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The influence of altering rice photorespiration on yield in future climate conditions: will adaptations maintain worthwhile?

Vogel, Jantien (2019) The influence of altering rice photorespiration on yield in future climate conditions: will adaptations maintain worthwhile? Bachelor's Thesis, Biology.

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Yield increases are needed to meet the increasing demand for food of the growing human population. One of the crops of which yield increases are needed is Oryza sativa (rice), whereas a large part of the human population relies on this crop for a large percentage of their caloric intake. The C3 photosynthetic metabolism of rice is considered inefficient due to high photorespiration rates, caused by the tropical climate in which rice crops are commonly cultivated. In photorespiration, the enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) reacts with oxygen instead of carbon dioxide, which is used in the photosynthetic reaction, resulting in carbon losses through the release of CO2. Research focusses both on reducing the photorespiration rate through altering the glycolate pathway in photorespiration, and converting rice into a plant with a C4 metabolism. Altering the glycolate pathway results in the release of CO2 in the chloroplast, resulting in decreased rates of photorespiration and prevention of carbon losses. Furthermore, alternated pathways result in a decrease of energy losses through efficiency improvements of the cycle. In C4 plants, Rubisco is prevented from oxidation by a carbon-concentrating mechanism, causing extensive reduction of photorespiration. The process of C4 photosynthesis is more energy intensive compared to C3, but in the case of rice the energy losses due to photorespiration are higher. In current conditions, these adaptations would increase the yields of rice crops compared to the native C3 metabolism. However, climate projections indicate great increases in atmospheric CO2 levels and temperature, which has been projected to influence these yield increasing strategies and the native photosynthetic metabolism. Projections based on the expected changes in temperature and atmospheric CO2 increase indicate that the native C3 metabolism in rice will gain significantly in efficiency in future conditions, which is confirmed by the majority of experimental research. C4 rice yield is not expected to increase under future conditions, because photosynthesis in C4 plants is not affected significantly by these abiotic factors. The yield of C4 crops is even expected to decrease due to smaller crop duration time. There will still be potential for the altered glycolate pathway in photorespiration of rice, because the advantages of this pathway will remain. Focusing on the facilitation of alternated glycolate pathways in rice will therefore remain relevant, whereas the creation of C4 rice will not be very effective in realizing the aim of increasing yield.

Item Type: Thesis (Bachelor's Thesis)
Supervisor nameSupervisor E mail
Degree programme: Biology
Thesis type: Bachelor's Thesis
Language: English
Date Deposited: 18 Jul 2019
Last Modified: 19 Jul 2019 09:50

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