 3b lb seed per acre) permitted higher soil moisture levels at flowering, this necessarily involved a considerable reduction in total dry weight at flowering. With delayed time of sowing, the post-flowering moisture status of the crop can be expected to deteriorate, primarily because of delayed flowering date.

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Effect of repetitive visual stimuli on behaviour and plasma corticosterone of European starlings

Animal Biology ◽

10.1163/1570756054472827 ◽

2005 ◽

Vol 55 (3) ◽

pp. 245-258 ◽

Cited By ~ 3

Author(s):

◽

Keyword(s):

Spatial Frequency ◽

High Frequency ◽

Temporal Frequency ◽

Low Frequency ◽

High Spatial Frequency ◽

Plasma Corticosterone ◽

European Starlings ◽

Fluorescent Lamps ◽

Spatial Frequencies ◽

Temporal And Spatial

AbstractFlickering light can cause adverse effects in some humans, as can rhythmic spatial patterns of particular frequencies. We investigated whether birds react to the temporal frequency of standard 100 Hz fluorescent lamps and the spatial frequency of the visual surround in the manner predicted by the human literature, by examining their effects on the preferences, behaviour and plasma corticosterone of European starlings (Sturnus vulgaris). We predicted that high frequency lighting (> 30 kHz) and a relatively low spatial frequency on the walls of their cages (0.1 cycle cm−1) would be less aversive than low frequency lighting (100 Hz) and a relatively high spatial frequency (2.5 cycle cm−1). Birds had strong preferences for both temporal and spatial frequencies. These preferences did not always fit with predictions, although there was evidence that 100 Hz was more stressful than 30 kHz lighting, as birds were less active and basal corticosterone levels were higher under 100 Hz lighting. Our chosen spatial frequencies had no overall significant effect on corticosterone levels. Although there are clearly effects of, and interactions between, the frequency of the light and the visual surround on the behaviour and physiology of birds, the pattern of results is not straightforward.

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Global Precedence, Spatial Frequency Channels, and the Statistics of Natural Images

Journal of Cognitive Neuroscience ◽

10.1162/jocn.1996.8.3.197 ◽

1996 ◽

Vol 8 (3) ◽

pp. 197-230 ◽

Cited By ~ 168

Author(s):

Howard C. Hughes ◽

George Nozawa ◽

Frederick Kitterle

Keyword(s):

Spatial Frequency ◽

High Frequency ◽

Reaction Times ◽

Low Frequency ◽

Natural Images ◽

Visual Pattern ◽

Pattern Perception ◽

Global Precedence ◽

Processing Times ◽

Spatial Frequencies

A great deal of evidence suggests that early in processing, retinal images are filtered by parallel, spatial frequency selective channels. We attempt to incorporate this view of early vision with the principle of global precedence, which holds that Gestalt-like processes sensitive to global image configurations tend to dominate local feature processing in human pattern perception. Global precedence is inferred from the pattern of reaction times observed when visual patterns contain multiple cues at different levels of spatial scale. Specifically, it is frequently observed that global processing times are largely unaffected by conflicting local cues, but local processing times are substantially lengthened by conflicting global cues. The asymmetry of these effects suggests the dominant role of global configurations. Since global spatial information is effectively represented by low spatial frequencies, global precedence potentially implies a low frequency dominance. The thesis is that low spatial frequencies tend to be available before information carried by higher frequency bands, producing a coarse-to-fine temporal order in visual spatial perception. It is suggested that a variety of factors contribute to the “prior entry” of low frequency information, including the high contrast gain of the magnocellular pathway, the amplitude spectra typical of natural images, and inhibitory interactions between the parallel frequency-tuned channels. Evidence suggesting a close relationship between global precedence and spatial frequency channels is provided by observations that the essential features of the global precedence effect are obtained using patterns consisting of low and high frequency sinusoids. The hypothesis that these asymmetric interference effects are due to interactions between parallel spatial channels is supported by an analysis of reaction times (RTs), which shows that RTs to redundant low and high frequency cues produce less facilitation than predictions that assume the channels are independent. In view of previous work showing that global precedence depends upon the low frequency content of the stimuli, we suggest that low spatial frequencies represent the sine qua non for the dominance of configurational cues in human pattern perception, and that this configurational dominance reflects the microgenesis of visual pattern perception. This general view of the temporal dynamics of visual pattern recognition is discussed, is considered from an evolutionary perspective, and is related to certain statistical regularities in natural scenes. Potential adaptive advantages of an interactive parallel architecture that confers an initial processing advantage to low resolution information are explored.

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Scale and space dependencies of soil nitrogen variability

Nonlinear Processes in Geophysics ◽

10.5194/npg-24-77-2017 ◽

2017 ◽

Vol 24 (1) ◽

pp. 77-87 ◽

Cited By ~ 4

Author(s):

Ana M. Tarquis ◽

María Teresa Castellanos ◽

Maria Carmen Cartagena ◽

Augusto Arce ◽

Francisco Ribas ◽

...

Keyword(s):

Nitrogen Content ◽

Residual Effects ◽

Wheat Crop ◽

Structure Variation ◽

Scaling Behaviour ◽

Previous Crop ◽

Whole Plant ◽

High Volatility ◽

Grain Nitrogen ◽

Generalized Dimensions

Abstract. In this study, we use multifractal analysis, through generalized dimensions (Dq) and the relative entropy (E(δ)), to investigate the residual effects of fertigation treatments applied to a previous crop on wheat and grain biomass and nitrogen content. The wheat crop covered nine subplots from a previous experiment on melon responses to fertigation. Each subplot had previously received a different level of applied nitrogen (Napp), and the plants from the previous melon crop had already taken up part of it. Many factors affect these variables, causing them to vary at different scales and creating a non-uniform distribution along a transect. Correlations between the four variables and Napp showed high volatility, although the relationships between grain weight and wheat weight versus wheat nitrogen content presented a statistically significant logarithmic trend. The Dq values were used to study the relation between scales and E(δ) values, and their increments between scales were used to identify the scale at which the variable had the maximum structure and were compared with the scaling behaviour of the Napp. E(δ) is particularly appropriate for this purpose because it does not require any prior assumptions regarding the structure of the data and is easy to calculate. The four variables studied presented a weak multifractal character with a low variation in Dq values, although there was a distinction between variables related to nitrogen content and weight. On the other hand, the E(δ) and the increments in E(δ) help us to detect changes in the scaling behaviour of all the variables studied. In this respect, the results showed that the Napp through fertigation dominated the wheat and grain biomass response, as well as the nitrogen content of the whole plant; surprisingly, the grain nitrogen content did not show the same structure as Napp. At the same time, there was a noticeable structure variation in all the variables, except wheat nitrogen content, at smaller scales that could correspond to the previous cropping root arrangement due to uptake of the Napp.

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Investigating the effect of historical treatments on wheat yield over multiple spatial frequencies

Biogeosciences Discussions ◽

10.5194/bgd-7-2143-2010 ◽

2010 ◽

Vol 7 (2) ◽

pp. 2143-2167

Author(s):

A. E. Milne ◽

M. T. Castellanos ◽

M. C. Cartagena ◽

A. M. Tarquis ◽

R. M. Lark

Keyword(s):

Good Reason ◽

Wheat Yield ◽

Frequency Factor ◽

Yield Response ◽

Wheat Crop ◽

Available Nitrogen ◽

Yield Variation ◽

Spatial Frequencies ◽

The Impact ◽

Applied Nitrogen

Abstract. In this study we use the maximum overlap discrete packet transform (MODWPT) to investigate the impact of historical fertirrigation treatments and cropping on wheat yield. Our objective was to identify the spatial frequencies at which such effects can be detected. Here we consider wheat yield data harvested in consecutive 0.5 m × 0.5 m-sections along the transect. Prior to the wheat crop, a split plot design experiment had been done to investigate the effect of different fertirrigation treatments on melon yield. The wheat transect crossed 9 of the subplots from the melon crop experiment. Each subplot had received a different level of applied nitrogen. The melons were grown at a 1.5 m spacing and will have removed a proportion of the available nitrogen, leaving a soil nitrogen residual. We expect soil properties, such as available nitrogen, to be spatially variable as they result from spatially variable factors operating over multiple orders of spatial frequency. In this example we have good reason to believe this: the applied nitrogen changed from subplot to subplot constituting a low frequency factor, and we expected the removal of nitrogen by the melon crop to be a localized effect in the neighbourhood of the plant therefore constituting a higher frequency factor. We chose to use the MODWPT in this analysis as it is ideally suited to the elucidation of multifrequency processes that are not necessarily stationary in the variance. We show that the applied nitrogen dominates the wheat yield response, and that there is a noticeable contribution to wheat yield variation at the frequency that corresponds to the melon cropping. However the correlation analysis suggests that the relationship between wheat yield and melon positioning is not as straightforward as we might expect and that other influences affect wheat yield variation at this frequency.

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Reliability of the Minimum Masking Level as Outcome Variable in Tinnitus Clinical Research

American Journal of Audiology ◽

10.1044/2020_aja-20-00047 ◽

2020 ◽

Vol 29 (3) ◽

pp. 429-435

Author(s):

Patricia C. Mancini ◽

Richard S. Tyler ◽

Hyung Jin Jun ◽

Tang-Chuan Wang ◽

Helena Ji ◽

...

Keyword(s):

Standard Deviation ◽

High Frequency ◽

Pearson Correlation ◽

Correlation Coefficients ◽

Outcome Variable ◽

Reliable Estimate ◽

Moderate Correlation ◽

Trained Subjects ◽

The Relationship ◽

Minimum Intensity

Purpose The minimum masking level (MML) is the minimum intensity of a stimulus required to just totally mask the tinnitus. Treatments aimed at reducing the tinnitus itself should attempt to measure the magnitude of the tinnitus. The objective of this study was to evaluate the reliability of the MML. Method Sample consisted of 59 tinnitus patients who reported stable tinnitus. We obtained MML measures on two visits, separated by about 2–3 weeks. We used two noise types: speech-shaped noise and high-frequency emphasis noise. We also investigated the relationship between the MML and tinnitus loudness estimates and the Tinnitus Handicap Questionnaire (THQ). Results There were differences across the different noise types. The within-session standard deviation averaged across subjects varied between 1.3 and 1.8 dB. Across the two sessions, the Pearson correlation coefficients, range was r = .84. There was a weak relationship between the dB SL MML and loudness, and between the MML and the THQ. A moderate correlation ( r = .44) was found between the THQ and loudness estimates. Conclusions We conclude that the dB SL MML can be a reliable estimate of tinnitus magnitude, with expected standard deviations in trained subjects of about 1.5 dB. It appears that the dB SL MML and loudness estimates are not closely related.

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