植物逆境生理

• Photosynthesis
– Decrease in Pn – Decrease in stomatal aperture – Decrease in Fv/Fm – Decrease in quantum yield
• Respiration
– Change in respiration path
Plant Environmental Stress Physiology
Fan Hai
What is Plant Stress
• Plant stress is the adverse reaction of plants to environmental conditions that are unfavorable to growth, such as lack of sufficient nutrients, inadequate watering, flooding, high or low temp., disease or insect infestation.
• Strain can be elastic or plastic depending on the degree and lasting time of stress.
– Elastic strain: recoverable, temporary – Plastic strain: non-recoverable, permanent
• Oxidative stress induced by reactive oxygen species (ROS)
– Reactive oxygen species are highly reactive molecules containing atom oxygen. It mainly include 4 species: O2.-, ·OH, H2O2 and 1O2
Stress
Biotic stress
Abiotic stress
pathogen microbes
insects
allelopathy
drought
water flooding
High temp.
Temp.Baidu NhomakorabeaLow temp.：chilling , freezing
photoinhibition
light
UV damage
chemicals
Salinity Alkalinity Insecticide, herbicide Air pollution
Plant stresses greatly diminish crop yields
Biotic and abiotic stresses can reduce average productivity by 65%~87%
– Under chilling and drought stress, the respiration rate increase first and then decrease
• Changes of phytohormone level
– Decrease in IAA, CTK, GB – Significant increase in ABA – Increase of Eth under flooding
• E.g. Turn EMP-TCA pathway to PPP under drough, pathogen and wounding stress.
– Decrease in respiration rate under freezing, hot and flooding stress
– Increase in respiration rate under wounding and pathogen stress
I. Damages of stress to the plant
stress
Primary damage
Primary directdamage
（injury to the plasma lemma）
Primary indirect damage
（dysfunction of metabolism）
– ROS can attack chloroplast, mitochondria and other organelles.
– ROS can also attack membrane by causing membrane peroxidation.
Barley
11400
Potato
94100
Sugar beet 121000
4600 1880 1610 2830 1720 2050 28300 42600
Biotic
1952 726 666 1051 924 765 17775 17100
Abiotic
12700 11900 5120 16200 7960 8590 50900 61300
Secondary damage
（e.g. water stress in salt stress）
I. Damages of stress to the plant
• Bio-membrane
– Change in membrane phase – Change in membrane constituents – Change in membrane permeability
Abiotic losses (% of record yield)
65.8 82.1 69.3 80.6 75.1 75.4 54.1 50.7
What is Strain
• Strain is the biologic changes of plants under the influence of plant stress.
Table: Average yields and record yields of 8 major crops
Crop
Record Average Average losses
yield
yield
Corn
19300
Wheat
14500
Soybean 7390
Sorghum 20100
Oat
10600