Plants And Salt Flashcards
What are angiosperms connection with salinity levels, give an example.
Angiosperms are extremely sensitive to salt levels in the soil and do not need high levels of it. An example is the chickpea plant which when they receive a small amount of excess salt they will die.
What is the problem with drawing water from seawater ?
Due to having a high concentration of salts the solute potential is very low and therefore the water potential is very negative in the sea. Therefore plants struggle to move it into their cells.
How does salt water effect enzyme functions ?
The presence of sodium in the water interferes with potassium functions acts as a counter ion. This causes a large decrease in the enzyme activity
What’s the difference between glycophytes and halophytes ?
Halophytes are much more salt tolerant.
Why are HKT1 channels ?
HKT1 channels are found in halophytes. They transport Na into the cytosol and subsequently into the vacuole to stop Na from negatively effecting enzymes in the cytoplasm.
How do halophytes use HKT1 channels ?
Sodium is pumped though channels in to the cytosol and subsequently into the vacuole. Cytosol and vacuole now have low potential (~1.5MPa).
How do halophytes cope with low water potentials in the cytoplasm and vacuole ?
They produce compatible solutes that do not tamper with the enzymes in the cytosol. This produces a low solute potential and therefore draws in water from the soil into the cell.
How do some halophytes get rid of excess salt ?
Some halophytes use bladder cells which intake NaCl from inside normal plant cells. They expand and then explode over the leaf surface. The salt then crystallises on the leaf and rolls off.
Why do desert soils have such low water potentials ?
This is due to the fact that the sand has a charge that strongly attracts water and holds it tight. This is called a low matric potential.
Why are desert plants spherical ?
This shape has the smallest area to volume ratio meaning that water loss is minimal.
How are cacti’s stomata specialised to reduce water loss ?
He stomata in cacti are sunken in crypts. The air in these crypts is very humid meaning there is a small difference in the water potentials of the cells and the air. Therefore water losses is minimised.
What is salt stress ?
Salt stress is one of the most limiting factors of plant growth. Caused by the adverse effects of high concentrations of Na and Cl ions.
What are saline soils ?
Saline soils are soils that have primarly soluble NaCl and NaSO4. Contain sufficient salts to be detrimental to plant growth.
What are sodic soils ?
Capable is alkaline hydrolysis. Mainly Na2CO3.
Whats the difference between primary and secondary salinity ?
Primary salinity is build of of salts over time from the weathering of parent materials or the deposition from oceanic salt.
