Top Of Canopy Research Articles

Damage potential and control of the common mormon butterfly, Papilio polytes Cramer on citrus

Studies were conducted to know the damage potential and effect of insecticides on leaf area feeding and larval mortality of the common Mormon butterfly, Papilio polytes Cramer in the homestead garden and germplasm center of the Patuakhali Science and Technology University (PSTU) campus and in the laboratory, Department of Entomology, PSTU, Patuakhali, Bangladesh during October to December 2016. Ten Citrus host plants such as Kagoji lime-BAU-1, BAU-2, BAU-3, BAU-4, BARI kagoji, elachi lime, sweet orange, orange, jamir and pumelo were used as study materials. To determine the effects of insecticides on leaf area feeding and larval mortality, five treatments viz., T1 = Voliam flexi 300SC @ 0.5 ml/l of water, T2 = Voliam flexi 300SC @ 1.0 ml/l of water T3 = Bioneem Plus @ 0.5 ml/l of water, T4 = Bioneem Plus @ 1.0 ml/l of water T5 = control were applied. Under natural field conditions, the highest percentage of leaf infestation was recorded in orange, followed by BAU-3, BAU-4, malta and elachi lime, while the lowest percentage was in BARI kagoji on 23 and 30 November, 2016. At the top canopy, the highest percentage of leaf infestation was recorded in orange and elachi (56%), while the lowest was in BAU-4 (8%). At the middle canopy, the highest percentage of leaf infestation was recorded in orange (56%), while the lowest was in jambura (12%). At the lower canopy, the highest percentage of leaf infestation was recorded in BAU-3 (40%), while the lowest was in elachi (8%). At the top canopy, significantly the highest percentage of infested leaves per branch was observed in orange (51.39%) and the lowest percentage of infested leaves per branch was in BAU-4 kagoji lime (10.86%). At middle and lower canopies, no significant difference was observed in the percentage of infested leaves per branch among different citrus varieties. The lowest percentage (6%) of leaf area consumed by 4th instar larva was recorded in T2 (Voliam flexi 300SC @ 1.0 ml/l of water) treated leaf, while the highest percentage of leaf area consumption was found in T5 (control) at 3 HAT. The highest percent mortality (100%) of larvae was found in T2 treated citrus plant, while the lowest percent mortality was in the T3 (70%) treated plant. No mortality was recorded in the untreated control (T5) plant.
 J. Asiat. Soc. Bangladesh, Sci. 47(1): 35-46, June 2021

A case study of a gravity wave induced by Amazon forest orography and low level jet generation

We investigated the role of turbulent coherent structures (CS), gravity waves (GW) and low-level jet (LLJ) propagation in the flow dynamics of the Nocturnal Boundary Layer (NBL) within and above a forest canopy at the Amazon Tall Tower Observatory (ATTO), in Central Amazon. Seven levels of wind velocity and temperature measurements allowed the study of the flow structure below and above the surface layer. We analyzed one dynamically rich night in 2015, which includes three distinct periods. In the first one, the NBL is characterized by CS generated at the canopy top. In the second period, the change in wind direction triggers the onset of a orographic GW above the roughness sublayer. The wave, suppressing the propagation of CS, strongly influences the boundary layer structure, both above and below the canopy. In the third period, low turbulence intensity at the canopy top enables the development of a LLJ. As the jet shear layer propagates upward, it disrupts the wave oscillations, while LLJ dominates the flow dynamics. The wavelet analyses identified i) turbulent and non-turbulent structures with different length and time-scales; ii) coupling of the flow at different levels and the vertical propagation of turbulent and wave motions; and iii) the ability of turbulent and low frequency processes associated with the orographic GW to penetrate within the canopy. Further, scalar measurements of methane, carbon monoxide and carbon dioxide identified the LLJ nose as upward limit for how far scalars can be transported.

Simulation on the impacts of tree canopy morphology on thermal comfort at the pedestrian level

To explore the role of tree canopy morphology on the urban thermal environment and human comfort, this paper considers the variation of four factors (Top Canopy Height (TCH), Leaf Area Density (LAD), Bottom Canopy Height (BCH) and Canopy Diameter (CD)) and uses an orthogonal experiment method (OEM) to build 25 simulation scenarios. In an idealized model planted with trees, the effects of changes in canopy morphological parameters on air temperature and Physical Equivalent Temperature (PET) at a pedestrian height of 1.5m are simulated and discussed using ENVI-met software. The results show that the air temperatures for 25 different groups differed significantly during the day and less at night. At the hottest time of the day (15:00), there was a difference of 7.8°C between the coolest (ID 11) and hottest (ID 16) groups. TCH, LAD and CD are all negatively correlated with PET, while the BCH is positively correlated with PET. Among the four canopy morphology parameters, CD has the most significant effect on PET at a pedestrian level of 1.5m.

Eco-physiological response, water productivity and fruit quality of sweet cherry trees under high tunnels

It is known that high tunnels modify sweet cherry physiological and agronomical response; however, horticultural practices such as irrigation have usually not been adapted to this cultivation system because there is no information about the effects of sweet cherry growing under this controlled environment on fruit tree water relations, water productivity and the possibility of saving water. The present work aims to assess the positive and negative impacts of irrigation regime and protective cultivation on tree water status, agronomical and physiological responses of the sweet cherry tree combination ‘Santina’/‘Colt’ in Mediterranean dry weather conditions of Central Valley of Chile. Two treatments were imposed, plastic covered trees under multi-bay high tunnels and uncovered trees under open field conditions. Within each environment, two irrigation treatments were assayed, a conventional treatment, which followed growers’ normal irrigation practices in the region, and a reduced irrigation treatment, which was irrigated the 75 % of the conventional treatment. High tunnel increased maximum air temperature, relative humidity and altered light radiation in relation to the environmental conditions in the open. Overall, trees under high tunnel showed higher values of soil matric potential, midday stem water potential (-0.8 MPa) and stomatal conductance (250 mmol m−2 s−1). In the open, trees under reduced irrigation showed soil matric potential values below -150 kPa. Thus, soil water deficit affected tree water status, decreased vegetative growth and fruit size. Covered trees blossomed 7 d earlier than those in the open and were harvested 10 d earlier. Total tree yield did not show significant differences among treatments (11.9 kg tree−1); however, when the tree was divided into bottom and top canopy layers, it was found that the top layer of covered trees resulted in significantly lower yield. The cherries from the covered trees were significantly larger (10.4 g) and less firm (75 Durofel units) than those from uncovered trees (8.4 g and 82 Durofel units). The reduced irrigation strategy did not negatively affect tree yield or fruit quality of covered trees and increased water productivity compared with those irrigated with the conventional irrigation. The results obtained highlighted the possibility of decreasing the irrigated water applied to sweet cherry trees under high tunnels by 25 % compared to conventional irrigation.

Numerical simulation of the effects of canopy properties on airflow and pollutant dispersion in street canyons

The air flow and pollutant concentration fields in a street canyon affected by trees could affect the comfort and health of residents. At present, the description of the non-uniform/discontinuous distribution of leaves is difficult. In this study, the leaf distribution in the canopy was characterized by establishing non-continuous (uniform/random) algorithm based on a numerical simulation method, and the effects of canopy properties including, height, porosity and uniform/random leaf distribution, on the airflow and pollutant concentration fields in urban street canyons were investigated. The position of the tree canopy was found to directly affect the airflow field form and the air velocity distribution in the street canyon at low inflows. The average air velocity in the street canyon could be reduced significantly when the top of the tree canopy is near the top of the street canyon. The air velocity and pollutant concentration in the street canyon would vary only slightly due to the canopy porosity. Due to the increasing canopy porosity, the air velocity would increase, and the pollutant concentration would be reduced. The leaves are non-continuous and uniformly distributed at constant porosity, which does not significantly change the velocity distribution and pollutant concentration in the street canyon.

Spectroscopic Estimation of N Concentration in Wheat Organs for Assessing N Remobilization Under Different Irrigation Regimes.

Nitrogen (N) remobilization is a critical process that provides substantial N to winter wheat grains for improving yield productivity. Here, the remobilization of N from anthesis to maturity in two wheat cultivars under three irrigation regimes was measured and its relationship to organ N concentration was examined. Based on spectral data of organ powder samples, partial least squares regression (PLSR) models were calibrated to estimate N concentration (Nmass) and validated against laboratory-based measurements. Although spectral reflectance could accurately estimate Nmass, the PLSR-based Nmass-spectra predictive model was found to be organ-specific, organs at the top canopy (chaff and top three leaves) received the best predictions (R2 > 0.88). In addition, N remobilization efficiency (NRE) in the top two leaves and top third internode was highly correlated with its corresponding N concentration change (ΔNmass) with an R2 of 0.90. ΔNmass of the top first internode (TIN1) explained 78% variation of the whole-plant NRE. This study provides a proof of concept for estimating N concentration and assessing N remobilization using hyperspectral data of individual organs, which offers a non-chemical and low-cost approach to screen germplasms for an optimal NRE in drought-resistance breeding.

Field study on flow structures within aquatic vegetation under combined currents and small‐scale waves

AbstractField measurements were conducted to study the influence of aquatic vegetation on flow structures in floodplains under combined currents and wind‐driven waves. Wave and turbulent velocities were decomposed from the time series of instantaneous velocity and analysed separately. In the present study, the wind waves were small, leading to the ratios of wave excursion (Ew) to stem spacing (S) for all cases tested here were less than 0.5. This caused the vertical distributions of time‐averaged velocity (Uhoriz) and turbulent kinetic energy (TKE) impacted by vegetation similar with the vegetated flow structures under pure current conditions. For emergent vegetation, Uhoriz and TKE distributed uniformly through the entire water column or increased slightly from bed to water surface. Similar distributions were present in the lower part of submerged vegetation. In the upper part of submerged vegetation, Uhoriz and TKE increased rapidly toward water surface and TKE reached its maximum near the top of vegetation. The measured wave orbital velocity (Uw) fitted linear wave theory well through the entire water depth for both the emergent and submerged cases, so that with small Ew/S the wave velocity was not attenuated within vegetation and Uw within canopy can be predicted by the linear wave theory under combined currents and waves. However, wind‐driven waves made the turbulence generated near the top of canopy penetrate a deeper depth into vegetation than predictions under pure current conditions.

Mapping multi-layered mangroves from multispectral, hyperspectral, and LiDAR data

Understanding species distribution and canopy structure of mangrove forests is imperative for flora and fauna conservation in mangrove habitats. However, most mangrove studies focused on the top canopy layer without exploring the vertical structure of mangroves. This paper presents multi-layered mangrove mapping which considered both overstory and understory detection and species classification using multispectral WorldView-3 (WV-3) data, airborne hyperspectral images (HSI), and LiDAR point cloud. First, LiDAR returns were stratified into the overstory and understory by analyzing the profile of return height, which helped understand the vertical structure of the mangrove stands. Second, three classification algorithms Random Forest (RF), Support Vector Machine (SVM), and Convolutional Neural Network (CNN) were compared by applying WV-3, HSI, LiDAR data, and their combinations to map seven vegetative species. Feature selection was conducted to identify important features and the optimal feature size prior to classification tasks. The measured and estimated understory canopy heights reached a high correlation coefficient of 0.71, which demonstrated the effectiveness of using LiDAR data and the proposed procedure to stratify multi-layered canopies. The combined HSI and LiDAR data produced satisfactory results by the three classifiers with overall accuracy (OA) varying from 0.86 to 0.88. And the species was also accurately mapped by integrating WV-3 and LiDAR data using both RF and SVM algorithms with OA attaining between 0.84 and 0.86. The results of this study highlight that (1) LiDAR data provided superior information to map the vertical structure of multi-layered mangroves, which provided valuable information to classify single-layered and dual-layered Kandelia obovata with understory beneath; (2) the combination of spectral and LiDAR features improved mangrove species classification; (3) and species mapping results derived from combined datasets appeared to be more influential by LiDAR features when using RF and SVM, but spectral features played a more important role in CNN.

Evaluation of the FluorWPS Model and Study of the Parameter Sensitivity for Simulating Solar-Induced Chlorophyll Fluorescence

Solar-induced chlorophyll fluorescence (SIF) has been used as an indicator for the photosynthetic activity of vegetation at regional and global scales. Canopy structure affects the radiative transfer process of SIF within canopy and causes the angular-dependencies of SIF. A common solution for interpreting these effects is the use of physically-based radiative transfer models. As a first step, a comprehensive evaluation of the three-dimensional (3D) radiative transfers is needed using ground truth biological and hyperspectral remote sensing measurements. Due to the complexity of forest modeling, few studies have systematically investigated the effect of canopy structural factors and sun-target-viewing geometry on SIF. In this study, we evaluated the capability of the Fluorescence model with the Weighted Photon Spread method (FluorWPS) to simulate at-sensor radiance and SIF at the top of canopy, and identified the influence of the canopy structural factors and sun-target-viewing geometry on the magnitude and directional response of SIF in deciduous forests. To evaluate the model, a 3D forest scene was first constructed from Goddard’s LiDAR Hyperspectral and Thermal (G-LiHT) LiDAR data. The reliability of the reconstructed scene was confirmed by comparing the calculated leaf area index with the measured ones from the scene, which resulted in a relative error of 3.5%. Then, the performance of FluorWPS was evaluated by comparing the simulated at-sensor radiance spectra with the spectra measured from the DUAL and FLUO spectrometer of HyPlant. The radiance spectra simulated by FluorWPS agreed well with the measured spectra by the two high-performance imaging spectrometers, with a coefficient of determination (R2) of 0.998 and 0.926, respectively. SIF simulated by the FluorWPS model agreed well with the values of the DART model. Furthermore, a sensitivity analysis was conducted to assess the effect of the canopy structural parameters and sun-target-viewing geometry on SIF. The maximum difference of the total SIF can be as large as 45% and 47% at the wavelengths of 685 nm and 740 nm for different foliage area volume densities (FAVDs), and 48% and 46% for fractional vegetation covers (FVCs), respectively. Leaf angle distribution has a markedly influence on the magnitude of SIF, with a ratio of emission part to SIF range from 0.48 to 0.72. SIF from the grass layer under the tree contributed 10%+ more to the top of canopy SIF even for a dense forest canopy (FAVD = 3.5 m−1, FVC = 76%). The red SIF at the wavelength of 685 nm had a similar shape to the far-red SIF at a wavelength of 740 nm but with higher variability in varying illumination conditions. The integration of the FluorWPS model and LiDAR modeling can greatly improve the interpretation of SIF at different scales and angular configurations.

Biodiversity facets affect community surface temperature via 3D canopy structure in grassland communities

AbstractCanopy structure is an important driver of the energy budget of grassland ecosystem and is, at the same time, altered by plant diversity. Diverse plant communities typically have taller and more densely packed canopies than less diverse communities. With this, they absorb more radiation, have a higher transpiring leaf surface and are better coupled to the atmosphere which leads to cooler canopy surfaces. However, whether plant diversity generally translates into a cooling potential remains unclear and lacks empirical evidence. Here, we assessed how functional identity, functional diversity and species richness of grassland communities in the Jena Experiment predict the mean and variation of plant surface temperature mediated via effects of canopy structure.Using terrestrial laser scanning, we estimated canopy structure describing metrics of vertical structure (mean height, LAI), the distribution (evenness) and the highest allocation (centre of gravity) of biomass along height strata. As metrics of horizontal structure, we considered community stand gaps, canopy surface variation and emergent flowers. We measured surface temperature with a thermal camera. We used SEM models to predict biodiversity effects on the surface temperature during two seasonal peaks of biomass.Before the first cut in May, herb‐dominated communities directly promoted lower leaf surface temperatures. However, communities with lower centre of gravity (mostly herb dominated) also increased canopy surface temperatures compared with grass‐dominated communities with higher biomass stored in the top canopy. Grass‐dominated communities showed a smaller variation of surface temperatures, which was also positively affected by species richness via an increase in mean height. In August, mean surface temperature decreased with increasing community CC and LAI. The variation of surface temperature was greater in herb‐dominated than in grass‐dominated communities and increased with plant species richness (direct effects).Synthesis. The mean and variation of canopy surface temperature were driven by differences in functional group composition (herbs‐ vs. grass dominance) and to a lesser extent by plant diversity. These effects were partly mediated the metrics of canopy structure but also by direct effects unrelated to the structural metrics considered.

Lianas do not reduce tree biomass accumulation in young successional tropical dry forests.

Young successional tropical forests are crucial in the global carbon cycle because they can quickly sequester large quantities of atmospheric carbon. However, lianas (woody vines) can significantly decrease biomass accumulation in young regenerating forests. Lianas are abundant in tropical dry forests, and thus we hypothesized that lianas reduce biomass accretion in dry forests. Lianas may be particularly detrimental to the growth of young trees, which are vulnerable to competition from lianas. Alternatively, lianas may have a stronger negative effect on the largest trees because lianas seek the high-light environment at the top of the forest canopy. We tested these hypotheses using a liana-removal experiment in 13 dry forest stands that ranged from 1 to 70years in southwestern Panama. We measured biomass accumulation annually for more than 10,000 stems from 2013 to 2017. Contrary to our expectations, liana removal had no effect on tree biomass accumulation across our successional forests and throughout our study period. Liana removal did not benefit smaller trees or larger trees. Lianas did not increase biomass accumulation on recruits, and did not increase biomass loss due to mortality. Surprisingly, removing lianas had a negative effect on three out of 41 tree species. Lianas had no effect on biomass accumulation and loss, possibly because: (1) trees allocated resources to roots instead of stems, (2) trees and lianas partitioned water, (3) higher irradiance after liana removal reduced soil moisture, or (4) low water availability might have been such a strong stressor that it reduced plant-plant competition.

Vapor plumes in a tropical wet forest: spotting the invisible evaporation

Abstract. Forest evaporation exports a vast amount of water vapor from land ecosystems into the atmosphere. Meanwhile, evaporation during rain events is neglected or considered of minor importance in dense ecosystems. Air convection moves the water vapor upwards leading to the formation of large invisible vapor plumes, while the identification of visible vapor plumes has not yet been studied. This work describes the formation process of vapor plumes in a tropical wet forest as evidence of evaporation processes happening during rain events. In the dry season of 2018 at La Selva Biological Station (LSBS) in Costa Rica it was possible to spot visible vapor plumes within the forest canopy. The combination of time-lapse videos at the canopy top with conventional meteorological measurements along the canopy profile allowed us to identify the driver conditions required for this process to happen. This phenomenon happened only during rain events. Visible vapor plumes during the daytime occurred when the following three conditions are accomplished: presence of precipitation (P), air convection, and a lifting condensation level value smaller than 100 m at 43 m height (zlcl.43).

ICOR Atmospheric Correction on Sentinel-3/OLCI over Land: Intercomparison with AERONET, RadCalNet, and SYN Level-2

To validate the iCOR atmospheric correction algorithm applied to the Sentinel-3 Ocean and Land Color Instrument (OLCI), Top-of-Atmosphere (TOA) observations over land, globally retrieved Aerosol Optical Thickness (AOT), Top-of-Canopy (TOC) reflectance, and Vegetation Indices (VIs) were intercompared with (i) AERONET AOT and AERONET-based TOC reflectance simulations, (ii) RadCalNet surface reflectance observations, and (iii) SYN Level 2 (L2) AOT, TOC reflectance, and VIs. The results reveal that, overall, iCOR’s statistical and temporal consistency is high. iCOR AOT retrievals overestimate relative to AERONET, but less than SYN L2. iCOR and SYN L2 TOC reflectances exhibit a negative bias of ~−0.01 and −0.02, respectively, in the Blue bands compared to the simulations. This diminishes for RED and NIR, except for a +0.02 bias for SYN L2 in the NIR. The intercomparison with RadCalNet shows relative differences < ±6%, except for bands Oa02 (Blue) and Oa21 (NIR), which is likely related to the reported OLCI “excess of brightness”. The intercomparison between iCOR and SYN L2 showed R2 = 0.80–0.93 and R2 = 0.92–0.96 for TOC reflectance and VIs, respectively. iCOR’s higher temporal smoothness compared to SYN L2 does not propagate into a significantly higher smoothness for TOC reflectance and VIs. Altogether, we conclude that iCOR is well suitable to retrieve statistically and temporally consistent AOT, TOC reflectance, and VIs over land surfaces from Sentinel-3/OLCI observations.

Mapping forest leaf area density from multiview terrestrial lidar

Abstract Terrestrial lidar data are known to be useful for estimating the three‐dimensional (3D) distribution of leaf area in forests. This type of product holds great potential for modelling canopy reflectance and light interception to study the links between structure and function. However, little is currently known about its potential and limits in dense forests. Higher leaf area density implies that more laser pulses emitted by the ground‐based instrument are intercepted in lower canopy levels, and the implications of such occlusion effects on radiative transfer simulations are unknown. Occlusion effects can be minimized by increasing the number of locations lidar data is acquired from; how many locations are required for a forest with a given structure? This paper aims to address these knowledge gaps. We acquired terrestrial lidar data using a very high density of scanning positions (5 m between positions) over four dense forest 60 m × 60 m plots along a structural gradient. Occlusion effects were quantified, and the 3D distribution of leaf area density was mapped using voxels (cubic volumes) for four different scan densities (one original and three downsampled). The voxel arrays were then input into a radiative transfer model to simulate bidirectional reflectance factors and vertical fraction of absorbed radiation. We found that the summation of leaf area estimates for all voxels within the plot provided leaf area index (LAI) values close to LAI values estimated using traditional methods at each site. Occluded areas occurred mostly at the top of bottom heavy canopies. Radiative transfer simulations suggest that modelling small scale (<1 m) bidirectional reflectance factors (BRF) and light interception requires the highest scan position density used (5 m between scan positions), particularly at bottom heavy sites, and that 10 m between scan positions can be used for plot scale BRF simulations in forests with foliage density and vertical profiles similar to those tested here. This work establishes some initial guidelines for establishing terrestrial lidar survey protocols for mapping leaf area density in forests. The leaf area density voxel arrays derived are among the most accurate plot‐level 3D characterizations of foliage arrangement produced to date.

Beyond the traditional NDVI index as a key factor to mainstream the use of UAV in precision viticulture

In the last decade there has been an exponential growth of research activity on the identification of correlations between vegetational indices elaborated by UAV imagery and productive and vegetative parameters of the vine. However, the acquisition and analysis of spectral data require costs and skills that are often not sufficiently available. In this context, the identification of geometric indices that allow the monitoring of spatial variability with low-cost instruments, without spectral analysis know-how but based on photogrammetry techniques with high-resolution RGB cameras, becomes extremely interesting. The aim of this work was to evaluate the potential of new canopy geometry-based indices for the characterization of vegetative and productive agronomic parameters compared to traditional NDVI based on spectral response of the canopy top. Furthermore, considering grape production as a key parameter directly linked to the economic profit of farmers, this study provides a deeper analysis focused on the development of a rapid yield forecast methodology based on UAV data, evaluating both traditional linear and machine learning regressions. Among the yield assessment models, one of the best results was obtained with the canopy thickness which showed high performance with the Gaussian process regression models (R2 = 0.80), while the yield prediction average accuracy of the best ML models reached 85.95%. The final results obtained confirm the feasibility of this research as a global yield model, which provided good performance through an accurate validation step realized in different years and different vineyards.

Evidence of Chlordecone Resurrection by Glyphosate in French West Indies.

The widespread use of pesticides in agriculture during the last several decades has contaminated soils and different Critical Zone (CZ) compartments, defined as the area extended from the top of the vegetation canopy to the groundwater table, and it integrates interactions of the atmosphere, lithosphere, biosphere, and hydrosphere. However, the long-term fate, storage, and transfer dynamics of persistent pesticides in CZ in a changing world remain poorly understood. In the French West Indies, chlordecone (CLD), a toxic organochlorine insecticide, was extensively applied to banana fields to control banana weevil from 1972 to 1993 after which it was banned. Here, to understand CZ trajectories we apply a retrospective observation based on marine sediment core analyses to monitor long-term CLD transfer, fate, and consequences in Guadeloupe and Martinique islands. Both CLD profiles show synchronous chronologies. We hypothesized that the use of glyphosate, a postemergence herbicide, from the late 1990s onward induced CZ modification with an increase in soil erosion and led to the release of the stable CLD stored in the soils of polluted fields. CLD fluxes drastically increased when glyphosate use began, leading to widespread ecosystem contamination. As glyphosate is used globally, ecotoxicological risk management strategies should consider how its application affects persistent pesticide storage in soils, transfer dynamics, and widespread contamination.

Plant growth and metabolic changes in ‘Super Hot’ chili fruit (Capsicum annuum) exposed to supplemental LED lights

Light-emitting diodes (LEDs) of different colors improve plant growth and increase levels of secondary metabolites. This study aimed to determine the effect of red, blue, and red + blue LEDs (1:1) on the secondary metabolites composition in chili, focusing on capsaicinoids, at the top and middle of the plant canopy in ‘Super Hot’ chili. The accumulated yield of the chili fruit was the highest for control, followed by blue, red and red + blue LEDs, with the top canopy giving twice more yield than the middle canopy. UPLC-MS/MS analysis of chili fruit’s methanolic extracts was used to determine capsaicinoids levels. Blue LEDs significantly increased nordihydrocapsaicin, capsaicin, dihydrocapsaicin, homocapsaicin and homodihydrocapsaicin contents by 57 %, 43 %, 56 %, 28 %, and 54 %, respectively, compared to the control. Also, 24 tentatively annotated metabolites, including phenylalanine, cinnamate, and valine, which are involved in the biosynthesis of capsaicinoids, were semi-quantitatively evaluated to determine the impact of LED exposure on the biosynthetic pathway of capsaicinoids. Supplemental blue LED placed at the top and between the canopy may boost the levels of capsaicinoids in chili fruit grown in greenhouses.

Foliage pests of Marula (Sclerocarya birrea) in Malawi: susceptibility of different provenances

Knowledge of insects’ damage to Agroforestry species is prerequisite prior to promotion of domestication of the species. The study was conducted to assess foliage insect pests in 21 Sclerocarya birrea provenances. Assessment parameters included tolerance levels, tree canopy position of attack, mode of leaf defoliation and type of insect pests responsible for the damage. The results revealed that highly tolerant provenances to leaf defoliation included Kalanga, Magunde, Moamba, and Marracuene. Highly susceptible provenances comprised of Chikwawa, Rumphi, Ntcheu, Missira and Mangochi. Highly significant (P < 0.001) variations existed in tree damage basing on crown position. The top canopy was the most affected followed by the middle and bottom canopies. Leaf damage was found to be significantly (X2 = 4.989, P = 0.026) associated with fruit production, and leaf damaged trees were found to produce three times (Odds Ratio = 3.2) less fruits compared to undamaged tree leaves. The most dominate form of leaf damage was defoliation (43%), followed by skeletonizing (18%). The least leaf damage trees were 37%. Leaf defoliators comprised of two orders namely Coleoptera (beetle) and Lepidoptera (caterpillar). Ceratitis (Pterandrus) capitata (fruit flies) were the most destructive to mature fruits. Although not the primary objective of the study, Ceratitis (Pterandrus) capitata (fruit flies) was identified as the major pest of Marula fruits. Future provenance or progeny trials should be replicated across different ecological areas in order to assess genotype-by-environment interaction effects resulting from differences in leaf flushing period.

Field Performance of a Solid Set Canopy Delivery System Configured for High-Density Tall Spindle Architecture Trained Apple Canopies

HighlightsVariants of a solid set canopy delivery system were evaluated in a high-density apple orchard.A pair of hollow-cone nozzles installed in three tiers had optimum spray performance for studied crop growth stages.A shower-down arrangement of emitters was the simplest design but had lesser deposition on abaxial leaf surfaces.Abstract. Optimally configured solid set canopy delivery system (SSCDS) based spraying has potential to improve tree-fruit crop pest and disease management by reducing application time and eliminating dependence on ground conditions. In such an effort, this study attempted to optimize SSCDS variants. Four different emitter types (E1 to E4) installed in different mounting configurations (C1 to C4) were evaluated for spray deposition and coverage in a high-density apple orchard trained in tall spindle architecture. Emitters E1, E2, and E4 had full circle spray patterns, and E3 had a hollow-cone pattern. Configuration C1 had a pair of E1 emitters spraying in a vertical plane and installed between two trees at 1.5 m above ground level (AGL). Another E1 emitter spraying in a horizontal plane was mounted atop each tree at 3.3 m AGL. Configurations C2 and C4 had emitters (E2 and E4, respectively) mounted atop each tree at 3.3 m AGL, and C3 had a pair of E3 emitters installed in a three-tier arrangement between two trees in the crop row. During field trials, a tree canopy about 3.0 m tall was divided into three zones (0 to 1.4 m, &amp;gt;1.4 to 2.2 m, and &amp;gt;2.2 to 3.0 m AGL) as bottom, middle, and top canopy zones, respectively. Mylar cards were used to quantify spray deposition using fluorometry, and water-sensitive papers (WSPs) were used to quantify coverage using image processing. Configuration C3 with 80° hollow-cone nozzles in a twin-emitter, three-tier arrangement had the highest overall spray deposition (581.1 ±77.8 ng cm-2, mean ± standard error) and coverage (18.4% ±4.1%). Moreover, C3 also had a significantly higher coverage on the abaxial surfaces of leaves compared to the other configurations. Configurations C1 was non-optimal because it lacked abaxial surface coverage as the canopy grew in the middle and late growth stages. Moreover, significant spray runoff from leaf surfaces was observed visually in the middle zone for C1 during the middle and late stages. This may be attributed to canopy growth around the emitters. Configurations C2 and C4, with emitters in a shower-down arrangement, had the highest deposition and coverage in the top canopy zone compared to the middle and bottom zones. Configurations C2 and C4 also had significantly higher spray coverage on the adaxial surfaces of leaves compared to the abaxial surfaces. Overall, despite the complex design of configuration C3 with six emitters per tree, it may be the most ideal arrangement for agrochemical application in an apple orchard trained in tall spindle architecture. For commercial feasibility, we recommend exploring this three-tier SSCDS configuration with low-cost emitter alternatives. Pertinent continuing efforts have been published by our group in which we successfully modified low-cost irrigation emitters, and the resulting three-tier SSCDS configurations had improved spray performance over expensive hollow-cone nozzles. Keywords: Fixed spray system, High-density apple orchard, Solid set canopy delivery system, Spray coverage, Spray deposition, SSCDS.

Coastal Sand Dunes Monitoring by Low Vegetation Cover Classification and Digital Elevation Model Improvement Using Synchronized Hyperspectral and Full-Waveform LiDAR Remote Sensing

Due to the coastal morphodynamic being impacted by climate change there is a need for systematic and large-scale monitoring. The monitoring of sandy dunes in Pays-de-la-Loire (France) requires a simultaneous mapping of (i) its morphology, allowing to assess the sedimentary stocks and (ii) its low vegetation cover, which constitutes a significant proxy of the dune dynamics. The synchronization of hyperspectral imaging (HSI) with full-waveform (FWF) LiDAR is possible with an airborne platform. For a more intimate combination, we aligned the 1064 nm laser beam of a bi-spectral Titan FWF LiDAR with 401 bands and the 15 cm range resolution on the Hyspex VNIR camera with 160 bands and a 4.2 nm spectral resolution, making both types of data follow the same emergence angle. A ray tracing procedure permits to associate the data while keeping the acquisition angles. Stacking multiple shifted FWFs, which are linked to the same pixel, enables reaching a 5 cm range resolution grid. The objectives are (i) to improve the accuracy of the digital terrain models (DTM) obtained from an FWF analysis by calibrating it on dGPS field measurements and correcting it from local deviations induced by vegetation and (ii) in combination with airborne reflectances obtained with PARGE and ATCOR-4 corrections, to implement a supervised hierarchic classification of the main foredune vegetation proxies independently of the acquisition year and the physiological state. The normalization of the FWF LiDAR range to a dry sand reference waveform and the centering on their top canopy echoes allows to isolate Ammophilia arenaria from other vegetation types using two FWF indices, without confusion with slope effects. Fourteen HSI reflectance indices and 19 HSI Spectral Angle Mapping (SAM) indices based on 2017 spectral field measurements performed with the same Hyspex VNIR camera were stacked with both FWF indices into a single co-image for each acquisition year. A simple straightforward hierarchical classification of all 35 pre-classified co-image bands was successfully applied along 20 km, out of the 250 km of coastline acquired from 2017 to 2019, prefiguring its systematic application to the whole 250 km every year.