Estimating nitrogen status of rice using the image segmentation of G-R thresholding method

Wang, Yuan; Wang, Dejian; Zhang, Gang; Wang, Jun

doi:10.1016/j.fcr.2013.04.007

Cited by 135 publications

(109 citation statements)

References 24 publications

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“…A somewhat different approach for calculating the ioninterface surface potential has been recently proposed by Wang and Wang 74 . For the air-water or oil-water interfaces, the two models lead to very similar interaction potentials.…”

Section: Theory: Water-air Interfacementioning

confidence: 99%

Ions at hydrophobic interfaces

Levin

Santos

2014

J. Phys.: Condens. Matter

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We review the present understanding of the behavior of ions at the air-water and oil-water interfaces. We argue that while the alkali metal cations remain strongly hydrated and are repelled from the hydrophobic surfaces, the anions must be classified into kosmotropes and chaotropes. The kosmotropes remain strongly hydrated in the vicinity of a hydrophobic surface, while the chaotropes loose their hydration shell and can become adsorbed to the interface. The mechanism of adsorption is still a subject of debate. Here, we argue that there are two driving forces for anionic adsorption: the hydrophobic cavitational energy and the interfacial electrostatic surface potential of water. While the cavitational contribution to ionic adsorption is now well accepted, the role of the electrostatic surface potential is much less clear. The difficulty is that even the sign of this potential is a subject of debate, with the ab initio and the classical force fields simulations predicting electrostatic surface potentials of opposite sign. In this paper, we will argue that the strong anionic adsorption found in the polarizable force field simulations is the result of the artificial electrostatic surface potential present in the classical water models. We will show that if the adsorption of anions would be as large as predicted by the polarizable force field simulations, the excess surface tension of NaI solution would be strongly negative, contrary to the experimental measurements. While the large polarizability of heavy halides is a fundamental property and must be included in realistic modeling of the electrolytes solutions, we argue that the point charge water models, studied so far, are incompatible with the polarizable ionic force fields when the translational symmetry is broken. The goal for the future should be the development of water models with very low electrostatic surface potential. We believe that such water models will be compatible with the polarizable force fields and can then be used to study the interaction of ions with hydrophobic surfaces and proteins.

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Section: Theory: Water-air Interfacementioning

confidence: 99%

Ions at hydrophobic interfaces

Levin

Santos

2014

J. Phys.: Condens. Matter

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“…However, the high cost and complex operation of the equipment limit the popularization and application of this technology in the field [10,11]. Alternatively, digital images acquired by digital cameras or scanners contain abundant information about colour, morphology, and texture features [11][12][13], which are easy to obtain with existing software. Moreover, the effectiveness of digital images in nutrition diagnosis has been proved in numerous studies [11,[13][14][15].…”

Section: Introductionmentioning

confidence: 99%

“…Alternatively, digital images acquired by digital cameras or scanners contain abundant information about colour, morphology, and texture features [11][12][13], which are easy to obtain with existing software. Moreover, the effectiveness of digital images in nutrition diagnosis has been proved in numerous studies [11,[13][14][15]. Compared to hyperspectral imaging technology, digital image processing technology has the advantages of low cost, simple operation, and good portability in practical applications.…”

Section: Introductionmentioning

confidence: 99%

Utilization of Machine Vision to Monitor the Dynamic Responses of Rice Leaf Morphology and Colour to Nitrogen, Phosphorus, and Potassium Deficiencies

Sun

Gao

Wang

et al. 2018

Journal of Spectroscopy

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Machine vision technology enables the continuous and nondestructive monitoring of leaf responses to different nutrient supplies and thereby contributes to the improvement of diagnostic effects. In this study, we analysed the temporal dynamics of rice leaf morphology and colour under different nitrogen (N), phosphorus (P), and potassium (K) treatments by continuous imaging and further evaluated the effectiveness of dynamic characteristics for identification. e top four leaves (the 1st incomplete leaf and the top three fully expanded leaves) were scanned every three days, and all images were processed in MATLAB to extract the morphological and colour characteristics for dynamic analysis. Subsequently, the mean impact value was applied to evaluate the effectiveness of dynamic indices for identification. According to the results, higher nutrient supply resulted in a faster leaf extension rate and a lower developing rate of chlorosis, and the influence of N deficiency on leaf growth was the greatest, followed by P deficiency and then K deficiency. Furthermore, the optimal indices for identification were mainly calculated from morphological characteristics of the 1st incomplete leaf and colour characteristics of the 3rd fully expanded leaf. Overall, dynamic analysis contributes not only to the exploration of the plant growth mechanism but also to the improvement of diagnostics.

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“…Recently, Rorie et al [10] use an internal calibration disk with a known surface reflectance as a reference for correcting the differences found in a camera's light sensitivity and crop's lighting conditions. Li et al [11] and Wang et al [12] used canopy cover (CC), calculated by digital images using an image analysis program, was highly correlated with growth and N nutrition parameters such as leaf area index LAI, shoot dry weight, and shoot N accumulation. Lee et al [13] also found that digital camera could be employed for characterizing the growth and N nutrition status of rice.…”

Section: Introductionmentioning

confidence: 99%

Determination of Canopys Average SPAD Readings Based on the Analysis of Digital Images

Li¹

2014

Agrotechnol

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Chlorophyll meter SPAD (Soil Plant Analysis Development) is one of the most popular tools used to monitor the N Status of rice (Oryza Sativa L.) but its high price limits it from being widely adopted. Digital imaging analysis used to detect nitrogen offers a promising, inexpensive substitute at canopy level. And the present study evaluated rice canopy SPAD readings by analyzing digital images captured with a domestic digital camera. A field experiment was conducted in 2011 using a completely randomized split-plot design, with main-plot treatments of six N fertilizer application rates and subplot treatments of different plant densities. To remove the image backgrounds, the images were segmented and a dark green color index (DGCI). The index, which is derived from values of hue, saturation, and brightness (HSB), was used to assess the greenness of the rice canopy. The DGCI was significantly correlated with average SPAD readings rice canopy at each growth stage, but the regression lines were different from each other. This might be caused by different lighting conditions, which lead us to conclude a calibration is indispensable when using a digital camera for the diagnosis of a plant's nitrogen status.

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Estimating nitrogen status of rice using the image segmentation of G-R thresholding method

Cited by 135 publications

References 24 publications

Ions at hydrophobic interfaces

Ions at hydrophobic interfaces

Utilization of Machine Vision to Monitor the Dynamic Responses of Rice Leaf Morphology and Colour to Nitrogen, Phosphorus, and Potassium Deficiencies

Determination of Canopys Average SPAD Readings Based on the Analysis of Digital Images

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