A recent study released by Purdue University examines the impact of photosynthetic photon flux density (PPFD) on the growth and development of strawberry runner tips propagated indoors. The findings provide valuable insights for optimizing light conditions to enhance propagation success and improve transplant quality in controlled environments.
The United States grows about 20% of the world's strawberries, with California producing 89% of the nation's crop and Florida 10%. Increasing competition from neighboring countries is driving growers in the United States to use protected structures such as high tunnels, greenhouses, and indoor farms to help extend the growing season and increase yields, particularly in nontemperate climates.
Light intensity plays a crucial role in plant development, influencing photosynthesis, rooting success, and overall plant vigor. Although several studies have focused on evaluating the use of sole-source lighting from light-emitting diode (LED) fixtures during propagation, few have examined the effects of photosynthetic photon flux density (PPFD) on rooting of vegetative plant material such as strawberry runner tips. A common industry practice is to maintain low PPFDs (≤70 µmol·m‒2·s‒1) to minimize excessive water loss until active root growth begins.
This research evaluates how different PPFD levels affect the physiological responses of strawberry runner tips, including rooting efficiency, leaf development, and overall productivity.
The results show that manipulating light intensity strongly influences the establishment and quality of young plants, laying the groundwork for refined propagation practices. Although higher PPFD levels enhanced biomass and rooting of indoor-propagated strawberry runner tips, they also triggered radiation stress, evidenced by increased shoot mortality, reduced chlorophyll, and lower gas exchange. Higher PPFDs may help shorten the rooting period, but additional measures—such as selecting runner tips with larger crowns—are necessary to optimize final plant growth and yield.
By refining indoor propagation strategies, growers can produce more uniform and resilient transplants, ensuring better adaptation to field or greenhouse conditions. These findings support advancements in controlled-environment agriculture, contributing to more efficient and sustainable strawberry production.
Dr. Góemez is Associate Professor of Controlled Environment Agriculture at Purdue University. The research component of her program includes evaluation of new crops and innovative production systems for the controlled environment horticulture industry.
The full story can be found on the ASHS HortScience electronic journal website at the link here.
