Indoor agriculture systems can allow for precise manipulation of the mean daily temperature (MDT), carbon dioxide (CO2) concentration, and photosynthetic photon flux densities (PPFD). Identifying how these environmental parameters interact to influence crop growth, development, yield, and color can assist growers with selecting their desired growing environment. Therefore, the objectives of Expt. 1 and 2 were to quantify and model how PPFD and CO2 concentrations interact with MDT to influence the growth, yield, and quality of hydroponically grown green butterhead 'Rex' and red oakleaf lettuce 'Rouxai RZ'. In Expt. 3 we developed models to predict growth parameters and cardinal temperatures of lettuce, arugula, and kale from 8 to 33 ℗ʻC. In Expt. 1, lettuce 'Rex' and 'Rouxai RZ' were grown in deep-flow hydroponic tanks under a PPFD of 150 or 300 Îơmol℗ʺm⁰́₂2℗ʺs⁰́₂1 for 17 h℗ʺd-1 at MDTs of 20, 23, or 26 ℗ʻC. PPFD and MDT interacted to influence biomass accumulation of both cultivars. In Expt. 2, lettuce 'Rex' and 'Rouxai RZ' were grown under a PPFD of 300 Îơmol℗ʺm⁰́₂2℗ʺs⁰́₂1 and at the same MDTs as Expt. 1, but with CO2 concentrations of 500, 800, or 1200 Îơmol℗ʺmol-1. Dry mass of both cultivars was influenced by the interaction of CO2 and MDT; biomass accumulation was greatest at 800 Îơmol℗ʺmol-1 CO2 at MDTs of 23 and 26 ℗ʻC. In Expt. 3, 'Rex' and 'Rouxai RZ', kale 'Red Russian', and arugula 'Astro' were grown at MDTs of 8, 13, 18, 23, 28, or 33 ℗ʻC. 'Rex' and 'Rouxai RZ' had similar base and optimal temperature estimates of 8 ℗ʻC and 26 ℗ʻC, while arugula and kale were lower at 6 ℗ʻC and 23 ℗ʻC.
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