Drought-Induced Responses in Maize under Different Vapor Pressure Deficit Conditions

Area of Science:

• Plant physiology and molecular biology
• Agricultural science
• Environmental stress response

Background:

• Plant water stress is influenced by soil water availability and atmospheric evaporative demand.
• Understanding plant responses to combined drought and vapor pressure deficit (VPD) is crucial for crop resilience.

Purpose of the Study:

• To investigate the physiological, biochemical, and molecular responses of maize to varying soil water content (SWC) and VPD levels.
• To determine the impact of combined water stress and evaporative demand on maize growth and gene expression.

Main Methods:

• Maize was subjected to three SWC levels (well-watered, 45%, 35%) and three VPD levels (low, medium, high).
• Measurements included plant growth parameters (leaf weight, area, number), gas exchange (photosynthesis, stomatal conductance, water use efficiency), C4 enzyme activity, and transcription factor expression.
• Statistical analysis (p < 0.01) was used to assess treatment effects.

Main Results:

• Severe drought (35% SWC) combined with high VPD significantly reduced leaf weight, area, and number.
• Leaf area reduction ranged from 30-60% under drought conditions across different VPD levels compared to well-watered plants.
• Photosynthesis, stomatal conductance, and water use efficiency were significantly reduced, especially at 35% SWC and high VPD.
• C4 enzyme levels and ABA-related transcription factors were upregulated under increased stress.

Conclusions:

• Combined high VPD and severe drought significantly impede maize plant development.
• These stresses induce significant physiological and molecular changes, including alterations in C4 enzymes and ABA signaling pathways.
• The findings highlight the critical role of VPD in exacerbating drought stress effects on maize.