scholarly journals Maize Crop Coefficient Estimated from UAV-Measured Multispectral Vegetation Indices

Sensors ◽  
2019 ◽  
Vol 19 (23) ◽  
pp. 5250 ◽  
Author(s):  
Yu Zhang ◽  
Wenting Han ◽  
Xiaotao Niu ◽  
Guang Li
Keyword(s):  
Water Management ◽  
Deficit Irrigation ◽  
Regression Models ◽  
Vegetation Index ◽  
Measurement Data ◽  
Crop Coefficient ◽  
Maize Crop ◽  
Significant Difference ◽  
Farm Scale ◽  
Different Levels

The rapid, accurate, and real-time estimation of crop coefficients at the farm scale is one of the key prerequisites in precision agricultural water management. This study aimed to map the maize crop coefficient (Kc) with improved accuracy under different levels of deficit irrigation. The proposed method for estimating the Kc is based on multispectral images of high spatial resolution taken using an unmanned aerial vehicle (UAV). The analysis was performed on five experimental plots using Kc values measured from the daily soil water balance in Ordos, Inner Mongolia, China. To accurately estimate the Kc, the fraction of vegetation cover (fc) derived from the normalized difference vegetation index (NDVI) was used to compare with field measurements, and the stress coefficients (Ks) calculated from two vegetation index (VI) regression models were compared. The results showed that the NDVI values under different levels of deficit irrigation had no significant difference in the reproductive stage but changed significantly in the maturation stage, with a decrease of 0.09 with 72% water applied difference. The fc calculated from the NDVI had a high correlation with field measurement data, with a coefficient of determination (R2) of 0.93. The ratios of transformed chlorophyll absorption in reflectance index (TCARI) to renormalized difference vegetation index (RDVI) and TCARI to soil-adjusted vegetation index (SAVI) were used, respectively, to establish two types of Ks regression models to retrieve Kc. Compared to the TCARI/SAVI model, the TCARI/RDVI model under different levels of deficit irrigation had better correlation with Kc, with R2 and root-mean-square error (RMSE) values ranging from 0.68 to 0.80 and from 0.140 to 0.232, respectively. Compared to Kc calculated from on-site measurements, the Kc values retrieved from the VI regression models established in this study had greater ability to assess the field variability of soil and crops. Overall, use of the UAV-measured multispectral vegetation index approach could improve water management at the farm scale.

scholarly journals Spatio-temporal variability of biophysical parameters of irrigated maize using orbital remote sensing

2021 ◽  
Vol 42 (4) ◽  
pp. 2181-2202
Author(s):  
Taiara Souza Costa ◽  
◽  
Robson Argolo dos Santos ◽  
Rosângela Leal Santos ◽  
Roberto Filgueiras ◽  
...  
Keyword(s):  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Crop Coefficient ◽  
Coefficient Of Determination ◽  
Landsat 8 ◽  
Crop Evapotranspiration ◽  
Biophysical Parameters ◽  
Planting Dates ◽  
Maize Crop ◽  
Spatio Temporal

This study proposes to estimate the actual crop evapotranspiration, using the SAFER model, as well as calculate the crop coefficient (Kc) as a function of the normalized difference vegetation index (NDVI) and determine the biomass of an irrigated maize crop using images from the Operational Land Imager (OLI) and Thermal Infrared (TIRS) sensors of the Landsat-8 satellite. Pivots 21 to 26 of a commercial farm located in the municipalities of Bom Jesus da Lapa and Serra do Ramalho, west of Bahia State, Brazil, were selected. Sowing dates for each pivot were arranged as North and South or East and West, with cultivation starting firstly in one of the orientations and subsequently in the other. The relationship between NDVI and the Kc values obtained in the FAO-56 report (KcFAO) revealed a high coefficient of determination (R2 = 0.7921), showing that the variance of KcFAO can be explained by NDVI in the maize crop. Considering the center pivots with different planting dates, the crop evapotranspiration (ETc) pixel values ranged from 0.0 to 6.0 mm d-1 during the phenological cycle. The highest values were found at 199 days of the year (DOY), corresponding to around 100 days after sowing (DAS). The lowest BIO values occur at 135 DOY, at around 20 DAS. There is a relationship between ETc and BIO, where the DOY with the highest BIO are equivalent to the days with the highest ETc values. In addition to this relationship, BIO is strongly influenced by soil water availability.

scholarly journals Maize Crop Coefficient Estimation Based on Spectral Vegetation Indices and Vegetation Cover Fraction Derived from UAV-Based Multispectral Images

Agronomy ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 668
Author(s):  
Mariana de Jesús Marcial-Pablo ◽  
Ronald Ernesto Ontiveros-Capurata ◽  
Sergio Iván Jiménez-Jiménez ◽  
Waldo Ojeda-Bustamante
Keyword(s):  
Temporal Resolution ◽  
Vegetation Cover ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Vegetation Indices ◽  
Crop Coefficient ◽  
Irrigation Scheduling ◽  
Multispectral Images ◽  
Maize Crop ◽  
Spectral Models

Remote sensing-based crop monitoring has evolved unprecedentedly to supply multispectral imagery with high spatial-temporal resolution for the assessment of crop evapotranspiration (ETc). Several methodologies have shown a high correlation between the Vegetation Indices (VIs) and the crop coefficient (Kc). This work analyzes the estimation of the crop coefficient (Kc) as a spectral function of the product of two variables: VIs and green vegetation cover fraction (fv). Multispectral images from experimental maize plots were classified to separate pixels into three classes (vegetation, shade and soil) using the OBIA (Object Based Image Analysis) approach. Only vegetation pixels were used to estimate the VIs and fv variables. The spectral Kcfv:VI models were compared with Kc based on Cumulative Growing Degree Days (CGDD) (Kc-cGDD). The maximum average values of Normalized Difference Vegetation Index (NDVI), WDRVI, amd EVI2 indices during the growing season were 0.77, 0.21, and 1.63, respectively. The results showed that the spectral Kcfv:VI model showed a strong linear correlation with Kc-cGDD (R2 > 0.80). The model precision increases with plant densities, and the Kcfv:NDVI with 80,000 plants/ha had the best fitting performance (R2 = 0.94 and RMSE = 0.055). The results indicate that the use of spectral models to estimate Kc based on high spatial and temporal resolution UAV-images, using only green pixels to compute VI and fv crop variables, offers a powerful and simple tool for ETc assessment to support irrigation scheduling in agricultural areas.

scholarly journals A study of agrometeorological parameters for the Kharif maize at Anand (Gujarat)

MAUSAM ◽  
2022 ◽  
Vol 53 (2) ◽  
pp. 127-132
Author(s):  
P. G. THORAT
Keyword(s):  
Regression Models ◽  
Potential Evapotranspiration ◽  
Crop Coefficient ◽  
Maize Crop ◽  
Made In ◽  
Phenological Phases

A study was conducted on the behaviour of evaporation, evapotranspiration and potential evapotranspiration in different phenological phases, during the years 1989, 1990 and 1991 for Kharif Maize crop at Anand (Gujarat).  It has been noticed that evapotranspiration and potential evapotranspiration attained maximum values in grain phase.  In harvesting phase relative evapotranspiration and crop coefficient had lowest values.  The seasonal crop coefficient was obtained 0.84. An attempt has been made in this paper to develop the regression models to estimate potential evapotranspiration and relative evapotranspiration.

Attitudes toward the use of TELL tools in English language learning among Vietnamese Tertiary English majors

2019 ◽  
Vol 5 (5) ◽  
pp. 581-596
Keyword(s):  
Language Learning ◽  
Language Proficiency ◽  
English Language ◽  
English Language Learning ◽  
Guided Learning ◽  
Positive Attitudes ◽  
Significant Difference ◽  
English Majors ◽  
Very High ◽  
Different Levels

Technology plays a crucial role in the self-guided learning of a second language in general and English in particular. Nevertheless, many students in different contexts still ignore the application of technology-enhanced language learning (TELL) tools in enhancing their foreign language proficiency. Therefore, this study is conducted to investigate the attitudes towards the use of TELL tools in English-language learning (ELL) among English majors at one university in Vietnam. To collect data, 197 English majors participated in finishing the questionnaire, and 20 students were invited to join the interviews. The findings are that the majority of students have positive attitudes towards the use of TELL tools and the frequency of using these tools is very high. In addition, the results also reveal that there is no significant difference in attitudes towards and frequency of using TELL tools in learning English in terms of the year of study. However, students of different levels of academic achievements have different attitudes towards using TELL tools and use TELL tools to learn English differently. Received 2nd May 2019; Revised 16th July 2019, Accepted 20th October 2019

OVARIAN ASCORBIC ACID DEPLETION TEST FOR LUTEINIZING HORMONE

1967 ◽  
Vol 56 (4) ◽  
pp. 619-625 ◽  
Author(s):  
Hans Jacob Koed ◽  
Christian Hamburger
Keyword(s):  
Ascorbic Acid ◽  
Luteinizing Hormone ◽  
Dose Response ◽  
Response Curve ◽  
Dose Response Curve ◽  
Human Origin ◽  
Response Curves ◽  
Significant Difference ◽  
The Mean ◽  
Different Levels

ABSTRACT Comparison of the dose-response curves for LH of ovine origin (NIH-LH-S8) and of human origin (IRP-HMG-2) using the OAAD test showed a small, though statistically significant difference, the dose-response curve for LH of human origin being a little flatter. Two standard curves for ovine LH obtained with 14 months' interval, were parallel but at different levels of ovarian ascorbic acid. When the mean ascorbic acid depletions were calculated as percentages of the control levels, the two curves for NIH-LH-S8 were identical. The use of standards of human origin in the OAAD test for LH activity of human preparations is recommended.

scholarly journals Association of Calcium Supplementation During Pregnancy with the Birth Weight of Single-Born Neonates in Rural Northwest China

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 1106-1106
Author(s):  
Gao Xiangyu ◽  
Mi Baibing ◽  
Dang Shaonong ◽  
Yan Hong
Keyword(s):  
Birth Weight ◽  
Gestational Age ◽  
Regression Models ◽  
Calcium Supplementation ◽  
Northwest China ◽  
Incidence Rates ◽  
Shaanxi Province ◽  
Significant Difference ◽  
Birth Weight Percentile ◽  
Weight Percentile

Abstract Objectives To investigate the association of calcium supplementation during the pregnancy with the birth weight of single-born neonates. Methods The survey employed a multistage, stratified and random sampling to investigate 15–49 aged pregnant women in 2010 to 2013 in Shaanxi province. A self - designed questionnaire was utilized. Birth weight between the 10(th) and 90(th) percentile was classified as appropriate for gestational age(AGA) infants. Chi-square test and logistic regression models were conducted to evaluate the association of calcium supplementation with single-born neonatal birth weight. Results A total of 28,490 women was enrolled in this study, 17 349 (60.9%) of participants had calcium supplementation during pregnancy. The incidence rates of small and large gestational age infants were 13.5% and 8.3%, respectively. The study conducted that calcium supplementation had a statistically significant difference in SGA (birth weight percentile <10) (P < 0.01). After adjusting the regression models by confounding factors, we found that calcium supplementation was still protective towards SGA birth, the difference was statistically significant (OR = 0.89, 95% CI: 0.82–0.96, P < 0.05), but there was no significant difference in the birth to LGA (birth weight percentile <10). Conclusions Calcium supplementation during pregnancy reduced the risk of SGA, but was not associated with the birth of LGA. Funding Sources

scholarly journals FRI0431 PROFILE OF INFECTIOUS SPONDYLODISCITIS ACCORDING TO THE SITE: UNIFOCAL VERSUS MULTIFOCAL

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 814.3-814
Author(s):  
A. Ben Tekaya ◽  
L. Ben Ammar ◽  
M. Ben Hammamia ◽  
O. Saidane ◽  
S. Bouden ◽  
...  
Keyword(s):  
Current Problem ◽  
Common Factor ◽  
Cord Compression ◽  
Posterior Arch ◽  
Significant Difference ◽  
Infectious Spondylodiscitis ◽  
Vertebral Biopsy ◽  
Inflammatory Syndrome ◽  
Different Levels ◽  
A Current

Background:Infectious spondylodiscitis is a therapeutic emergency and is a current problem. It can affect the different levels of the spine. Multifocal forms, touching several floors, however remain rare.Objectives:To compare the clinical, biological, radiological and therapeutic aspects of unifocal versus multifocal spondylodiscitis.Methods:This is a retrospective study of 113 patients admitted to our service over a period of 20 years [1998-2018]. The diagnosis of spondylodiscitis was made on the basis of clinical, biological, radiological and bacteriological data. We have divided our population into two groups: unifocal and multifocal spondylodiscitis.Results:Spondylodiscitis was more frequently unifocal (75.2%) than multifocal (24.8%). The average age of the patients was 55.8 years. There were 62 men and 51 women. There was no difference in age and sex between the two groups (p=0.5 and p=0.8, respectively).Diabetes was more frequent in the group of multifocal spondylodiscitis but with no statistically significant difference (p=0.4). No statistically significant difference between the two groups regarding the start mode (p=0.7), the schedule (p=0.3), the presence of neurological signs (p=0.7), fever (p = 0.2), impaired general condition (p=0.6) and biological inflammatory syndrome (p=0.6).Cervical and dorsal spine involvement was more common in multifocal spondylodiscitis (p = 0.02 and p = 0.01; respectively). There were 11 spondylodiscitis involving 2 floors (cervical and dorsal: 2 cases, cervical and lumbar: 3 cases, dorsal and lumbar: 6 cases) and 3 spondylodiscitis involving 3 floors.Radiologically, the presence of vertebral fracture and involvement of the posterior arch was more frequent during the multifocal form (p=0.03 and p=0.001; respectively). The frequency of para-vertebral abscesses, epiduritis and the presence of spinal cord compression were similar in the two groups (p=0.6; p=0.7 and p=0.2, respectively).Tuberculosis was more frequent during the multifocal form (p = 0.05) and brucellosis during the unifocal form (p = 0.03). Disco-vertebral biopsy was performed in 79 cases. It was more often contributory during multifocal spondylodiscitis (p = 0.03).The occurrence of immediate complications was more frequent in multifocal spondylodiscitis but with no statistically significant difference (p=0.2).Conclusion:Multifocal sppondylodiscitis is seen mainly in immunocompromised subjects. Our study found that diabetes is the most common factor in immunosuppression. Note also the predominance of involvement of the posterior elements, tuberculous origin and immediate complications.Disclosure of Interests:None declared

scholarly journals The morality of abusing a robot

2020 ◽  
Vol 11 (1) ◽  
pp. 271-283
Author(s):  
Christoph Bartneck ◽  
Merel Keijsers
Keyword(s):  
Mediation Analysis ◽  
Aggressive Behaviour ◽  
Video Clips ◽  
Significant Difference ◽  
Abusive Behaviour ◽  
Different Levels ◽  
Identical Behaviour

AbstractIt is not uncommon for humans to exhibit abusive behaviour towards robots. This study compares how abusive behaviour towards a human is perceived differently in comparison with identical behaviour towards a robot. We showed participants 16 video clips of unparalleled quality that depicted different levels of violence and abuse. For each video, we asked participants to rate the moral acceptability of the action, the violence depicted, the intention to harm, and how abusive the action was. The results indicate no significant difference in the perceived morality of the actions shown in the videos across the two victim agents. When the agents started to fight back, their reactive aggressive behaviour was rated differently. Humans fighting back were seen as less immoral compared with robots fighting back. A mediation analysis showed that this was predominately due to participants perceiving the robot’s response as more abusive than the human’s response.

scholarly journals Multi-Year NDVI Values as Indicator of the Relationship between Spatiotemporal Vegetation Dynamics and Environmental Factors in the Qaidam Basin, China

2021 ◽  
Vol 13 (7) ◽  
pp. 1240
Author(s):  
Junpeng Lou ◽  
Guoyin Xu ◽  
Zhongjing Wang ◽  
Zhigang Yang ◽  
Sanchuan Ni
Keyword(s):  
Environmental Factors ◽  
Vegetation Dynamics ◽  
Vegetation Index ◽  
Qaidam Basin ◽  
Elevation Gradient ◽  
Practical Significance ◽  
Elevation Gradients ◽  
Relative Contribution ◽  
Significant Difference ◽  
Different Altitudes

The Qaidam Basin is a unique and complex ecosystem, wherein elevation gradients lead to high spatial heterogeneity in vegetation dynamics and responses to environmental factors. Based on the remote sensing data of Moderate Resolution Imaging Spectroradiometer (MODIS), Tropical Rainfall Measuring Mission (TRMM) and Global Land Data Assimilation System (GLDAS), we analyzed the spatiotemporal variations of vegetation dynamics and responses to precipitation, accumulative temperature (AT) and soil moisture (SM) in the Qaidam Basin from 2001 to 2016. Moreover, the contribution of those factors to vegetation dynamics at different altitudes was analyzed via an artificial neural network (ANN) model. The results indicated that the Normalized Difference Vegetation Index (NDVI) values in the growing season showed an overall upward trend, with an increased rate of 0.001/year. The values of NDVI in low-altitude areas were higher than that in high-altitude areas, and the peak values of NDVI appeared along the elevation gradient at 4400–4600 m. Thanks to the use of ANN, we were able to detect the relative contribution of various environmental factors; the relative contribution rate of AT to the NDVI dynamic was the most significant (35.17%) in the low-elevation region (< 2900 m). In the mid-elevation area (2900–3900 m), precipitation contributed 44.76% of the NDVI dynamics. When the altitude was higher than 3900 m, the relative contribution rates of AT (39.50%) and SM (38.53%) had no significant difference but were significantly higher than that of precipitation (21.97%). The results highlight that the different environmental factors have various contributions to vegetation dynamics at different altitudes, which has important theoretical and practical significance for regulating ecological processes.

Sign in / Sign up

Export Citation Format

Share Document