Water availability affects the relationship between pollen intensity and seed production

Area of Science:

• Plant reproductive biology
• Ecology
• Environmental science

Background:

• Seed production is influenced by water availability, pollen amount (intensity), and pollen quality.
• The relationship between pollen receipt and seed set follows a saturating dose-response curve.
• Water availability and pollen intensity can interact, affecting seed production and potentially pollinator effectiveness.

Purpose of the Study:

• To investigate how water availability affects plant fitness indicators (seed set, fruit set, seed mass) in *Phacelia parryi*.
• To determine the impact of water availability on the relationship between pollen intensity and seed production.
• To understand the implications for pollinator effectiveness and selection.

Main Methods:

• A greenhouse experiment manipulated water availability (high vs. low) in *Phacelia parryi* plants.
• Plants were hand-pollinated across a range of pollen intensities, measuring pollen deposited, seed production, and seed mass.
• Piecewise regression analyzed the relationship between pollen intensity and seed production, alongside water effects on fitness measures.

Main Results:

• Average seed production per fruit was 21% higher in high-watered plants compared to low-watered plants.
• The relationship between pollen intensity and seed production varied significantly between water treatments.
• High-water plants showed a broader range where increased pollen deposition led to greater seed production.

Conclusions:

• Water availability alters the efficiency of converting received pollen into seeds produced.
• The effect of water on pollen-to-seed conversion is dependent on the pollen intensity environment.
• These findings highlight the complex interplay between water, pollen, and plant reproductive success.