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3. Doktoritööd

Selle kollektsiooni püsiv URIhttp://hdl.handle.net/10492/2490

Sirvi

Sirvi 3. Doktoritööd Autor "Abiola, Yusuph Olawale" järgi

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    Changes in plant carbon gain and volatile emissions under elevated CO₂ concentration and heat stress
    (Estonian University of Life Sciences, 2026) Abiola, Yusuph Olawale; Niinemets, Ülo (advisor); Institute of Agriculture and Environmental Sciences; Loreto, Francesco (opponent)
    ABSTRACT. Climate change is reshaping the growth conditions for cultivated crops. Rising atmospheric carbon dioxide (CO₂) levels and increasing temperatures are two major challenges facing plants. Elevated CO₂ can initially boost plant growth by enhancing photosynthesis, but its benefits are not always sustained over the long term, especially when nutrients become limiting. Meanwhile, warmer temperatures impose heat stress that disrupts the plant’s photosynthetic machinery and overall productivity. In response, plants release natural chemicals called volatile organic compounds (VOCs) that help in stress defense and communication with their environment. This thesis investigated the impacts of increased CO₂ and heat stress, both individually and in combination, on plant carbon gain and VOC emissions in tropical fruit trees, avocado (Persea americana) and soursop (Annona muricata), as well as the Mediterranean herb, oregano (Origanum vulgare). In avocado, elevated CO₂ improved growth and enhanced recovery after heat stress, especially in young leaves. In contrast, soursop responded differently: elevated CO₂ declined photosynthetic performance and growth due to internal limitations that reduced their ability to convert carbon into growth. Heat stress consistently impaired photosynthesis mainly through internal biochemical limitations rather than stomatal closure. In oregano, prior exposure to mild heat (heat priming) improved tolerance to subsequent severe heat. Heat stress also triggered strong emissions of volatile compounds that protect plant cells and signal stress. Overall, this thesis shows that plant resilience to climate change depends on species-specific traits, developmental stage, and prior stress exposure. These findings improve our understanding of how to predict crop performance under changing environmental conditions and support the development of plant varieties better adapted to both current and future climates.