2019 Year 12 IB Extended Essays

region of low solute concentration (the plant) to a region of high solute concentration (the soil).

Current issues that Australian farmers face regarding Salinity: Salinity affects a large number of Australia’s farmers with over 5.7 million hectares of land being potentially susceptible to developing saline soil (Abs.gov.au, 2010) with regions like the Murray Basin demonstrating salinity levels as high as 16g/L in the water (Rengasamy, 2016). This significantly affects Australia’s economy as Agriculture is responsible 12% of Australia’s Gross Domestic Product and if this industry began to fail, 300,000 Australians would unemployed. Hence a viable, cost-efficient method of irrigation must be developed, as the ground water that is available contains toxic levels of salt, preventing farmers from growing their produce (WorldAtlas, 2018). While use of greywater in small scale domestic application has become common, little research has been done on a large-scale greywater use for agriculture, this report aims to bridge this gap Transportation mechanisms used within plants: Plants generally use a range of different transportation mechanisms that are embedded in the plasma membrane of the plant serving to move ions and other molecules within and around a plant through the use of proton pumps and the use of co-transporters and anti- transporters. How does salinity affect plant growth? All plants rely on osmosis to move water from the soil to the roots and to the rest of the plant. But when the solute concentration within the soil is higher than in the plant, there is a high possibility that the water will move from the plant to the soil (due to osmosis). This causes the plant to become dehydrated, causing their cells plasmolyse, leading to their death (Qld.gov.au, 2013) (Lacoma, 2018).

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