Vertical farming for lettuce production in limited space: a case study in Northern Thailand

Suwimon Wicharuck; Nuttapon Khongdee; Ar Man; Wahyu Nurkholis Hadi Syahputra; Parichat Yalangkan; Prapaporn Chaiphak; Chatchawan Chaichana

doi:10.7717/peerj.17085

Vertical farming for lettuce production in limited space: a case study in Northern Thailand

PeerJ. 2024 Apr 10:12:e17085. doi: 10.7717/peerj.17085. eCollection 2024.

Authors

Suwimon Wicharuck^{1

2}, Nuttapon Khongdee³, Ar Man⁴, Wahyu Nurkholis Hadi Syahputra⁵, Parichat Yalangkan², Prapaporn Chaiphak², Chatchawan Chaichana²

Affiliations

¹ Office of Research Administration, Chiang Mai University, Chiang Mai, Thailand.
² Energy Technology for Environment Research Center, Department of Mechanical Engineering, Faculty of Engineering, Chiang Mai University, Chiang Mai, Thailand.
³ Department of Highland Agriculture and Natural Resources, Faculty of Agriculture, Chiang Mai University, Chiang Mai, Thailand.
⁴ Graduate Master's Degree Program in Energy Engineering, Department of Mechanical Engineering, Faculty of Engineering, Chiang Mai University, Chiang Mai, Thailand.
⁵ Agricultural Engineering Program, Department of Mechanical Engineering, Faculty of Engineering, Chiang Mai University, Chiang Mai, Thailand.

Abstract

Background: Greenhouse vertical farming under natural sunlight is an alternative farming technique that grows crops in a stacking column and extends in a vertical direction. Sunlight availability is one of the crucial factors for crop development in vertical farming. Therefore, this investigation aimed to examine the effect of sunlight availability on lettuce growth and yields at different levels of vertical shelves.

Methods: Six shelves were constructed with three levels: upper, middle and lower levels. Lettuces (Lactuca sativa L.) as 'Baby Cos' and 'Green Oak' at 14 days after sowing were planted on the three levels. The photosynthetic photon flux density (PPFD) was recorded, and the PPFD values were then converted to the daily light integral (DLI). Plant height and canopy width were measured three times at 14, 21 and 28 days after transplanting. At maturity, fresh weight (FW) was directly monitored after harvest.

Results: The results showed that the highest PPFD and DLI values were found at the upper level (PPFD 697 μmol m^-2 s^-1 and DLI 29 mol m^-2 d^-1) in comparison to the middle (PPFD 391 μmol m^-2 s^-1 and DLI 16 mol m^-2 d^-1) and lower (PPFD 322 μmol m^-2 s^-1 and DLI 13 mol m^-2 d^-1) levels. The lowest plant height and canopy width values were observed on the upper levels for both lettuce varieties during the three measurement dates. The middle ('Baby Cos' = 123.8 g plant^-1 and 'Green Oak' = 190.7 g plant^-1) and lower ('Baby Cos' = 92.9 g plant^-1 and 'Green Oak' = 203.7 g plant^-1) levels had the higher values of FW in comparison to the upper level ('Baby Cos' = 84.5 g plant^-1 and 'Green Oak' = 97.3 g plant^-1). The values of light use efficiency (LUE) showed an increased trend from the upper to lower levels in both varieties, with values of 'Baby Cos' of 0.10 g mol^-1 in the upper level, 0.28 g mol^-1 in the middle level and 0.26 g mol^-1 in the lower level and 'Green Oak' of 0.12 g mol^-1 in the upper level, 0.44 g mol^-1 in the middle level and 0.57 g mol^-1 in the lower level. The findings of the study indicated the viability of utilizing vertical shelves for lettuce production.

Keywords: Lettuce production; Sunlight availability; Vertical farming.

MeSH terms

Agriculture*
Crops, Agricultural
Farms
Humans
Infant
Lactuca*
Thailand

Grants and funding

This research project was supported by Fundamental Fund 2024, Chiang Mai University. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.