Search results for "Green leaf"

Evaluation of Sentinel-2 Red-Edge Bands for Empirical Estimation of Green LAI and Chlorophyll Content

2011

ESA’s upcoming satellite Sentinel-2 will provide Earth images of high spatial, spectral and temporal resolution and aims to ensure continuity for Landsat and SPOT observations. In comparison to the latter sensors, Sentinel-2 incorporates three new spectral bands in the red-edge region, which are centered at 705, 740 and 783 nm. This study addresses the importance of these new bands for the retrieval and monitoring of two important biophysical parameters: green leaf area index (LAI) and chlorophyll content (Ch). With data from several ESA field campaigns over agricultural sites (SPARC, AgriSAR, CEFLES2) we have evaluated the efficacy of two empirical methods that specifically make use of the…

Influence of Feeding and Oviposition by Phytophagous Pentatomids on Photosynthesis of Herbaceous Plants

2010

Abstract Feeding by herbivorous insects may change photosynthetic activity of host plants. We studied how feeding and oviposition by herbivorous stink bugs, Murgantia histrionica and Nezara viridula (Heteroptera: Pentatomidae), affect photosynthetic parameters of Brassica oleracea (savoy cabbage) and Phaseolus vulgaris (French bean). First, we measured photosynthetic gas exchange, chlorophyll fluorescence imaging, and emission of induced volatile organic compounds (VOC) immediately after feeding and during a post-feeding period. Photosynthesis decreased rapidly and substantially in B. oleracea and P. vulgaris infested by feeding bugs. Stomatal conductance did not decrease proportionally wit…

Prototyping Sentinel-2 green LAI and brown LAI products for cropland monitoring.

2022

Abstract For agricultural applications, identification of non-photosynthetic above-ground vegetation is of great interest as it contributes to assess harvest practices, detecting crop residues or drought events, as well as to better predict the carbon, water and nutrients uptake. While the mapping of green Leaf Area Index (LAI) is well established, current operational retrieval models are not calibrated for LAI estimation over senescent, brown vegetation. This not only leads to an underestimation of LAI when crops are ripening, but is also a missed monitoring opportunity. The high spatial and temporal resolution of Sentinel-2 (S2) satellites constellation offers the possibility to estimate …

Atmospheric Oxidation Reactions of Methyl Salicylate as Green Leaf Volatiles by OH Radical: Theoretical Kinetics and Mechanism

2020

Multi-Season Phenology Mapping of Nile Delta Croplands Using Time Series of Sentinel-2 and Landsat 8 Green LAI

2022

Space-based cropland phenology monitoring substantially assists agricultural managing practices and plays an important role in crop yield predictions. Multitemporal satellite observations allow analyzing vegetation seasonal dynamics over large areas by using vegetation indices or by deriving biophysical variables. The Nile Delta represents about half of all agricultural lands of Egypt. In this region, intensifying farming systems are predominant and multi-cropping rotations schemes are increasing, requiring a high temporal and spatial resolution monitoring for capturing successive crop growth cycles. This study presents a workflow for cropland phenology characterization and mapping based on…