abiotic stresses Flashcards
1
Q
What are the main climate and environmental challenges for agriculture?
A
- Increased temperature
- Droughts
- Salinity
- Pollution
- Flooding
- Increased population
- Soil impoverishment
- Soil erosion
- Disease and pests
2
Q
Why is there a need for a new green revolution?
A
- Due to increased human population and reduced crop productivity, a new green revolution is needed.
- This requires developing stress-resilient crops, dependent on a better understanding of plant physiology.
3
Q
What types of environmental stresses affect plants?
A
- Abiotic stresses: temperature, water, salinity, pollution, etc.
Stress can be continuous or chronic, causing 30-50% crop loss. - Responses: Stress-specific or general, localized or systemic, short-term (minutes) to long-term (weeks).
4
Q
What are the two main types of plant stress responses?
A
- Resistance: Adaptation of physiology and metabolism to reduce stress effects.
- Avoidance: Perceiving stress but tolerating it by reducing growth.
5
Q
What are the three types of plants based on stress responses?
A
- Stress-sensitive: Inadequate response to stress.
- Stress-resistant: Adequate responses to mitigate stress effects.
- Stress-tolerant: Constitutively prepared for stress.
6
Q
What is water stress and how does it affect plants?
A
- Caused by critical water deficit leading to reduced growth.
- Physiological effects: Osmotic imbalances, reduced photosynthesis, membrane porosity, etc.
- Morphological responses: Stomatal closure, leaf wax production, root extension.
7
Q
What are some adaptations of plants to water stress?
A
- Metabolism reduction upon water receipt.
- Evasion: Short life cycles, water-dependent leaf production.
- Root adaptations: Long roots for deeper moisture.
8
Q
What are the effects and adaptations of plants to salt stress?
A
- Salt stress leads to osmotic imbalances and cellular toxicity.
- Adaptations: Osmoregulation, bladder cells for salt storage, salt-excreting glands.
9
Q
How do plants respond to temperature extremes (high and low)?
A
- High temperature: Stomatal closure, protective proteins, saturated fatty acids.
- Low temperature: Dormancy induction, compatible solute production, unsaturated fatty acids.
10
Q
What types of pollution stress affect plants and their responses?
A
- Air pollution: Inhibits stomatal movement, reduced photosynthesis.
- Soil pollution: Inhibits photosynthesis and growth, toxic but some species thrive on contaminated land.
- Adaptations: Detoxification enzymes, selective nutrient uptake, phytoremediation, phytomining.
