Optimizing Strawberry Propagation: New Research Balances Light Intensity for Stronger Plants

The United States contributes approximately 20% to global strawberry production, with California and Florida being the leading domestic producers. Growing competition from other countries is prompting U.S. growers to utilize protected structures, including high tunnels, greenhouses, and indoor farms, to extend growing seasons and increase yields, particularly in non-temperate climates.

The Critical Role of Light Intensity in Plant Development

Light intensity is a crucial factor influencing plant development, photosynthesis, rooting success, and overall plant vigor. While previous studies have examined sole-source LED lighting during propagation, research on the specific effects of photosynthetic photon flux density (PPFD) on the rooting of vegetative plant material, such as strawberry runner tips, has been limited. Industry practice typically involves maintaining low PPFDs (≤70 µmol·m‒2·s‒1) to minimize water loss until active root growth begins.

Purdue University Investigates Optimal PPFD Levels

Research led by Dr. Celina Góemez, Associate Professor of Controlled Environment Agriculture at Purdue University, investigated how different PPFD levels affect the physiological responses of strawberry runner tips. This included evaluating rooting efficiency, leaf development, and overall productivity.

Key Findings: Balancing Growth and Radiation Stress

The results indicate that light intensity significantly impacts the establishment and quality of young strawberry plants.

Although higher PPFD levels enhanced biomass and rooting in indoor-propagated strawberry runner tips, they also induced radiation stress.

This stress was evidenced by increased shoot mortality, reduced chlorophyll levels, and lower gas exchange rates. The study suggests that while higher PPFDs may shorten the rooting period, additional strategies, such as selecting runner tips with larger crowns, are necessary to optimize final plant growth and yield.

Advancing Sustainable Strawberry Production

These findings support the refinement of indoor propagation strategies, enabling growers to produce more uniform and resilient transplants. This contributes to improved adaptation to field or greenhouse conditions and advances controlled-environment agriculture, fostering more efficient and sustainable strawberry production.