scholarly journals Experimental and Numerical Investigation of Dustfall Effect on Remote Sensing Retrieval Accuracy of Chlorophyll Content

Sensors ◽  
2019 ◽  
Vol 19 (24) ◽  
pp. 5530
Author(s):  
Baodong Ma ◽  
Xuexin Li ◽  
Aiman Liang ◽  
Yuteng Chen ◽  
Defu Che

Chlorophyll is the dominant pigment in the photosynthetic light-harvesting complexes that is related to the physiological function of leaves and is responsible for light absorption and energy transfer. Dust pollution has become an environmental problem in many areas in China, indicating that accurately estimating chlorophyll content of vegetation using remote sensing for assessing the vegetation growth status in dusty areas is vital. However, dust deposited on the leaf may affect the chlorophyll content retrieval accuracy. Thus, quantitatively studying the dustfall effect is essential. Using selected vegetation indices (VIs), the medium resolution imaging spectrometer terrestrial chlorophyll index (MTCI), and the double difference index (DD), we studied the retrieval accuracy of chlorophyll content at the leaf scale under dusty environments based on a laboratory experiment and spectra simulation. First, the retrieval accuracy under different dustfall amounts was studied based on a laboratory experiment. Then, the relationship between dustfall amount and fractional dustfall cover (FDC) was experimentally analyzed for spectra simulation of dusty leaves. Based on spectral data simulated using a PROSPECT-based mixture model, the sensitivity of VIs to dust under different chlorophyll contents was analyzed comprehensively, and the MTCI was modified to reduce its sensitivity to dust. The results showed that (1) according to experimental investigation, the DD model provides low retrieval accuracy, the MTCI model is highly accurate when the dustfall amount is less than 80 g/m2, and the retrieval accuracy decreases significantly when the dustfall amount is more than 80 g/m2; (2) a logarithmic relationship exists between FDC and dustfall amount, and the PROSPECT-based mixture model can simulate the leaf spectra under different dustfall amounts and different chlorophyll contents with a root mean square error of 0.015; and (3) according to numerical investigation, MTCI’s sensitivity to dust in the chlorophyll content range of 25 to 60 μg/cm2 is lower than in other chlorophyll content ranges; DD’s sensitivity to dust was generally high throughout the whole chlorophyll content range. These findings may contribute to quantitatively understanding the dustfall effect on the retrieval of chlorophyll content and would help to accurately retrieve chlorophyll content in dusty areas using remote sensing.

Author(s):  
Yuteng Chen ◽  
Baodong Ma ◽  
Xuexin Li ◽  
Song Zhang ◽  
Lixin Wu

Dust pollution is serious in many areas of China. It is of great significance to estimate chlorophyll content of vegetation accurately by hyperspectral remote sensing for assessing the vegetation growth status and monitoring the ecological environment in dusty areas. By using selected vegetation indices including Medium Resolution Imaging Spectrometer Terrestrial Chlorophyll Index (MTCI) ,Double Difference Index (DD) and Red Edge Position Index (REP), chlorophyll inversion models were built to study the accuracy of hyperspectral inversion of chlorophyll content based on a laboratory experiment. The results show that: (1) REP exponential model has the most stable accuracy for inversion of chlorophyll content in dusty environment. When dustfall amount is less than 80&amp;thinsp;g/m<sup>2</sup>, the inversion accuracy based on REP is stable with the variation of dustfall amount. When dustfall amount is greater than 80&amp;thinsp;g/m<sup>2</sup>, the inversion accuracy is slightly fluctuation. (2) Inversion accuracy of DD is worst among three models. (3) MTCI logarithm model has high inversion accuracy when dustfall amount is less than 80&amp;thinsp;g/m<sup>2</sup>; When dustfall amount is greater than 80&amp;thinsp;g/m<sup>2</sup>, inversion accuracy decreases regularly and inversion accuracy of modified MTCI (mMTCI) increases significantly. The results provide experimental basis and theoretical reference for hyperspectral remote sensing inversion of chlorophyll content.


2015 ◽  
Vol 8 (1) ◽  
pp. 68
Author(s):  
B. Chutichudet ◽  
Prasit Chutichudet ◽  
Usana Trainoak

<p>‘Maha Chanok’<strong> </strong>mango is an economic fruit crop widely cultivated commercially throughout Thailand. By nature, mango fruit has a rather limited storage life after harvest. 1-methylcyclopropene (1-MCP) has been accepted as a commercial substance to improve several fruit qualities. The objective of this research was to study the effects of 1-MCP on the external postharvest qualities and storage life on the ‘Maha Chanok’ mango fruit. The experiment was laid out in a Completely Randomized Design with three replicates, ten fruits per replicate. Mango fruit was fumigated with 1-MCP at three concentrations (1000, 1250, or 1500 nl l<sup>-1</sup>) and three fumigation periods (12, 18, or 24 h), compared with the control fruit. After treating, all treatments were stored under ambient temperature (27 °C, 80%R.H.). The following determinations were made every two days for assessment of fruit weight loss, firmness, chlorophyll content, decay incidence, and storage life. The results showed that fruit treated with 1500 nl l<sup>-1</sup><strong> </strong>1-MCP for 24 h had the maximal fruit firmness. For chlorophyll content, the results showed that fruit-treated with 1500 nl l<sup>-1</sup><strong> </strong>1-MCP for 12 h could effectively retain the highest chlorophyll contents. Furthermore, both the lowest fruit decay and the longest storage life of 12 days were achieved from the fruit treated with 1000 nl l<sup>-1</sup><strong> </strong>1-MCP for 12 h.</p>


1996 ◽  
Vol 121 (1) ◽  
pp. 69-76 ◽  
Author(s):  
Ursula Schuch ◽  
Richard A. Redak ◽  
James Bethke

Six cultivars of poinsettia (Euphorbia pulcherrima Wind.), `Angelika White', `Celebrate 2', `Freedom Red', `Lilo Red', `Red Sails', and `Supjibi Red' were grown for 9 weeks during vegetative development under three constant-feed fertilizer treatments, 80,160, or 240 mg N/liter and two irrigation regimes, well-watered (high irrigation) or water deficient (low irrigation). Plants fertilized with 80 or 240 mg N/liter were 10% to 18% shorter, while those fertilized with 160 mg N/liter were 25 % shorter with low versus high irrigation. Leaf area and leaf dry weight increased linearly in response to increasing fertilizer concentrations. Low irrigation reduced leaf area, leaf, stem, and shoot dry weight 3670 to 41%. Cultivars responded similarly to irrigation and fertilizer treatments in all components of shoot biomass production and no interactions between the main effects and cultivars occurred. Stomatal conductance and transpiration decreased with increasing fertilizer rates or sometimes with low irrigation. Highest chlorophyll contents occurred in leaves of `Lilo Red' and `Freedom Red'. Leaves of plants fertilized with 80 mg N/liter were deficient in leaf N and had 40 % to 49 % lower leaf chlorophyll content compared to plants fertilized with 160 or 240 mg N/liter. Irrigation had no effect on leaf N or chlorophyll content. At the end of the experiment leaves of `Supjibi Red' and `Angelika White' contained higher concentrations of soluble proteins than the other four cultivars.


2020 ◽  
Vol 31 (2) ◽  
pp. 127-137
Author(s):  
Chatarina Lilis Suryani ◽  
◽  
Tutik Dwi Wahyuningsih ◽  
Supriyadi Supriyadi ◽  
Umar Santoso ◽  
...  

Plant leaves are the primary source of natural colorants for food, mainly due to their chlorophyll content. However, the plant types and the degree of leaf maturity determine the quality and quantity of the chlorophyll. This study aimed to determine the best maturity level of pandan (Pandanus amaryllifolius Roxb.) leaves that serves as potential source of chlorophyll for natural food colorants. Eighty three pandan plants obtained from six different farming locations in Bantul Regency, Yogyakarta, Indonesia were used as samples. The leaves were grouped into four levels of maturity using descriptive statistics based on their morphology, anatomy, color, and chlorophyll contents. The results showed that the average number of leaves ranged from 20-24 leaves per plant (at 95% confidence interval), and 96.4% of the plant had a maximum of 24 leaves. The leaf maturity was grouped into (1) young, (2) medium, (3) mature, and (4) over mature, corresponding to leaf number 1-6, 7-12, 13-18, and 19-24, respectively. The higher the leaf maturity, the higher the chlorophyll content. However, the over mature leaves were only slightly different from the mature ones. In addition, pandan leaves have specific flavor and contain carotenoid, phenolic, and flavonoid substances. Anatomically, the mesophyll’s size was greatest in the mature leaves, while the size of chloroplast was not significantly different from medium to over mature leaves. Based on the chlorophyll content and mesophyll size, it was concluded that mature pandan leaves were the best source of chlorophyll, containing chlorophyll of 623.08 mg/100 g dry weight (DW).


2021 ◽  
Vol 13 (22) ◽  
pp. 4671
Author(s):  
Bing Lu ◽  
Yuhong He

Chlorophyll is an essential vegetation pigment influencing plant photosynthesis rate and growth conditions. Remote sensing images have been widely used for mapping vegetation chlorophyll content in different ecosystems (e.g., farmlands, forests, grasslands, and wetlands) for evaluating vegetation growth status and productivity of these ecosystems. Compared to farmlands and forests that are more homogeneous in terms of species composition, grasslands and wetlands are more heterogeneous with highly mixed species (e.g., various grass, forb, and shrub species). Different species contribute differently to the ecosystem services, thus, monitoring species-specific chlorophyll content is critical for better understanding their growth status, evaluating ecosystem functions, and supporting ecosystem management (e.g., control invasive species). However, previous studies in mapping chlorophyll content in heterogeneous ecosystems have rarely estimated species-specific chlorophyll content, which was partially due to the limited spatial resolution of remote sensing images commonly used in the past few decades for recognizing different species. In addition, many previous studies have used one universal model built with data of all species for mapping chlorophyll of the entire study area, which did not fully consider the impacts of species composition on the accuracy of chlorophyll estimation (i.e., establishing species-specific chlorophyll estimation models may generate higher accuracy). In this study, helicopter-acquired high-spatial resolution hyperspectral images were acquired for species classification and species-specific chlorophyll content estimation. Four estimation models, including a universal linear regression (LR) model (i.e., built with data of all species), species-specific LR models (i.e., built with data of each species, respectively), a universal random forest regression (RFR) model, and species-specific RFR models, were compared to determine their performance in mapping chlorophyll and to evaluate the impacts of species composition. The results show that species-specific models performed better than the universal models, especially for species with fewer samples in the dataset. The best performed species-specific models were then used to generate species-specific chlorophyll content maps using the species classification results. Impacts of species composition on the retrieval of chlorophyll content were further assessed to support future chlorophyll mapping in heterogeneous ecosystems and ecosystem management.


2012 ◽  
Vol 20 (1) ◽  
pp. 97-114 ◽  
Author(s):  
Elżbieta Węgrzynowicz-Lesiak ◽  
Marian Saniewski ◽  
Justyna Góraj ◽  
Marcin Horbowicz ◽  
Kensuke Miyamoto ◽  
...  

ABSTRACT The purpose of this study was to clarify the effect of sucrose on auxin-induced growth of stem excised from growing tulips and excised directly from cooled and not cooled bulbs, and on the growth of excised IV internode from growing plants in the presence of auxin. In all cases flower bud was replaced by IAA (indole-3- acetic acid, 0.1%, w/w in lanolin) and basal part of excised segments of stem was kept in distilled water or in solution of various sugars at different concentrations. IAA-induced growth of excised stems isolated from growing tulips was inhibited by sucrose at concentrations of 5.0% and 10.0%, but sucrose at 1.25% and 2.5% did not. Sucrose at all concentrations used evidently delayed senescence and increased chlorophyll contents in excised stems in the presence of IAA. Sucrose induced stiffing in isolated stems in the presence of IAA, and much less infective by pathogen in comparison to stem treated with IAA only. Mannitol and sorbitol at concentrations of 5.0% and 10.0% substantially inhibited IAA-induced growth of stem segments. Stem segments excised from cooled and not cooled tulip bulbs were more sensitive than those isolated from growing shoots due to application of sucrose and glucose; more inhibitory effect was observed. Sucrose at concentrations of 5.0% and 10.0% only slightly inhibited growth of IV internode treated with IAA and all concentrations of sucrose (1.25%, 2.5%, 5.0% and 10.0%) substantially increased chlorophyll content. The possible mode of actions of sucrose interacting with auxin to regulate stem growth is also discussed although sugar response is complicated by the fact that plants have multiple sugar-response pathways.


2000 ◽  
Vol 76 (6) ◽  
pp. 941-952 ◽  
Author(s):  
Paul H. Sampson ◽  
Gina H. Mohammed ◽  
Thomas L. Noland ◽  
Denzil Irving ◽  
Stephen J. Colombo ◽  
...  

Objective measures of forest ecosystem condition are needed to gauge the effects of management activities and natural phenomena on sustainability. The Bioindicators of Forest Condition Project seeks to develop a Forest Condition Rating (FCR) system using a physiological, remote sensing approach. In particular, the goal of the project is to test whether hyperspectral remote sensing may be used to infer stand-level information about pigment concentration, chlorophyll fluorescence, and other physiological features of condition. The project spans a four-year period of intensive sampling in tolerant hardwood forests in Ontario using the Compact Airborne Spectrographic Imager (CASI). For each airborne campaign, concurrent ground-based sampling for leaf physiological features was performed. Controlled laboratory and greenhouse studies were also conducted to derive relationships between leaf-based spectral measurements and physiology in the presence of environmental stresses. The project has identified several promising bioindicators of strain that are discernible from hyperspectral images and related to ground-based physiology. The most promising remote indicator for semi-operational testing is estimation of chlorophyll content, which can be used to classify maple stands on a five-stage scale of health. Chlorophyll fluorescence has also been discerned from spectral signatures, but our studies indicate it may be confounded by chlorophyll content. The intent here is to update the forestry community on progress made, insights gained, and the practical implications of the research. Keywords: chlorophyll fluorescence, hyperspectral, indices, pigments, reflectance, tolerant hardwoods


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