scholarly journals Assessing shaded-leaf effects on photochemical reflectance index (PRI) for water stress detection in winter wheat

2019 ◽  
Vol 16 (15) ◽  
pp. 2937-2947 ◽  
Author(s):  
Xin Yang ◽  
Shishi Liu ◽  
Yinuo Liu ◽  
Xifeng Ren ◽  
Hang Su
Keyword(s):  
Water Stress ◽  
Winter Wheat ◽  
Water Status ◽  
Control Treatment ◽  
Growth Stages ◽  
Linear Regression Models ◽  
Photochemical Reflectance Index ◽  
Crop Density ◽  
The Difference ◽  
The Impact

Abstract. The photochemical reflectance index (PRI) has emerged to be a pre-visual indicator of water stress. However, whether the varying shaded-leaf fractions, which may be caused by multiple view angles or the changing crop density in the field, affect the performance of PRI in detecting water stress of crops is still uncertain. This study evaluated the impact of the varying shaded-leaf fractions on estimating relative water content (RWC) across growth stages of winter wheat using seven formulations of PRI. Results demonstrated that for the control treatment the mean PRI of sunlit leaves was slightly higher than those of shaded leaves, but the difference between PRI of sunlit and shaded leaves increased as water resources became more limiting. Despite the difference between PRI of sunlit and shaded leaves, the significance of the linear relationship between RWC and most studied formulations of PRI did not show obvious variations with shadow fractions, except for the 100 % shaded-leaf condition. Among the studied formulations of PRI, PRI3 based on reflectance at 512 nm as the reference band provided the most accurate estimates of RWC with varying shaded-leaf fractions, except for the 100 % shaded-leaf condition. The slope and the intercept of linear regression models with PRI3 also showed minimized variations with shaded-leaf fractions. We then applied a uniform RWC prediction model to the data of varying shaded-leaf fractions and found that the accuracy of RWC predictions was not significantly affected in the mixture of sunlit and shaded leaves. However, RWC estimated with PRI of the 100 % shaded-leaf condition had the highest root mean square error (RMSE), implying that PRI of the pure shaded leaves may yield inaccurate estimates of plant water status.

scholarly journals Assessing shadow effects on Photochemical Reflectance Index (PRI) for the water stress detection in winter wheat

2018 ◽  
Author(s):  
Xin Yang ◽  
Shishi Liu ◽  
Yinuo Liu ◽  
Xifeng Ren ◽  
Hang Su
Keyword(s):  
Water Stress ◽  
Linear Regression ◽  
Winter Wheat ◽  
Growth Stages ◽  
Stress Detection ◽  
Photochemical Reflectance Index ◽  
Crop Density ◽  
Relative Water ◽  
The Difference ◽  
The Impact

Abstract. The photochemical reflectance index (PRI) has emerged to be a pre-visual indicator of water stress. However, whether the varying shadow fraction, which may be caused by multiple view angles or the changing crop density in the field, affects the performance of PRI in detecting water stress of crops is still uncertain. This study evaluated the impact of the varying shadow fraction on estimating relative water content (RWC) across growth stages of winter wheat using different formulations of PRI. Results demonstrated that PRI570, PRI1, and PRI2 of shadow were higher than those of sunlit leaves for unstressed plants, but the contrary results were achieved for stressed plants. Despite the difference between PRI_shadow and PRI_leaf, the significance of the linear relationship between RWC and PRI did not change with the different ratio of sunlit leaves and shadow. For most studied PRI formulations, the slope and intercept of the linear regression model between PRI and RWC changed proportionally with the shadow fractions. We applied a uniform RWC prediction model to the data of varying shadow fractions and found that the accuracy of RWC predictions was not significantly affected, indicating that the effect of varying shadow fractions was minimal to the seasonal water stress detection in winter wheat using PRI.

scholarly journals Profile of the Change in Depression during Proton-Pump Inhibitor Therapy in Patients with Gastroesophageal Reflux Disease: Influence of the Mucosal Break

2021 ◽  
Vol 18 (11) ◽  
pp. 5964
Author(s):  
Chia-Liang Wu ◽  
Chien-Lin Chen ◽  
Shu-Hui Wen
Keyword(s):  
Gastroesophageal Reflux Disease ◽  
Gastroesophageal Reflux ◽  
Proton Pump ◽  
Reflux Disease ◽  
Proton Pump Inhibitor Therapy ◽  
Linear Regression Models ◽  
Independent Variable ◽  
The Difference ◽  
Mucosal Break ◽  
The Impact

Given the frequent concomitance between depression and gastroesophageal reflux disease (GERD), it is important to evaluate the change of depression in patients with GERD, especially considering the presence of esophageal mucosal breaks (MB). This study aimed to examine the change in the levels of depression in patients with GERD during proton-pump inhibitors (PPI) therapy. We designed a prospective cohort study to explore the profile of the alteration in depression with respect to the impact of esophageal MB. This study recruited 172 eligible patients with GERD between February 2016 and May 2018. The change in depression was defined as the difference between the respective Taiwanese Depression Questionnaire (TDQ) scores obtained at baseline and after PPI therapy. Multivariate linear regression models were used to estimate the factors associated with the change in depression. The results revealed statistically significant improvements in the TDQ score (mean score: baseline = 13.2, after PPI therapy = 10.9, p < 0.01, Cohen’s d = 0.30) during PPI therapy for GERD. Moreover, the MB was an independent variable associated with changes in the TDQ score [B = 3.31, 95% confidence interval (CI): (1.12, 5.51), p < 0.01] and the improvement in depression [odds ratio = 0.38, 95% CI: (0.17, 0.86), p = 0.02]. Our findings revealed that depressive symptoms improved slightly following PPI therapy. Moreover, MB was an unfavorable prognostic factor for the improvement in depression.

scholarly journals The Modification of Difference Vegetation Index (DVI) in middle and late growing period of winter wheat and its application in soil moisture inversion

2019 ◽  
Vol 131 ◽  
pp. 01098
Author(s):  
Zhang Hong-wei ◽  
Huai-liang Chen ◽  
Fei-na Zha
Keyword(s):  
Soil Moisture ◽  
Winter Wheat ◽  
Vegetation Index ◽  
Vegetation Coverage ◽  
Growth Stages ◽  
Wheat Growth ◽  
Inversion Result ◽  
Growing Period ◽  
The Difference ◽  
Different Growth Stages

In the middle and late growing period of winter wheat, soil moisture is easily affected by saturation when using MODIS data to retrieve soil moisture. In this paper, in order to reduce the effect of the saturation caused by increasing vegetation coverage in middle and late stage of winter wheat, the Difference Vegetation Index (DVI) model was modified with different coefficients in different growth stages of winter wheat based on MODIS spectral data and LAI characteristics of variation. LAI was divided into three stages, LAI ≤ 1 < LAI ≤, 3 < LAI, and the adjusting coefficient of α=1, α=3, α=5, were taken to modifying the Difference Vegetation Index(DVI). The results show that the Modified Difference Vegetation Index (MDVIα) can effectively reduce the interference of saturation, and the inversion result of soil moisture in the middle and late period of winter wheat growth is obviously superior to the uncorrected inversion model of DVI.

On the use of different approaches based on photochemical reflectance index and surface temperature to monitor the water status of winter wheat in semi-arid regions

2020 ◽  
Author(s):  
Zoubair Rafi ◽  
Valérie Le Dantec ◽  
Olivier Merlin ◽  
Said Khabba ◽  
Patrick Mordelet ◽  
...  
Keyword(s):  
Water Stress ◽  
Winter Wheat ◽  
Surface Temperature ◽  
Water Status ◽  
Stress Index ◽  
Coefficient Of Determination ◽  
Temperature Index ◽  
Water Stress Index ◽  
Semi Arid

&lt;p&gt;Agriculture is considered to be the human activity that consumes the most mobilized water on a global scale. However, crops planted in semi-arid areas regularly face periods of moderate to extreme water stress. Such water stress periods have a considerable impact on the seasonal yield of these crops. In order to participate in a more rational irrigation water management, monitoring of the rapid changes in plant water status is necessary. For this purpose, the combination of two different wavelength ranges will be explored : an index based on Xanthophyll cycle (Photochemical Reflectance Index, PRI) and a commonly-used index from thermal infrared spectral range (LST). An experiment on winter wheat was carried out over two agricultural campaigns (2016 to 2018) in the Haouz basin, which is located in the Marrakech region, to better assimilate the temporal dynamics of PRI and surface temperature. In this study, four different approaches are proposed to study the functioning of wheat : 1- an approach based on solar angle to remove the structure effect (PRI&lt;sub&gt;0&lt;/sub&gt;) from the PRI signal and to derive a water stress index PRI&lt;sub&gt;j&lt;/sub&gt;, 2- an approach based on global radiation (R&lt;sub&gt;g&lt;/sub&gt;) to extrapolate a theoretical PRI (PRI&lt;sub&gt;th&lt;/sub&gt;) for R&lt;sub&gt;g&lt;/sub&gt; equal to zero and to calculate a water stress index PRI&lt;sub&gt;lin&lt;/sub&gt;, 3- an approach that determines an optimal PRI (PRI&lt;sub&gt;pot&lt;/sub&gt;) on the basis of the available water content (AWC) criterion in order to derive a stress index I-PRI and 4- an energy balance approach to extract dry and wet surface temperatures in order to establish a normalized surface temperature index (T&lt;sub&gt;norm&lt;/sub&gt;). The results of this work show a strong correlation between the PRI&lt;sub&gt;0&lt;/sub&gt; and the Leaf Area Index with a coefficient of determination equal to 0.92, indicating that it is possible to isolate the structural effects of wheat on the PRI signal. In addition, over the range of variation in AWC, a significant correlation with PRI&lt;sub&gt;j&lt;/sub&gt;, PRI&lt;sub&gt;jlin&lt;/sub&gt; and I-PRI was observed with coefficients of determination of 0.71, 0.42 and 0.24, respectively. In contrast to the T&lt;sub&gt;norm&lt;/sub&gt;, which varies only for values of AWC below 30%, a coefficient of determination of 0.22 is obtained. Finally, the PRI allows us to acquire early and complete information on the response of wheat to change in AWC as opposed to the surface temperature index, revealing the potential of the PRI to monitor the water status of plants and their responses to changing environmental conditions.&lt;/p&gt;

scholarly journals Categorization of the water status of rice inoculated with arbuscular mycorrhizae and with water deficit

2021 ◽  
pp. 339-355
Author(s):  
Michel Ruiz Sánchez ◽  
Juan Adriano Cabrera Rodríguez ◽  
José M. Del'Anico Rodríguez ◽  
Yaumara Muñoz Hernández ◽  
Ricardo Aroca Álvarez ◽  
...  
Keyword(s):  
Water Stress ◽  
Water Deficit ◽  
Mycorrhizal Fungi ◽  
Water Status ◽  
Light Stress ◽  
Arbuscular Mycorrhizal ◽  
Arbuscular Mycorrhizal Symbiosis ◽  
Control Treatment ◽  
Mycorrhizal Symbiosis ◽  
Rice Plants

Introduction. The water deficit negatively affects rice plants and limits their productivity. Arbuscular mycorrhizal symbiosis has been shown to improve rice productivity in drought conditions. Objective. To propose a new categorization for the state of water stress of rice plants inoculated (AM) or not with arbuscular mycorrhizal fungi (nonAM) and exposed to water deficit (D) during the vegetative phase. Materials and methods. The experiment was carried out under controlled greenhouse conditions during the years 2009 and 2010 at the Zaidín Experimental Station, Granada, Spain. The rice transplantation was carried out fourteen days after germination to pots with a 5 cm water sheet and at 30, 40, or 50 days after transplantation (DAT) they were subjected to water deficit during a period of 15 days, at which time the water sheet was restored. The control treatment was maintained throughout the cycle under flood conditions (ww). Evaluations were performed at 45, 55, 65 DAT and after recovery at 122 DAT. The harvest was carried out at 147 DAT. Results. The reduction in water supply demonstrated water stress in the plants, manifested by the decrease in the water potential of the leaves. Arbuscular mycorrhizal symbiosis always favored the water status of the plant. Four categories of water status of plants were proposed taking into account water potentials and agricultural yield: no stress (≥-0.67 MPa); light stress (<-0.67 to -1.20 MPa); moderate stress (<-1.20 to -1.60 MPa), and severe stress (<-1.60 MPa). Conclusion. The categorization of stress due to the water deficit is a tool of high scientific value for the specific case of rice, since this plant has the capacity to adapt to tolerate the presence of a sheet of water throughout its biological cycle and is highly susceptible to water deficit.

scholarly journals ↵​Impact of A Selected Mycorrhizal Complex and A Rhizobacterial Species on Tomato Plants’ Growth under Water Stress Conditions

2021 ◽  
Author(s):  
Slimani Afafe ◽  
Harkousse Oumaima ◽  
Mazri Mouaad Amine ◽  
Zouahri Abdelmajid ◽  
Ouahmane Lahcen ◽  
...  
Keyword(s):  
Water Stress ◽  
Mycorrhizal Fungi ◽  
Growth Parameters ◽  
Water Status ◽  
Field Capacity ◽  
Water Levels ◽  
Stress Conditions ◽  
Bacillus Sp ◽  
Tomato Plants ◽  
The Impact

Background: Plant strategies for adapting to drought could be improved by associations between plant roots and soil microorganisms, including arbuscular mycorrhizal fungi (AMF) and plant growth promoting rhizobacteria (PGPR). In this study, the impact of a selected AMF complex and a selected PGPR species on the growth of tomato (Lycopersicum esculentum Mill.) under induced water stress was evaluated. Methods: Three different inoculation treatments were applied to tomato seedlings (a complex of AMF composed mainly of Glomus genus a Bacillus sp. PGPR treatment and a combination of both) and three different water levels (75%, 50% and 25% of field capacity). Result: A significant damaging impact of drought on tomato growth parameters and root mycorrhizal colonization, although the presence of microbes stimulated tomato plants growth and decreased the impact ofdrought stress. Indeed inoculated plants presented greater heights, fresh and dry weights, leaves number and area; greater water status; and greater proteins, sugars and chlorophylls contents either with the AMF complex or the Bacillus sp. in normal and drought stress conditions compared to the non-inoculated plants. However dual inoculation recorded the highest values under all water levels treatments.

The impact of pain on the course of ADL functioning in patients with dementia

2020 ◽  
Author(s):  
Annelore H van Dalen-Kok ◽  
Marjoleine J C Pieper ◽  
Margot W M de Waal ◽  
Jenny T van der Steen ◽  
Erik J A Scherder ◽  
...  
Keyword(s):  
Pain Management ◽  
Pain Score ◽  
Nursing Home Residents ◽  
Linear Regression Models ◽  
Dutch Version ◽  
The Difference ◽  
Item Scores ◽  
The Impact ◽  
The Relationship

Abstract Background Understanding if and how pain influences activities of daily living (ADL) in dementia is essential to improving pain management and ADL functioning. This study examined the relationship between the course of pain and change in ADL functioning, both generally and regarding specific ADL functions. Methods Participants were Dutch nursing home residents (n = 229) with advanced dementia. ADL functioning was assessed with the Katz ADL scale, and pain with the Dutch version of the Pain Assessment Checklist for Seniors with Limited Ability to Communicate (PACSLAC-D). Changes of PACSLAC-D and Katz ADL scores were computed based on the difference in scores between baseline, 3-month and 6-month follow-up. Multivariate linear regression models were used to assess the relationships between change in pain score, change in total ADL score and specific ADL item scores during follow-up. Results At baseline, residents had a median ADL score of 18 (interquartile range 13–22, range 6–24) and 48% of the residents were in pain (PACSLAC-D ≥ 4). Residents with pain were more ADL dependent than residents without pain. A change in pain score within the first 3 months was a significant predictor for a decline in ADL functioning over the 6-month follow-up (B = 0.10, SE = 0.05, P = 0.045), and specifically, a decline on the items ‘transferring’ over the 6-month follow-up and ‘feeding’ during the first 3 months of follow-up. Conclusions Pain is associated with ADL functioning cross-sectionally, and a change in pain score predicts a decline in ADL functioning, independent of dementia severity. Awareness of (changes in) ADL activities is clearly important and might result in both improved recognition of pain and improved pain management.

scholarly journals Response of Cotton Varieties to the Stage of Topping under Rainfed Condition of Bardiya, Nepal

2006 ◽  
Vol 27 ◽  
pp. 165-168 ◽  
Author(s):  
KB Basnet
Keyword(s):  
Block Design ◽  
Growth Stages ◽  
Cotton Yield ◽  
Seed Cotton ◽  
Rainfed Condition ◽  
Seed Cotton Yield ◽  
Significant Difference ◽  
The Difference ◽  
The Impact ◽  
Different Growth Stages

A field experiment was conducted to study the impact of topping at different growth stages (3-4, 6-7, 9-10 and 12-13 sympodial branches) on productivity of two (Tamcot SP-37 and H-777) cotton varieties under rainfed condition at the Kumbher Farm (Bardiya district) of Cotton Development Board in 1995. The experiment was laid out in a Randomized Complete Block Design with four replications. The interaction effect between variety and stages of topping showed that significantly higher yield (1.23 t/ha) was produced by topping plants at the stage of 12-13 sympodial banches of the variety Tamcot SP-37 as compared to all other treatments. At all stages of topping the yield produced by Tamcot SP-37 was significantly higher than H-777. The average seed cotton yield (1.03 t/ha) of Tamcot SP-37 was significantly higher than that of H- 777 (0.71 t/ha) and the difference in yield was 45.0%. The seed-cotton yield increased from 0.75 to 1.00 t/ ha with the postponed of topping from 3-4 to 12-13 sympodial branches, but significant difference was recorded between late (12-13 sympodial branches) and early (3-4 and 6-7 sympodial branches) stages of topping. Thus, for rainfed condition of Bardiya Tamcot SP-37 was a suitable variety with 12-13 sympodial branches as an appropriate stage of topping for sustainable production of cotton. Key words: Variety, topping, sympodial branches. J. Inst. Agric. Anim. Sci. 27:165-168 (2006)

scholarly journals A Rapid Model (COV_PSDI) for Winter Wheat Mapping in Fallow Rotation Area Using MODIS NDVI Time-Series Satellite Observations: The Case of the Heilonggang Region

2021 ◽  
Vol 13 (23) ◽  
pp. 4870
Author(s):  
Xiaoyuan Zhang ◽  
Kai Liu ◽  
Shudong Wang ◽  
Xin Long ◽  
Xueke Li
Keyword(s):  
Time Series ◽  
Winter Wheat ◽  
The Other ◽  
Percentage Error ◽  
Growth Stages ◽  
Traditional Methods ◽  
Rapid Mapping ◽  
Art Methods ◽  
Ndvi Time Series ◽  
The Impact

Rapid and accurate monitoring of spatial distribution patterns of winter wheat over a long period is of great significance for crop yield prediction and farmland water consumption estimation. However, weather conditions and relatively long revisit cycles often result in an insufficient number of continuous medium-high resolution images over large areas for many years. In addition, the cropland pattern changes frequently in the fallow rotation area. A novel rapid mapping model for winter wheat based on the normalized difference vegetation index (NDVI) time-series coefficient of variation (NDVI_COVfp) and peak-slope difference index (PSDI) is proposed in this study. NDVI_COVfp uses the time-series index volatility to distinguish cultivated land from background land-cover types. PSDI combines the key growth stages of winter wheat phenology and special bimodal characteristics, substantially reducing the impact of abandoned land and other crops. Taking the Heilonggang as an example, this study carried out a rapid mapping of winter wheat for four consecutive years (2014–2017), and compared the proposed COV_PSDI with two state-of-the-art methods and traditional methods (the Spectral Angle Mapping (SAM) and the Iterative Self-Organizing Data Analysis Technique Algorithm (ISODATA)). The verification results revealed that the COV_PSDI model improved the overall accuracy (94.10%) by 4% compared with the two state-of-art methods (90.80%, 89.00%) and two traditional methods (90.70%, 87.70%). User accuracy was the highest, which was 93.74%. Compared with the other four methods, the percentage error (PE) of COV_PSDI for four years was the lowest in the same year, with the minimum variation range of PE being 1.6–3.6%. The other methods resulted in serious overestimation. This demonstrated the effectiveness and stability of the method proposed in the rapid and accurate extraction of winter wheat in a large area of fallow crop rotation region. Our study provides insight for remote sensing monitoring of spatiotemporal patterns of winter wheat and evaluation of “fallow rotation” policy implementation.

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