Results of industrial tests on the LV-130 vertical leaf filter

Annual grasses constitute a major weed problem in winter annual crops in Northern Europe and especially in cropping systems where ploughing is omitted. At the optimum growth stage for control with POST herbicides, grasses have a predominantly vertical leaf orientation. This represents a very difficult spray target using the standard technique where nozzles are mounted more or less vertically downward. In this study, efficacy of the foliar-acting herbicide, haloxyfop, on perennial ryegrass at the two- to three-leaf stage was investigated in field experiments using some alternative configurations of nozzle mounting on the sprayer. Angling the spray either forward or backward relative to the direction of travel increased herbicide efficacy using standard commercially available flat-fan and pre-orifice nozzles. Efficacy increased generally with increasing angling relative to vertically downward and the forward-angled spray improved efficacy most. The largest improvement in efficacy was obtained using a 60° forward-angled spray in combination with a reduced boom height. Using this configuration, herbicide dose could be reduced by approximately 30% without loss of efficacy in comparison with the standard vertical mounting of nozzles. There was no advantage of using combinations of forward- and backward-angled nozzles.

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A Multi-Layer Model for Transpiration of Urban Trees Considering Vertical Structure

Forests ◽

10.3390/f11111164 ◽

2020 ◽

Vol 11 (11) ◽

pp. 1164

Author(s):

Seok Hwan Yun ◽

Chae Yeon Park ◽

Eun Sub Kim ◽

Dong Kun Lee

Keyword(s):

Transpiration Rate ◽

Vertical Structure ◽

Urban Canopy ◽

High Density ◽

Urban Trees ◽

Constant Density ◽

Layer Model ◽

Building Height ◽

Vertical Leaf ◽

Physiological Processes

As the intensity of the urban heat island effect increases, the cooling effect of urban trees has become important. Urban trees cool surfaces during the day via shading, increasing albedo and transpiration. Many studies are being conducted to calculate the transpiration rate; however, most approaches are not suitable for urban trees and oversimplify plant physiological processes. We propose a multi-layer model for the transpiration of urban trees, accounting for plant physiological processes and considering the vertical structure of trees and buildings. It has been expanded from an urban canopy model to accurately simulate the photosynthetically active radiation and leaf surface temperature. To evaluate how tree and surrounding building conditions affect transpiration, we simulated the transpiration of trees in different scenarios such as building height (i.e., 1H, 2H and 3H, H = 12 m), tree location (i.e., south tree and north tree in a E-W street), and vertical leaf area density (LAD) (i.e., constant density, high density with few layers, high density in middle layers, and high density in lower layers). The transpiration rate was estimated to be more sensitive to the building height and tree location than the LAD distribution. Transpiration-efficient trees differed depending on the surrounding condition and plant location. This model is a useful tool that provides guidelines on the planting of thermo-efficient trees depending on the structure or environment of the city.

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Dynamics of Vertical Leaf Nitrogen Distribution in a Vegetative Wheat Canopy. Impact on Canopy Photosynthesis

Annals of Botany ◽

10.1006/anbo.2000.1244 ◽

2000 ◽

Vol 86 (4) ◽

pp. 821-831 ◽

Cited By ~ 71

Author(s):

M Dreccer

Keyword(s):

Leaf Nitrogen ◽

Canopy Photosynthesis ◽

Nitrogen Distribution ◽

Vertical Leaf

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Retrieval of forest vertical leaf area index and clumping index through field measurement and remote sensing techniques: A review

Chinese Science Bulletin (Chinese Version) ◽

10.1360/tb-2020-1057 ◽

2020 ◽

Author(s):

Hongliang Fang

Keyword(s):

Remote Sensing ◽

Leaf Area Index ◽

Leaf Area ◽

Field Measurement ◽

Area Index ◽

Vertical Leaf ◽

Clumping Index ◽

Remote Sensing Techniques

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Suitability of Airborne and Terrestrial Laser Scanning for Mapping Tree Crop Structural Metrics for Improved Orchard Management

Remote Sensing ◽

10.3390/rs12101647 ◽

2020 ◽

Vol 12 (10) ◽

pp. 1647 ◽

Cited By ~ 2

Author(s):

Dan Wu ◽

Kasper Johansen ◽

Stuart Phinn ◽

Andrew Robson

Keyword(s):

Leaf Area ◽

Laser Scanning ◽

Terrestrial Laser Scanning ◽

Tree Structure ◽

Crown Height ◽

Crown Area ◽

Vertical Leaf ◽

Fractional Cover ◽

Crown Volume ◽

Crown Structure

Airborne Laser Scanning (ALS) and Terrestrial Laser Scanning (TLS) systems are useful tools for deriving horticultural tree structure estimates. However, there are limited studies to guide growers and agronomists on different applications of the two technologies for horticultural tree crops, despite the importance of measuring tree structure for pruning practices, yield forecasting, tree condition assessment, irrigation and fertilization optimization. Here, we evaluated ALS data against near coincident TLS data in avocado, macadamia and mango orchards to demonstrate and assess their accuracies and potential application for mapping crown area, fractional cover, maximum crown height, and crown volume. ALS and TLS measurements were similar for crown area, fractional cover and maximum crown height (coefficient of determination (R2) ≥ 0.94, relative root mean square error (rRMSE) ≤ 4.47%). Due to the limited ability of ALS data to measure lower branches and within crown structure, crown volume estimates from ALS and TLS data were less correlated (R2 = 0.81, rRMSE = 42.66%) with the ALS data found to consistently underestimate crown volume. To illustrate the effects of different spatial resolution, capacity and coverage of ALS and TLS data, we also calculated leaf area, leaf area density and vertical leaf area profile from the TLS data, while canopy height, tree row dimensions and tree counts) at the orchard level were calculated from ALS data. Our results showed that ALS data have the ability to accurately measure horticultural crown structural parameters, which mainly rely on top of crown information, and measurements of hedgerow width, length and tree counts at the orchard scale is also achievable. While the use of TLS data to map crown structure can only cover a limited number of trees, the assessment of all crown strata is achievable, allowing measurements of crown volume, leaf area density and vertical leaf area profile to be derived for individual trees. This study provides information for growers and horticultural industries on the capacities and achievable mapping accuracies of standard ALS data for calculating crown structural attributes of horticultural tree crops.

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