| Title: | "Plant Factories Are Heating Up: Hunting for the Best Combination of Light Intensity, Air Temperature and Root-Zone Temperature in Lettuce Production" |
| Author(s): | Carotti L; Graamans L; Puksic F; Butturini M; Meinen E; Heuvelink E; Stanghellini C; |
| Address: | "Department of Biological, Geological and Environmental Sciences, Alma Mater Studiorum, University of Bologna, Bologna, Italy. Greenhouse Horticulture, Wageningen University and Research, Wageningen, Netherlands. Horticulture and Product Physiology, Wageningen University and Research, Wageningen, Netherlands" |
| ISSN/ISBN: | 1664-462X (Print) 1664-462X (Electronic) 1664-462X (Linking) |
| Abstract: | "This study analyzed interactions among photon flux density (PPFD), air temperature, root-zone temperature for growth of lettuce with non-limiting water, nutrient, and CO(2) concentration. We measured growth parameters in 48 combinations of a PPFD of 200, 400, and 750 mumol m(-2) s(-1) (16 h daylength), with air and root-zone temperatures of 20, 24, 28, and 32 degrees C. Lettuce (Lactuca sativa cv. Batavia Othilie) was grown for four cycles (29 days after transplanting). Eight combinations with low root-zone (20 and 24 degrees C), high air temperature (28 and 32 degrees C) and high PPFD (400 and 750 mumol m(-2) s(-1)) resulted in an excessive incidence of tip-burn and were not included in further analysis. Dry mass increased with increasing photon flux to a PPFD of 750 mumol m(-2) s(-1). The photon conversion efficiency (both dry and fresh weight) decreased with increasing photon flux: 29, 27, and 21 g FW shoot and 1.01, 0.87, and 0.76 g DW shoot per mol incident light at 200, 400, and 750 mumol m(-2) s(-1), respectively, averaged over all temperature combinations, following a concurrent decrease in specific leaf area (SLA). The highest efficiency was achieved at 200 mumol m(-2) s(-1), 24 degrees C air temperature and 28 degrees C root-zone temperature: 44 g FW and 1.23 g DW per mol incident light. The effect of air temperature on fresh yield was linked to all leaf expansion processes. SLA, shoot mass allocation and water content of leaves showed the same trend for air temperature with a maximum around 24 degrees C. The effect of root temperature was less prominent with an optimum around 28 degrees C in nearly all conditions. With this combination of temperatures, market size (fresh weight shoot = 250 g) was achieved in 26, 20, and 18 days, at 200, 400, and 750 mumol m(-2) s(-1), respectively, with a corresponding shoot dry matter content of 2.6, 3.8, and 4.2%. In conclusion, three factors determine the 'optimal' PPFD: capital and operational costs of light intensity vs the value of reducing cropping time, and the market value of higher dry matter contents" |
| Keywords: | climate management dry matter allocation efficiency leaf expansion light use efficiency production climate resource use efficiency vertical farm; |
| Notes: | "PubMed-not-MEDLINECarotti, Laura Graamans, Luuk Puksic, Federico Butturini, Michele Meinen, Esther Heuvelink, Ep Stanghellini, Cecilia eng Switzerland 2021/02/16 Front Plant Sci. 2021 Jan 28; 11:592171. doi: 10.3389/fpls.2020.592171. eCollection 2020" |
