4. salinity stress
DESCRIPTION
4. Salinity stress. Two kinds of problems due to high soil salinity 1. Osmotic stress 2. Specific ion effects of high [Na +] , [Cl - ], [SO 4 -2 ] inactivate enzymes, inhibit protein synth. Plant Strategies 1. Osmotic adjustment to allow water uptake use inorganic ions, organic solutes - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: 4. Salinity stress](https://reader035.vdocuments.net/reader035/viewer/2022081416/5681306d550346895d964cc2/html5/thumbnails/1.jpg)
![Page 2: 4. Salinity stress](https://reader035.vdocuments.net/reader035/viewer/2022081416/5681306d550346895d964cc2/html5/thumbnails/2.jpg)
![Page 3: 4. Salinity stress](https://reader035.vdocuments.net/reader035/viewer/2022081416/5681306d550346895d964cc2/html5/thumbnails/3.jpg)
4. Salinity stress
Two kinds of problems due to high soil salinity1. Osmotic stress
2. Specific ion effects of high [Na+], [Cl-], [SO4-2]
inactivate enzymes, inhibit protein synth.
Plant Strategies1. Osmotic adjustment to allow water uptake
use inorganic ions, organic solutes
2. Salt exclusion or compartmentation todeal with ion effects.
•prevent entry at roots •prevent transport to shoot•keep away from sensitive organelles
vacuolar compartmentation• extrude salt into glands
![Page 4: 4. Salinity stress](https://reader035.vdocuments.net/reader035/viewer/2022081416/5681306d550346895d964cc2/html5/thumbnails/4.jpg)
![Page 5: 4. Salinity stress](https://reader035.vdocuments.net/reader035/viewer/2022081416/5681306d550346895d964cc2/html5/thumbnails/5.jpg)
Facultative CAM switch to CAM during salt stress
![Page 6: 4. Salinity stress](https://reader035.vdocuments.net/reader035/viewer/2022081416/5681306d550346895d964cc2/html5/thumbnails/6.jpg)
5. O2 deficiency
Typically only a problem in flooded soilsor heavily compacted soils.
O2 diffusion to roots is inhibited.
Flooding sensitivity and tolerance vary greatlyand are related to anatomical and biochemicaldifferences.
![Page 7: 4. Salinity stress](https://reader035.vdocuments.net/reader035/viewer/2022081416/5681306d550346895d964cc2/html5/thumbnails/7.jpg)
![Page 8: 4. Salinity stress](https://reader035.vdocuments.net/reader035/viewer/2022081416/5681306d550346895d964cc2/html5/thumbnails/8.jpg)
Hypoxia and root functiongrowth inhibitionactive transport reduced
Flooding sensitive plants
Flooding tolerant plants
Soil conditions associated with anoxiatoxic forms of some ions, e.g. Fe+2
H2S from SO4-2
![Page 9: 4. Salinity stress](https://reader035.vdocuments.net/reader035/viewer/2022081416/5681306d550346895d964cc2/html5/thumbnails/9.jpg)
Corn roots develop large gas spaces when oxygen deficient. Fig. 25.18
![Page 10: 4. Salinity stress](https://reader035.vdocuments.net/reader035/viewer/2022081416/5681306d550346895d964cc2/html5/thumbnails/10.jpg)
6. Air pollution
What are the major air pollutants?
What are their effects on plants?
What determines variation in sensitivity?
![Page 11: 4. Salinity stress](https://reader035.vdocuments.net/reader035/viewer/2022081416/5681306d550346895d964cc2/html5/thumbnails/11.jpg)
![Page 12: 4. Salinity stress](https://reader035.vdocuments.net/reader035/viewer/2022081416/5681306d550346895d964cc2/html5/thumbnails/12.jpg)
![Page 13: 4. Salinity stress](https://reader035.vdocuments.net/reader035/viewer/2022081416/5681306d550346895d964cc2/html5/thumbnails/13.jpg)
Ozone enters leaves through stomata during normal gas exchange. As a strong oxidant, ozone (or secondary products resulting from oxidation by ozone such as reactive oxygen species) causes several types of symptoms including chlorosis and necrosis. It is almost impossible to tell whether foliar chlorosis or necrosis in the field is caused by ozone or normal senescence. Several additional symptom types are commonly associated with ozone exposure, however. These include flecks (tiny light-tan irregular spots less than 1 mm diameter), stipples (small darkly pigmented areas approximately 2-4 mm diameter), bronzing, and reddening. Ozone symptoms usually occur between the veins on the upper leaf surface of older and middle-aged leaves, but may also involve both leaf surfaces (bifacial) for some species. The type and severity of injury is dependent on several factors including duration and concentration of ozone exposure, weather conditions, and plant genetics. One or all of these symptoms can occur on some species under some conditions, and specific symptoms on one species can differ from symptoms on another. With continuing daily ozone exposure, classical symptoms (stippling, flecking, bronzing, and reddening) are gradually obscured by chlorosis and necrosis.
![Page 14: 4. Salinity stress](https://reader035.vdocuments.net/reader035/viewer/2022081416/5681306d550346895d964cc2/html5/thumbnails/14.jpg)
Heagle, A.S. 1989. Ozone and crop yield. Annual Review of Phytopathology 27:397-423.
EPA estimates an agricultural crop loss of $2 billion to $3 billion dollars per year attributable to ozone exposure; the extent of forest damage is currently being studied.
![Page 15: 4. Salinity stress](https://reader035.vdocuments.net/reader035/viewer/2022081416/5681306d550346895d964cc2/html5/thumbnails/15.jpg)
![Page 16: 4. Salinity stress](https://reader035.vdocuments.net/reader035/viewer/2022081416/5681306d550346895d964cc2/html5/thumbnails/16.jpg)
![Page 17: 4. Salinity stress](https://reader035.vdocuments.net/reader035/viewer/2022081416/5681306d550346895d964cc2/html5/thumbnails/17.jpg)
![Page 18: 4. Salinity stress](https://reader035.vdocuments.net/reader035/viewer/2022081416/5681306d550346895d964cc2/html5/thumbnails/18.jpg)
![Page 19: 4. Salinity stress](https://reader035.vdocuments.net/reader035/viewer/2022081416/5681306d550346895d964cc2/html5/thumbnails/19.jpg)
![Page 20: 4. Salinity stress](https://reader035.vdocuments.net/reader035/viewer/2022081416/5681306d550346895d964cc2/html5/thumbnails/20.jpg)
![Page 21: 4. Salinity stress](https://reader035.vdocuments.net/reader035/viewer/2022081416/5681306d550346895d964cc2/html5/thumbnails/21.jpg)
w = S= p =
w = S= p =
w =
w =
Xylem Phloem
1. W = S + P
2. W of xylem and phloem < 03. S < 0 if there are any solutes!4. P of phloem > 0! “pressure flow”5. Water moves passively from higher to lower w
![Page 22: 4. Salinity stress](https://reader035.vdocuments.net/reader035/viewer/2022081416/5681306d550346895d964cc2/html5/thumbnails/22.jpg)
Xylem Phloem
1. W = S + P
2. W of xylem and phloem < 03. S < 0 if there are any solutes!4. P of phloem > 0! “pressure flow”5. Water moves passively from higher to lower w
p = 1.0
p = 0.8
S= -2.8
S= -1.8
w = -1.8
w = -1.0
w = - 1.2
w = -1.6