Plant Drought Stress: Effects, Mechanisms and Management

Environmental Constraints to Plant Productivity

• Drought is the most severe environmental constraint to plant productivity, exceeding losses from all other causes in reducing crop yield.

Effects of Drought Stress on Plants

• Drought stress primarily affects plant growth and physiology.
• Drought stress disturbs the plant's water relations, carbon metabolism, and nutrient uptake.
• The effects of drought stress on plant growth and physiology have been reviewed by the International Rice Research Institute (IRRI) and the University of California, Riverside.

Physiological Responses to Drought Stress

• Drought stress reduces CO2 assimilation by leaves, mainly due to stomatal closure and reduced photosynthetic activity.
• Potassium helps in osmotic adjustment to withstand drought stress by facilitating the uptake of water and minerals.
• Low-molecular-weight osmolytes (e.g., proline, glycine betaine) play a role in protecting plants against drought stress by maintaining cellular turgor and stabilizing membranes.

Plant Hormones and Drought Stress

• Abscisic acid (ABA) modulates the plant responses towards drought, triggering stomatal closure, reducing water loss, and inducing gene expression for drought tolerance.

Drought Stress and Plant Growth

• Major deterrents to growth in plants under drought stress include reduced water availability, impaired nutrient uptake, and increased oxidative stress.
• Mechanisms that help plants withstand drought stress include drought avoidance, drought tolerance, and drought recovery.

Molecular Mechanisms of Drought Tolerance

• Drought-responsive genes have been identified, including those involved in ABA signaling, osmoregulation, and antioxidant defenses.

Managing Plant Drought Tolerance

• Plant drought tolerance can be managed through breeding for drought-tolerant crops, improving irrigation systems, and implementing conservation agriculture practices.