Increased salinity negatively affects plant germination by reducing osmotic potential, limiting germination percentage and rate, and inhibiting root development. It also leads to ion toxicity and oxidative stress.
Here's a more detailed explanation:
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Reduced Osmotic Potential: Salinity increases the salt concentration in the soil, which in turn lowers the osmotic potential. This makes it more difficult for plants to absorb water, as water moves from areas of high water potential (low salt concentration) to areas of low water potential (high salt concentration). Reduced water uptake inhibits germination.
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Decreased Germination Percentage and Rate: The increased osmotic stress caused by salinity inhibits the seed's ability to absorb the water needed for germination. As a result, fewer seeds germinate (lower germination percentage), and those that do germinate take longer to do so (slower germination rate).
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Inhibited Root Development: Salinity negatively impacts root growth. The high salt concentration can be toxic to root cells, hindering their development and elongation. Poor root development further reduces the plant's ability to absorb water and nutrients, exacerbating the effects of salinity stress.
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Ion Toxicity: Excessive accumulation of specific ions like sodium (Na+) and chloride (Cl-) in plant tissues leads to ion toxicity. This can disrupt cellular processes, damage cell membranes, and inhibit enzyme activity, ultimately affecting germination and early seedling growth.
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Oxidative Stress: Salinity can induce oxidative stress in plants. This occurs when there's an imbalance between the production of reactive oxygen species (ROS) and the plant's ability to neutralize them. ROS can damage cellular components and interfere with germination processes.
In summary, salinity stress presents a multifaceted challenge to plant germination, impacting water uptake, cellular function, and overall seedling establishment.
