9 results on '"Burgess, Alexandra Jacquelyn"'
Search Results
2. The variable light environment within complex 3D canopies
- Author
-
Burgess, Alexandra Jacquelyn
- Subjects
581 ,QK710 Plant physiology - Abstract
With an expanding population and uncertain consequences of climate change, the need to both stabilise and increase crop yields is important. The relationship between biomass production and radiation interception suggests one target for improvement. Under optimal growing conditions, biomass production is determined by the amount of light intercepted and the efficiency with which this is converted into dry matter. The amount of light at a given photosynthetic surface is dependent upon solar movement, weather patterns and the structure of the plant, amongst others. Optimising canopy structure provides a method by which we can improve and optimise both radiation interception and also the distribution of light among canopy layers that contribute to net photosynthesis. This requires knowledge of how canopy structure determines light distribution and therefore photosynthetic capacity of a given crop species. The aim of this thesis was to assess the relationships between canopy architecture, the light environment and photosynthesis. This focused on two core areas: the effect of varietal selection and management practices on canopy structure and the light environment and; the effect of variable light on select photosynthetic processes (photoinhibition and acclimation). An image-based reconstruction method based on stereocameras was employed with a forward ray tracing algorithm in order to model canopy structure and light distributions in high-resolution. Empirical models were then applied using parameterisation from manually measured data to predict the effects of variable light on photosynthesis. The plasticity of plants means that the physical structure of the canopy is dependent upon many different factors. Detailed descriptions of canopy architecture are integral to predicting whole canopy photosynthesis due to the spatial and temporal differences in light profiles between canopies. This inherent complexity of the canopy means that previous methods for calculating light interception are often not suitable. 3-dimensional modelling can provide a quick and easy method to retain this complexity by preserving small variations. This provides a means to more accurately quantify light interception and enable the scaling of cellular level processes up to the whole canopy. Results indicate that a canopy with more upright leaves enables greater light penetration to lower canopy layers, and thus higher photosynthetic productivity. This structural characteristic can also limit radiation-induced damage by preventing exposure to high light, particularly around midday. Whilst these features may lead to higher photosynthetic rates per unit leaf area, per unit ground area, photosynthesis is usually determined by total leaf area of the canopies, and within this study, the erect canopies tended to have lower total leaf areas than the more horizontal canopies. The structural arrangement of plant material often led to low levels of light within the lower canopy layers which were punctuated by infrequent, high light events. However, the slow response of photosynthesis to a change in light levels meant that these sun flecks cannot be used by the plant and thus the optimal strategy should be geared towards light harvesting and efficient photosynthesis under low light conditions. The results of this study contribute to our understanding of photosynthetic processes within the whole canopy and provide a foundation for future work in this area.
- Published
- 2017
3. Drones in the Sky: Towards a More Sustainable Agriculture
- Author
-
Arza-García, Marcos, primary and Burgess, Alexandra Jacquelyn, additional
- Published
- 2022
- Full Text
- View/download PDF
4. Drones in the Sky: Towards a More Sustainable Agriculture.
- Author
-
Arza-García, Marcos and Burgess, Alexandra Jacquelyn
- Subjects
SUSTAINABLE agriculture ,AGRICULTURAL remote sensing ,REMOTE sensing ,NATURAL resources ,REMOTE-sensing images ,AGRICULTURAL technology - Abstract
This Special Issue in Agriculture aims to collect state-of-the-art manuscripts related to local-scale applications of UAV-based remote sensing in precision agriculture and horticulture, with a prospective focus on sustainability. Nowadays, with an increasing world population, the production of bio-resources becomes a strategic sector for supporting any sustainable society. Over the past few years, UAVs (Unmanned Aerial Vehicles), RPAs (Remotely Piloted Aircrafts), and drones have emerged in the market, closing the gap between data collected using satellite remote sensing or manned aircraft and ground-based methods. [Extracted from the article]
- Published
- 2023
- Full Text
- View/download PDF
5. Normalized Difference Vegetation Index and Chlorophyll Content for Precision Nitrogen Management in Durum Wheat Cultivars under Semi-Arid Conditions.
- Author
-
Kizilgeci, Ferhat, Yildirim, Mehmet, Islam, Mohammad Sohidul, Ratnasekera, Disna, Iqbal, Muhammad Aamir, Sabagh, Ayman EL, and Burgess, Alexandra Jacquelyn
- Abstract
To impart sustainability to modern intensive farming systems, environmental pollution caused by nitrogenous fertilizers in needs to be reduced by optimizing their doses. To estimate the grain yield and nutrtional quallity of wheat, the normalized difference vegetation index (NDVI) and chlorophyll content (SPAD) are potential screening tools to identify the N deficiency and screen out the promising cultivars. The two-year field study was comprised with five levels of nitrogen (N) (control, 50, 100, 150 and 200 kg N ha
−1 ) and two durum wheat genotypes (Sena and Svevo). The experimental design was split-plot, in which N levels were placed in the main plots, while wheat genotypes were arranged in sub-plots. To predict the yield and quality traits, the NDVI and SPAD values recorded at heading, anthesis and milky growth stages were taken as response variables. The results revealed that N fertilization significantly influenced the SPAD and NDVI attributed traits of durum wheat, except NDVI at milky stage (NDVI-M) during the first year. The maximum value of NDVI was recorded by 150 kg N ha−1 , while control treatment gave the minimum value. The grain yield was increased with the increasing dose of the N up to 100 kg N ha−1 (4121 kg ha−1 ), and thereafter, it was declined with further increased of N levels. However, the variation between the genotypes was not significant, except NDVI and SPAD values at the milky stage. The genotype Svevo had the highest NDVI values at all growth stages, while the genotype Sena recorded the maximum SPAD values during both years. Similarly, the N levels significantly influenced the quality traits (protein, wet gluten, starch test weight and Zeleny sedimentation) of both genotypes. The highly significant relationship of SPAD and NDVI with the grain yield and yield attributes showed their reliability as indicators for determining the N deficiency and selection of superior wheat genotypes for ensuring food security under climate change scenario. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
6. Organic Amendments Boost Soil Fertility and Rice Productivity and Reduce Methane Emissions from Paddy Fields under Sub-Tropical Conditions.
- Author
-
Haque, Md Mahamudul, Datta, Juel, Ahmed, Tareq, Ehsanullah, Md, Karim, Md Neaul, Akter, Mt. Samima, Iqbal, Muhammad Aamir, Baazeem, Alaa, Hadifa, Adel, Ahmed, Sharif, EL Sabagh, Ayman, and Burgess, Alexandra Jacquelyn
- Abstract
Deteriorating soil fertility and gradually decreasing rice productivity along with higher greenhouse gas emissions from paddy fields have emerged as serious threats to the sustainability of rice production and food security. Rice production in the subtropical environment in Bangladesh is mostly dependent on synthetic inorganic fertilizer to maintain productivity; however, the inorganic fertilizer has negative effects on global warming. Climate-smart and resilient agricultural production systems are major concerns nowadays to meet sustainable development goals. The study was conducted to evaluate the optimum rate and source of organic amendments on rice productivity and soil fertility along with CH
4 emission. A total of nine nutrient combinations were used in the study. The CH4 emission, soil redox potential (Eh), soil pH, soil nitrogen and organic carbon, available phosphorus, rice grain and straw were greatly affected by the application of different rates and sources of the nutrient. However, the soil exchangeable K content, plant height, and harvest index were not affected. Among the treatments, the application of 75% recommended fertilizer (RF) + biosolid 2 tha−1 (T3) was the most effective and showed the superior performance in terms of available P (12.90 ppm), the number of grains panicle−1 (121), and 1000-grain weight (24.6g), rice grain, and straw yield along with the moderate CH4 emission (18.25 mg m−2 h−1 ). On the other hand, the lowest soil Eh (−158 mV) and soil pH (6.65) were measured from the treatment T3. The finding of this study revealed that the application of 75% of RF + biosolid 2 t ha−1 can be recommended as the preferable soil amendment for boosting rice yield, reduce CH4 emissions, and sustainably maintain soil fertility. Furthermore, this finding may help to introduce preferable soil amendment doses, which will contribute to boosting rice productivity and economic turnouts of the farmers. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
7. The variable light environment within complex 3D canopies
- Author
-
Burgess, Alexandra Jacquelyn
- Abstract
With an expanding population and uncertain consequences of climate change, the need to both stabilise and increase crop yields is important. The relationship between biomass production and radiation interception suggests one target for improvement. Under optimal growing conditions, biomass production is determined by the amount of light intercepted and the efficiency with which this is converted into dry matter. The amount of light at a given photosynthetic surface is dependent upon solar movement, weather patterns and the structure of the plant, amongst others. Optimising canopy structure provides a method by which we can improve and optimise both radiation interception and also the distribution of light among canopy layers that contribute to net photosynthesis. This requires knowledge of how canopy structure determines light distribution and therefore photosynthetic capacity of a given crop species. \ud \ud The aim of this thesis was to assess the relationships between canopy architecture, the light environment and photosynthesis. This focused on two core areas: the effect of varietal selection and management practices on canopy structure and the light environment and; the effect of variable light on select photosynthetic processes (photoinhibition and acclimation). An image-based reconstruction method based on stereocameras was employed with a forward ray tracing algorithm in order to model canopy structure and light distributions in high-resolution. Empirical models were then applied using parameterisation from manually measured data to predict the effects of variable light on photosynthesis. \ud \ud The plasticity of plants means that the physical structure of the canopy is dependent upon many different factors. Detailed descriptions of canopy architecture are integral to predicting whole canopy photosynthesis due to the spatial and temporal differences in light profiles between canopies. This inherent complexity of the canopy means that previous methods for calculating light interception are often not suitable. 3-dimensional modelling can provide a quick and easy method to retain this complexity by preserving small variations. This provides a means to more accurately quantify light interception and enable the scaling of cellular level processes up to the whole canopy. \ud \ud Results indicate that a canopy with more upright leaves enables greater light penetration to lower canopy layers, and thus higher photosynthetic productivity. This structural characteristic can also limit radiation-induced damage by preventing exposure to high light, particularly around midday. Whilst these features may lead to higher photosynthetic rates per unit leaf area, per unit ground area, photosynthesis is usually determined by total leaf area of the canopies, and within this study, the erect canopies tended to have lower total leaf areas than the more horizontal canopies. The structural arrangement of plant material often led to low levels of light within the lower canopy layers which were punctuated by infrequent, high light events. However, the slow response of photosynthesis to a change in light levels meant that these sun flecks cannot be used by the plant and thus the optimal strategy should be geared towards light harvesting and efficient photosynthesis under low light conditions. \ud \ud The results of this study contribute to our understanding of photosynthetic processes within the whole canopy and provide a foundation for future work in this area.
8. The variable light environment within complex 3D canopies
- Author
-
Burgess, Alexandra Jacquelyn and Burgess, Alexandra Jacquelyn
- Abstract
With an expanding population and uncertain consequences of climate change, the need to both stabilise and increase crop yields is important. The relationship between biomass production and radiation interception suggests one target for improvement. Under optimal growing conditions, biomass production is determined by the amount of light intercepted and the efficiency with which this is converted into dry matter. The amount of light at a given photosynthetic surface is dependent upon solar movement, weather patterns and the structure of the plant, amongst others. Optimising canopy structure provides a method by which we can improve and optimise both radiation interception and also the distribution of light among canopy layers that contribute to net photosynthesis. This requires knowledge of how canopy structure determines light distribution and therefore photosynthetic capacity of a given crop species. The aim of this thesis was to assess the relationships between canopy architecture, the light environment and photosynthesis. This focused on two core areas: the effect of varietal selection and management practices on canopy structure and the light environment and; the effect of variable light on select photosynthetic processes (photoinhibition and acclimation). An image-based reconstruction method based on stereocameras was employed with a forward ray tracing algorithm in order to model canopy structure and light distributions in high-resolution. Empirical models were then applied using parameterisation from manually measured data to predict the effects of variable light on photosynthesis. The plasticity of plants means that the physical structure of the canopy is dependent upon many different factors. Detailed descriptions of canopy architecture are integral to predicting whole canopy photosynthesis due to the spatial and temporal differences in light profiles between canopies. This inherent complexity of the canopy means that previous methods for calculating light
9. The variable light environment within complex 3D canopies
- Author
-
Burgess, Alexandra Jacquelyn and Burgess, Alexandra Jacquelyn
- Abstract
With an expanding population and uncertain consequences of climate change, the need to both stabilise and increase crop yields is important. The relationship between biomass production and radiation interception suggests one target for improvement. Under optimal growing conditions, biomass production is determined by the amount of light intercepted and the efficiency with which this is converted into dry matter. The amount of light at a given photosynthetic surface is dependent upon solar movement, weather patterns and the structure of the plant, amongst others. Optimising canopy structure provides a method by which we can improve and optimise both radiation interception and also the distribution of light among canopy layers that contribute to net photosynthesis. This requires knowledge of how canopy structure determines light distribution and therefore photosynthetic capacity of a given crop species. The aim of this thesis was to assess the relationships between canopy architecture, the light environment and photosynthesis. This focused on two core areas: the effect of varietal selection and management practices on canopy structure and the light environment and; the effect of variable light on select photosynthetic processes (photoinhibition and acclimation). An image-based reconstruction method based on stereocameras was employed with a forward ray tracing algorithm in order to model canopy structure and light distributions in high-resolution. Empirical models were then applied using parameterisation from manually measured data to predict the effects of variable light on photosynthesis. The plasticity of plants means that the physical structure of the canopy is dependent upon many different factors. Detailed descriptions of canopy architecture are integral to predicting whole canopy photosynthesis due to the spatial and temporal differences in light profiles between canopies. This inherent complexity of the canopy means that previous methods for calculating light
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