Stigma development and receptivity in almond (Prunus dulcis)

Area of Science:

• Plant reproductive biology
• Horticultural science
• Agricultural research

Background:

• Almond production relies heavily on effective fertilization and pollination.
• Pollination limitations can significantly impact almond crop yields.
• Understanding stigma receptivity is key to improving pollination efficiency.

Purpose of the Study:

• To investigate almond stigma receptivity across defined developmental stages.
• To clarify the relationship between stigma morphology, pollen germination, tube growth, and fruit set.
• To inform strategies for enhancing almond pollination and crop yield.

Main Methods:

• Utilized light and scanning electron microscopy to analyze stigma development.
• Assessed pollen germination and tube growth following hand pollination at various flower stages.
• Conducted field pollinations to determine the effect of flower age on fruit set.

Main Results:

• Older flowers (flat petal to petal fall stages) showed higher stigma receptivity.
• Increased stigma receptivity correlated with elongated papillae and more exudate in advanced stages.
• Field pollinations confirmed sustained stigma receptivity and nut set in older flowers.

Conclusions:

• Almond stigma receptivity is optimal post-fully open flower stage.
• Stigma remains receptive and supports fruit set even during petal abscission.
• Flower developmental stage is critical for timing bee placement and maximizing pollination success.