Discussion of the distribution and abundance of living organisms and how these properties are affected by interactions between the organisms and their environment
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Salt stress is on the same concept as heat shock. It is when the environment is not optimal, and the body/organism has to react to certain 'stresses/shocks' to keep homeostasis. Certain genes are turned on, with a different set of enzymes and structural proteins being expressed to help the functions proceed normally as possible.
Salinity stress happens because cells are... well, cells. A cellular membrane which is semi-permeable, allowing osmosis to occur (diffusion (movement along a concentration gradient) of water across membranes). Now, let's say a cell is placed in a hypertonic solution (more ions in solution than cell), the cell loses water through the cell membrane (as the concentration of ions in the solution is higher than in the cell), causing the cell to become shriveled. If a cell was placed in a hypotonic solution, the cell will fill with water, and eventually burst. As expected, this causes extreme discomfort in organisms, therefore, to reduce the pain, an organism could undergo ANS and Endocrine (regulating systems (both involuntary) in the body) changes. Such, an organism such as a bivalve would respond by "clamming up", removing contact with the high/low salinities in water.
Likewise, I also have a question. Osmoregularity in crabs is obtained by what methods, other than Sodium Potassium Ion Exchange Pumps and concentrated urine?
Sorrie about that. Yeah, I was talking about plant cells. ANS? Autonomic Nervous System. Y'know, sympathetic, parasympathetic, reactions that occur in your body against a stimulus, i.e. pupils dilating, err.. bladder, yeah, you got it. Wait a sec...
Covered well in Campbell and Reece 8th edition
I agree that it has to do with the environment. When the environment is not optimal, then your body begins to produce more salt than necessary. This creates a state of shock that can affect vital organs. It is not something that you want to happen.
The U.N. Environment Program estimates that approximately 20% of agricultural land and 50% of cropland in the world is salt-stressed. Natural boundaries imposed by soil salinity also limit the caloric and the nutritional potential of agricultural production. These constraints are most acute in areas of the world where food distribution is problematic because of insufficient infrastructure or political instability.
is anybody know when soils in arid regions of the world are irrigated, solutes from the irrigation water can accumulate and eventually reach levels that have an adverse affect on plant growth. Current estimates indicate that 10 - 35% of the world's agricultural land is now affected, with very significant areas becoming unusable each year. It is a world-wide problem, but most acute in North and Central Asia, South America and Australasia. Although careful water management practices can avoid, or even reclaim damaged land, crop varieties that can maintain yields in saline soils also have an important role.
In contrast to crop plants, there are wild plants that thrive in the saline environments along the sea shore, in estuaries and saline deserts. These plants, called halophytes, have distinct physiological and anatomical adaptations to counter the dual hazards of water deficit and ion toxicity.
Salinity can affect any process in the plant's life cycle, so that tolerance will involve a complex interplay of characters. Research projects at Liverpool have investigated details of the physiology and biochemistry of salt tolerance and also looked at methods to screen overall plant performance that could be used in breeding programmes.
One recent project investigated two species of sorghum (Sorghum bicolor and S. sudanense) represented by 21 accessions. Although increasing sodium chloride concentrations significantly reduced all aspects of growth, there was considerable variation between the accessions. Root and shoot length measurements of the accessions, and the progeny of a cross between four of them, indicated that a great proportion of the differences was genetically determined.
9 posts • Page 1 of 1
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