This episode is part of our “What Plants Crave” series, where Dr. Sabeh speaks with growers, researchers, engineers, and manufacturers who work in controlled environment agriculture, to get their insights about the direction of the industry, and of course, what exactly it is that plants crave.

This week’s episode features John Ertle. John Ertle is a Plant Physiologist at PP Systems, specializing in the development and application of portable photosynthesis measurement instruments for studying leaf-level gas exchange. In his role, he not only conducts plant science research within the company but also collaborates with academic and industry partners to enhance research outcomes.

​John discusses his work on lettuce tipburn—a common calcium deficiency issue in vertical farming that affects crop quality. He shares insights into strategies for mitigating tipburn and enhancing lettuce health. Additionally, Ertle talks about his development of thermal time models to assess the chilling tolerance of grafted watermelon seedlings, facilitating their safe transport to open-field growers. With a Ph.D. in Horticulture and Crop Science from The Ohio State University, Ertle emphasizes the importance of precise environmental control and physiological monitoring in advancing controlled environment agriculture. ​