Drought Resistance in Plants
Plants have developed morphological, physiological, and biochemical mechanisms to resist drought:
a) Drought Avoidance
- Deep and extensive root systems → access water from deeper soil layers.
- Leaf modifications: small size, waxy cuticle, leaf rolling → reduce water loss.
- Reduced stomatal conductance → conserve water.
b) Drought Tolerance
- Osmotic adjustment: accumulation of solutes to maintain cell turgor.
- Production of protective proteins (LEA proteins) and antioxidants.
- Maintain metabolic activity under low water availability.
c) Drought Escape
- Short life cycle crops → complete growth before onset of severe drought.
- Example: Pearl millet, Rabi pulses (chickpea) in semi-arid regions.
d) Drought Recovery
- Ability to resume growth after stress ends.
- Some crops can re-green leaves or resume flowering after rainfall.
Examples of Drought-Resistant Crops in India
|
Crop Type |
Examples |
|
Cereals |
Pearl millet, Finger millet, Sorghum, Barley |
|
Pulses |
Chickpea, Pigeon pea, Moth bean |
|
Oilseeds |
Groundnut, Safflower, Sunflower |
|
Vegetables |
Okra, Brinjal (drought-tolerant varieties) |
Fact: Dryland agriculture relies heavily on drought-resistant crops and varieties to minimize yield loss.
Key Points for ASRB NET
- Drought reduces growth, photosynthesis, reproduction, and yield.
- Plants resist drought through avoidance, tolerance, escape, and recovery strategies.
- Morphological adaptations: deep roots, leaf rolling, reduced leaf area.
- Physiological adaptations: stomatal closure, osmotic adjustment, antioxidant activity.
- Crop selection in drylands should be based on drought resistance and length of growing season (LGS).
Drought Avoidance and Drought Management in Agriculture
Drought Avoidance
Definition: Drought avoidance refers to plant strategies that help crops escape the adverse effects of water deficit by reducing water loss or accessing soil moisture efficiently.
Key Mechanisms of Drought Avoidance:
|
Mechanism |
Description & Example |
|
Deep Root System |
Roots grow deeper into soil to access residual moisture (e.g., Sorghum, Pearl Millet) |
|
Leaf Morphology Adaptations |
Small leaves, thick cuticle, hairy or waxy leaves reduce transpiration (e.g., Millet, Groundnut) |
|
Stomatal Regulation |
Closure of stomata during peak stress reduces water loss |
|
Leaf Rolling/Leaf Shedding |
Reduces leaf area exposed to sun, conserving water |
|
Early Maturity (Drought Escape) |
Crops complete their life cycle before severe drought sets in (e.g., Chickpea, Pigeon Pea) |
Facts:
- Drought avoidance is more effective in semi-arid and arid regions where moisture stress is frequent.
- Focuses on reducing water loss rather than tolerating it.
Drought Management
Definition: Drought management refers to agronomic, soil, and water conservation practices aimed at minimizing the adverse effects of drought and improving crop productivity under water-limited conditions.
Components of Drought Management:
Agronomic Practices
|
Practice |
Description & Example |
|
Crop Selection |
Drought-tolerant or short-duration crops (millets, pulses) |
|
Sowing Time Adjustment |
Early sowing to utilize monsoon rains effectively |
|
Cropping Pattern |
Mixed/intercropping to reduce risk and maximize water use |
|
Fallowing |
Leaving land unplanted for a season to conserve moisture |
Soil & Water Conservation
|
Practice |
Description |
|
Contour Bunding |
Reduces runoff on slopes, improves infiltration |
|
Terracing |
Prevents soil erosion, retains water |
|
Mulching |
Organic/plastic mulch reduces evaporation |
|
Micro-Catchments / Water Harvesting |
Collect runoff water for supplemental irrigation |
Irrigation & Moisture Management
|
Practice |
Description |
|
Supplemental Irrigation |
Water applied during critical growth stages |
|
Drip / Sprinkler Irrigation |
Efficient use of limited water resources |
|
Moisture Retention Techniques |
Deep plowing, conservation tillage, residue retention |
Policy & Risk Management
- Early warning systems for drought prediction.
- Crop insurance and government support schemes.
- Community-based watershed management programs.
Difference Between Drought Avoidance and Drought Management
|
Feature |
Drought Avoidance |
Drought Management |
|
Definition |
Plant strategy to escape water deficit |
Agronomic and soil-water practices to reduce drought impact |
|
Focus |
Plant morphology, physiology, life cycle |
Crop planning, soil and water conservation, irrigation |
|
Examples |
Deep roots, leaf rolling, early maturity |
Mulching, contour bunding, supplemental irrigation |
|
Level |
Biological / plant-level |
Farm / field / community-level |
|
Goal |
Minimize water stress internally |
Maximize productivity under water-limited conditions |
Facts
- Drylands occupy ~85–98 M ha in India; drought management is crucial for ~55% of India’s rainfed area.
- Drought-avoidant crops like millets, chickpea, pigeon pea form the backbone of dryland agriculture.
- Techniques like mulching and contour bunding can improve soil moisture by 15–25%.
- ICAR-CRIDA (Hyderabad) focuses on drought management and development of drought-resistant varieties.
