Skyline system for photosynthetic crop phenotyping

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Plants capture energy from sunlight and use this to fix carbon dioxide, producing the carbohydrates that we eat. Although we have selected and bred crop plants for hundreds of years, their performance is still not optimal. By improving photosynthesis, or maintaining photosynthetic rates in the face of stresses (e.g. pests and pathogens, drought, extremes of temperature), we can increase food security to address the concerns of rising world populations and losses due to climate change.The emerging field of plant phenomics seeks to make high-throughput measurements of plant structure and function over time. Whilst great advances have been made using drones and robots to measure the structure and pigmentation of plants using specialised cameras, measuring photosynthesis is much more challenging. The 'gold standard' for measuring photosynthesis is gas exchange, where we can measure carbon dioxide taken up by the leaves and water loss through small pores known as stomata. This requires leaves to be clamped in an air-tight chamber, which is time consuming and doesn't capture the variation in the environment and subsequent changes in photosynthetic rates that occur throughout the day, or from day-to-day as the weather changes. It also only measures a small part of the leaf rather than the whole plant canopy.In this project we will deploy a 'Skyline' system that allows gas exchange measurements to be made automatically, from the whole crop canopy, multiple times per day. The system uses a cradle that runs along a pair of cables that can automatically lower a chamber onto plants and capture gas exchange. This will allow us to capture a true picture of photosynthesis in crops in the field (or protected environments such as greenhouses) over the course of a growing season. Whenever a measurement is taken, an image is also captured using a multispectral camera, of the sort normally deployed by drone. This will enable us to accurately correlate true measurements of photosynthetic rate made using the Skyline system with high-throughput imaging approaches that can be deployed on a much larger scale by drones. Making these correlations is particularly important when plants are modified in some way or are subject to stresses such as disease. In this project we will test the system in a protected environment to see how plants which have been genetically modified to improve photosynthetic rate perform in a fluctuating environment over an extended period. We will also look at conventional wheat varieties that, in the laboratory, show different responses to the important pathogen, Septoria tritici,to see whether these differences are maintained in the field, preserve photosynthetic rates and ultimately yield. This approach is essential in translating laboratory based research into the field and ultimately, improving the UK's food security.The system will also be made accessible to the wider UK plant phenomics and crop breeding communities as part of PhenomUK-RI - a new project that addresses how the UK can exploit the developing field of plant phenomics to improve agriculture.