Study On Spectral Characters-Chlorophyll Inversion Model of Sabina Vulgaris in Mu Us Sandy Land

Sabina vulgaris is a group tree species in Mu Us Sandy Land. Understanding the growth status of Sabina vulgaris has guiding value for vegetation change monitoring. Chlorophyll is an important indicator to characterize the growth status of plants, and its content changes are important for analyzing the physiological growth status of plants and guiding the precise planting of plants. In this paper, the spectral reflectance and chlorophyll content of Sabina vulgaris were measured by SVC HR-1024 portable ground feature spectrometer and SPAD502 chlorophyll instrument, and the relationship between ground feature spectral characteristics and chlorophyll content of Sabina vulgaris was studied. The results show that there is a correlation between the vegetation index and chlorophyll, the effect of NDVI is the best, the bands with the highest correlation are the combined bands of 470nm-500nm, 610nm-680nm, and 740nm-840nm, and the wavelengths with the highest correlation are (660,790); Vegetation index, red-edge parameters, and chlorophyll have a certain correlation. The fitting effect of the model established by vegetation index is better than that established by red-edge parameters, and the highest R2 is 0.97; Among the three modeling methods, the model fitting effect of partial least squares is the best, R2 is > 0.91, and the disadvantage is that the processing process is complex; The processing method of the univariate linear regression model is the simplest, but the disadvantage is that the accuracy of the model is unstable, R2 is between 0.1-0.9, so the multivariate linear regression model is the most suitable of the three methods(R2>0.8).

Vanadium Toxicity Induced Changes in Growth, Antioxidant Profiling, and Vanadium Uptake in Pepper (Capsicum annum L.) Seedlings

Heavy metal contamination is one of the current serious environmental and agricultural soil issues, and it is mainly due to anthropogenic activities. Vanadium (V) is found in low concentrations in a wide range of plants and is widely distributed in soils. The current study aimed to determine how pepper seedlings responded to various V concentrations, as well as the detrimental effects of V on growth, root morphological traits, photosynthetic performance, reactive oxygen species (ROS), osmolytes production, antioxidant enzyme activities, and V uptake. Pepper seedlings (5 weeks old) were grown in hydroponic culture with six V levels (0, 10, 20, 30, 40, and 50 mg L−1 NH4VO3). After two weeks of V treatment, low level of V (10, 20 mg L−1) enhanced the growth status, conversely higher V (30, 40, and 50 mg L−1) level reduced the growth. The leaf gas exchange elements, pigments molecules, and root growth characteristics are also affected by higher V concentrations. Moreover, V uptake was higher in roots than in the shoot of pepper seedlings. Similarly, osmolytes content, ROS production, and antioxidant enzymes activities were significantly improved under V stress. Concluding, lower V (10, 20 mg L−1) concentration positively affected pepper growth, and higher V (30, 40, and 50 mg L−1) concentration had a detrimental effect on pepper physiological and biochemical mechanisms.

B- and N-doped carbon dots by one-step microwave hydrothermal synthesis: tracking yeast status and imaging mechanism

Background Carbon dots (CDs) are widely used in cell imaging due to their excellent optical properties, biocompatibility and low toxicity. At present, most of the research on CDs focuses on biomedical application, while there are few studies on the application of microbial imaging. Results In this study, B- and N-doped carbon dots (BN-CDs) were prepared from citric acid, ethylenediamine, and boric acid by microwave hydrothermal method. Based on BN-CDs labeling yeast, the dead or living of yeast cell could be quickly identified, and their growth status could also be clearly observed. In order to further observe the morphology of yeast cell under different lethal methods, six methods were used to kill the cells and then used BN-CDs to label the cells for imaging. More remarkably, imaging of yeast cell with ultrasound and antibiotics was significantly different from other imaging due to the overflow of cell contents. In addition, the endocytosis mechanism of BN-CDs was investigated. The cellular uptake of BN-CDs is dose, time and partially energy-dependent along with the involvement of passive diffusion. The main mechanism of endocytosis is caveolae-mediated. Conclusion BN-CDs can be used for long-term stable imaging of yeast, and the study provides basic research for applying CDs to microbiol imaging. Graphical Abstract

Understanding urban inequalities in children’s linear growth outcomes: a trend and decomposition analysis of 39,049 children in Bangladesh (2000-2018)

Background Despite significant progress in reducing child undernutrition, Bangladesh remains among the top six countries globally with the largest burden of child stunting and has disproportionately high stunting prevalence among the urban poor. We use population representative data to identify key predictors of child stunting in Bangladesh and assess their contributions to linear growth differences observed between urban poor and non-poor children. Methods We combined six rounds of Demographic and Health Survey data spanning 2000-2018 and used official poverty rates to classify the urban population into poor and non-poor households. We identified key stunting determinants using stepwise selection method. Regression-decomposition was used to quantify contributions of these key determinants to poverty-based intra-urban differences in child linear growth status. Results Key stunting determinants identified in our study predicted 84% of the linear growth difference between urban poor and non-poor children. Child’s place of birth (27%), household wealth (22%), maternal education (18%), and maternal body mass index (11%) were the largest contributors to the intra-urban child linear growth gap. Difference in average height-for-age z score between urban poor and non-poor children declined by 0.31 standard deviations between 2000 and 2018. About one quarter of this observed decrease was explained by reduced differentials between urban poor and non-poor in levels of maternal education and maternal underweight status. Conclusions Although the intra-urban disparity in child linear growth status declined over the 2000-2018 period, socioeconomic gaps remain significant. Increased nutrition-sensitive programs and investments targeting the urban poor to improve girls’ education, household food security, and maternal and child health services could aid in further narrowing the remaining linear growth gap.

Assessing the Impacts of Species Composition on the Accuracy of Mapping Chlorophyll Content in Heterogeneous Ecosystems

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.