Search Results (8)

Accurate prediction of sweet potato yield is crucial for effective crop management. This study investigates the use of vegetation indices (VIs) extracted from multispectral images acquired by a small unmanned aerial vehicle (UAV) throughout the growing season, along with in situ-measured plant physiological parameters, to predict sweet potato yield. The data acquisition process through UAV field imaging is discussed in detail along with the extraction process for the multispectral bands that we use as features. The experiment is designed with a combination of different nitrogen application rates and cover crop treatments. The dependence of VIs and crop physiological parameters, such as leaf chlorophyll content, plant biomass, vine length, and leaf nitrogen content, on yield is evaluated through feature selection methods and model performance. Classical machine learning (ML) approaches and tree-based algorithms, like XGBoost and Random Forest, are implemented. Additionally, a soft-voting ML model ensemble approach is employed to improve performance of yield prediction. Individual models are trained and tested for different cover crop and nitrogen treatments to capture the relationships between the treatments and the target yield variable. The performance of the ML algorithms is evaluated using various popular model performance metrics like R², RMSE, and MAE. Through modelling the data for cover crops and nitrogen treatment rates using individual models, the relationships and effects of different treatments on yield are explored. Important VIs useful for the study are identified through feature selection and model performance evaluation. Full article

Watermelons are in high demand for their juicy texture and sweetness, which is linked to their soluble solids content (SSC). Traditionally, watermelons have been sold as whole fruits. However, the decline in the mean size of households and the very large size of the fruits, together with high prices, mainly at the beginning of the season, mean that supermarkets now sell them as half fruits. For consumers, it is important to know in advance that the fruits that they are purchasing are of a high quality, based not only on external flesh colour but also on sweetness. Near-infrared spectroscopy (NIRS) and Raman spectroscopy were used for the in situ determination of SSC in half watermelons while simulating supermarket conditions. A handheld linear variable filter (LVF) device and an all-in-one (AIO) Process Raman analyser were used for the NIRS and Raman analysis, respectively. The excellent results obtained—including residual predictive deviation for prediction (RPD_p) values of 3.06 and 2.90 for NIRS and Raman, respectively—showed the viability of NIRS and Raman spectroscopies for the prediction of sweetness in half watermelons. Full article

Besides all sharing an extraordinary high (i.e., up to ~450 times) sweetening power as compared to sucrose and while presenting strong similarities in their molecular structures, molecules belonging to the family of diterpene glycosides (i.e., the secondary metabolites of Stevia rebaudiana) differ in specific structural details that strongly impact on their levels of sweetness and bitter aftertaste. Given the nutritional and pharmacological benefits of steviol secondary metabolites as natural dietetic and anti-diabetic remedies, extraction and purification of steviol glycosides from plant material are nowadays widely spread among many countries. However, an unpleasant bitter aftertaste, which is linked to a genetic variation in human bitter taste receptors, hampers the full exploitation of such benefits and calls for a prompt improvement in organoleptic property control of stevia products. A deeper understanding of the molecular structure of different steviol glycosides and the consequent development of promptly measurable criteria for the organoleptic performance of their mixtures will support processing optimization and control of taste profiles within desired yields. The present research aimed at establishing Raman spectroscopic algorithms for quantitative characterizations of raw stevia-based sweetener products. First, a series of twelve high-purity diterpene glycosides were analyzed by high spectrally resolved Raman spectroscopy and their spectra analyzed in order to establish a complete Raman library of molecular structures. Then, quantitative spectroscopic parameters were built up and applied to characterize the organoleptic property of five different commercially available samples including the recently developed Rebaudioside M isoform. Raman spectroscopy was confirmed as a versatile analytical technique that could be used for quantitative quality control tasks on the production line and for prompt in situ characterizations of purchased products. Full article

Plants in riparian areas are well known for their beneficial functions such as providing biodiverse habitats, maintaining water quality, and stabilizing streambanks. However, riparian plants are declining in semi-arid environments due to long-term drought, a decline in groundwater table, and an increase in soil salinity. A new technique using clinoptilolite zeolite (CZ) as a wicking material with minimum artificial irrigation to grow desert willow [Chilopsis linearis (Cav.) Sweet] under field conditions is introduced; desert willow is native to riparian regions of the southwestern United States. For this study’s experiment, desert willow seedlings were planted in boreholes filled with clinoptilolite zeolite (CZ) as a substrate and in situ riparian sandy loam soil (RS) as a control. The boreholes extended to the groundwater table at two distinctive depths, shallow (avg. depth = 1.21 m) and deep (avg. depth = 2.14 m). The plants’ viability was then assessed by measuring their midday water potential (Ψ_md) as an indicator of water stress. There was no significant difference in Ψ_md (p > 0.05) between the plants grown in CZ and RS (mean Ψ_md = −0.91 vs. −0.81 MPa) where the groundwater was shallow and a significant difference (mean Ψ_md = −0.75 vs. −2.03 MPa) where the groundwater was deep. The proposed method is promising as an alternative method for growing desert willow or other plants for riparian rehabilitation with no artificial irrigation. However, its effectiveness depends on groundwater being accessible at the base of the boreholes used for planting. Full article

Cymbidium is an economically important genus in the orchid family (Orchidaceae) that has a pronounced medicinal and ornamental value. Medicinally, the plant is employed as a tonic to treat weakness in chronic diseases, dizziness, eye problems, burns, and wounds, etc. Cymbidiums are highly prized for their graceful flowers and sweet fragrance and are among the top ten most popular cut flowers. They are one of the most important commercial orchid groups and account for 3% of cut flowers in floriculture. Some orchid species in this genus are particularly threatened by excessive harvesting, so conservation measures are needed. Several enthusiastic organizations (e.g., The Cymbidiums Society of America, The Cymbidiums Club in Australia, The Golden Gate Cymbidiums Society, Alameda, CA, etc.) are dedicated to propagating, conserving, promoting, appreciating, and disseminating information about these beautiful and charming orchids. Through organogenesis (direct and indirect) and somatic embryogenesis, extensive propagation techniques for Cymbidiums have been developed to create protocols for synthetic seed production leading to large-scale propagation and long-term ex situ and in vitro conservation. This review highlights the medicinal uses, flower trade, conservation, and massive propagation techniques of Cymbidium orchids. Full article

Agrometeorological models are great tools for predicting yields and improving decision-making. High-quality climatic data are essential for using these models. However, most developing countries have low-quality data with low frequency and spatial coverage. In this case, two main options are available: gathering more data in situ, which is expensive, or using gridded data, obtained from several sources. The main objective here was to evaluate the quality of two gridded climatic databases for filling gaps of real weather stations in the context of developing agrometeorological models. Therefore, a comparative analysis of gridded database and INMET data (precipitation and air temperature) was conducted using an agrometeorological model for sweet orange yield estimation. Both gridded databases had high determination and concordance coefficients for maximum and minimum temperatures. However, higher errors and lower confidence coefficients were observed for precipitation data due to their high dispersion. BR-DWGD indicated more accurate results and correlations in all scenarios evaluated in relation to NasaPower, pointing out that BR-DWGD may be better at filling gaps and providing inputs to simulate attainable yield in the Brazilian citrus belt. Nevertheless, due to the BR-DWGD database’s geographical and temporal limitations, NasaPower is still an alternative in some cases. Additionally, when using NasaPower, it is recommended to use a measured precipitation source to improve prediction quality. Full article

Oil spills at sea, such as the Deepwater Horizon incident in 2010, are devastating environmental hazards, especially for biodiversity in the maritime ecosystem. In order to help the restoration of coastlines, it is critical to clean the oil up quickly and efficiently with various measures, such as the use of barriers, skimmers, sorbents, dispersing agents, in situ burning, and biological agents. However, most of them still cause high remediation costs; are inefficient, non-reusable, and not environmentally friendly; lack a convenient desorption method; or are simply not yet ready to use in a real-case scenario, where high amounts of hydrocarbons must be removed. Therefore, in this work, a reusable modified polyurethane foam for oil absorption on the sea surface is presented and characterised. Due to a chemical formulation with a special co-polymer, its oleophilic properties are strongly enhanced. Laboratory soaking tests with different oils and a mixture of Louisiana sweet crude oil with artificial sea water (ASW) are conducted. To do so, a pneumatic press with adjustable pressures was used to characterise the foam’s capability to recover oil between 10 and 18 times its own weight for a period of up to 50 consecutive repetitions with a maximum saturation in less than one minute. Sequential trials with different oil mass fractions in ASW determined a decreasing content of recovered ASW with increasing amounts of crude oil, while, in all cases, the total oil recovery rate proved to be more than 90% within one’s standard deviation. Finally, practical applications of sorption methods are presented to give an idea of difficulties encountered in real remediation scenarios. Full article

In this work, we present a grazing incidence X-ray diffraction study of the surface of a 0.24Pb(In_1/2Nb_1/2)O₃-Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (PIN-PMN-PT) [011] poled rhombohedral single crystal. The near surface microstructure (the top several tens to hundreds of unit cells) was measured in situ under an applied electric field. The strains calculated from the change in lattice parameters have been compared to the macroscopic strain measured with a strain gauge affixed to the sample surface. The depth dependence of the electrostrain at the crystal surface was investigated as a function of temperature. The analysis revealed hidden sweet spots featuring unusually high strains that were observed as a function of depth, temperature and orientation of the lattice planes. Full article