Interactive effects of air and nutrient solution temperature and CO2 concentration on growth, yield, and quality of fresh-cut culinary herbs

• Air average daily temperature (ADT) is the primary driver of biomass accumulation. • A nutrient solution temperature (NST) of 32 °C was detrimental to plant growth. • 900 μmol∙mol ‒1 CO 2 only benefited biomass accumulation of parsley. • Cilantro had the greatest biomass at a lower ADT (20 °C) and medium NST (28 °C). Basil ( Ocimum basilicum ), cilantro ( Coriandrum sativum ), parsley ( Petroselinum crispum ), and sage ( Salvia officinalis ) are among the most popular fresh-cut herbs; however, there is limited information available on how to maximize their growth and development in controlled environments. Given that cut herbs are sold by weight, the goal is to maximize harvestable fresh mass while minimizing production time, space, and energy inputs. Our objective was to determine the most effective nutrient solution temperature (NST), carbon dioxide (CO 2 ) concentration, and air average daily temperature (ADT) to maximize yield. NST, CO 2 , and ADT setpoints of 24, 28, or 32 °C, 450 or 900 μmol∙mol ‒1 , and 20 or 23 °C respectively, were utilized. ADT contributed the most to the accumulation of shoot fresh mass (SFM) in basil, sage, and parsley. Increasing ADT from 20 to 23 °C increased SFM of parsley, sage, and basil by 46, 100, and 180%, respectively. Increasing CO 2 from 450 to 900 μmol∙mol ‒1 increased SFM of parsley and cilantro by 13 and 14% but decreased basil SFM by 12%. Increasing the NST from 24 to 28 °C increased the SFM of cilantro by 9%, and the SFM of sage was greatest when the NST was 24 or 28 °C. We conclude that SFM can be maximized by maintaining a 23 °C ADT, 28 °C NST, and 450 μmol∙mol ‒1 CO 2 for basil and sage, a 23 °C ADT, 24 °C NST, and 900 µmol·mol –1 CO 2 for parsley, and a 20 °C ADT, 28 °C NST, and 450 µmol·mol –1 CO 2 for cilantro.