Reducing Tipburn in Lettuce Grown in an Indoor Vertical Farm: Comparing the Impact of Vertically Distributed Airflow vs. Horizontally Distributed Airflow in the Growth of Lactuca sativa
Author
Kaufmann, Christopher JohnIssue Date
2023Advisor
Kacira, Murat
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The University of Arizona.Rights
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction, presentation (such as public display or performance) of protected items is prohibited except with permission of the author.Abstract
Advances in vertical farming and other controlled environment agriculture (CEA) practices have given growers more control in creating the optimal conditions for crop production within a smaller footprint while increasing yields. However, certain hydroponically grown leafy greens grown in plant factories are often at risk of developing tipburn, which is a common morphological disorder that manifests as wilted or shriveled tips of younger leaves. While tipburn is a result of calcium deficiency, it is amplified by poor transpiration conditions in a growth environment, as leaf boundary layer thickness increases from suboptimal airflow at canopy height. Previous research has indicated that airflow supplied to the canopy within thevelocity range of 0.3 - 1.0 m s-1 significantly decreases the thickness of the leaf boundary layer, thus promoting transpiration and reducing tipburn. There are many reasons contributing to the lack of research published investigating optimal methods of airflow distribution in a commercial vertical farm, one of which being the lack of standardization among production facilities. This study compared the performance of two different airflow distribution configurations in the mitigation of tipburn in lettuce within a hydroponic plant production system in a vertical farm at the UA-CEAC. Two cultivars of lettuce were grown (cv. Rouxai and cv. Klee) under two different daily light integral (DLI) values of 13 and 15 mol m-2 d-1 and were subjected to constant airflow by either a vertical or horizontal airflow system. The vertical airflow system directed air downward onto the crop, and the horizontal system distributed air across the plants near the crop canopy. This study investigated the effect of previously modelled airflow systems in the reduction of tipburn in a vertical farm. Comparing vertical airflow and horizontal airflow, both yielded positive results as a means of supplementing airflow to the crop canopy level and thereby mitigating tipburn in both cultivars. Tipburn was observed in 84% of Klee under VAF conditions, 95% under HAF, and 100% in the control at a DLI of 15 mols m-2 d-1, with severities of 38%, 47%, and 58% respectively at a DLI of 15 mols m-2 d-1. In Rouxai, tipburn was documented in 29% of VAF plants, 75% HAF, and 100% of the Control with severities of 3%, 34%, and 63% respectively at a DLI of 15 mols m-2 d-1. Under a DLI of 13 mols m-2 d-1, tipburn Klee comprised 83% of the VAF, 93% HAF, and 100% of the Control plants with severities of 28%, 36%, and 58% respectively. At this lower DLI, 13% of VAF, 65% HAF, and 100% of the Control Rouxai plants were tipburned with severities of 2%, 25%, and 61% respectively.Type
Electronic Thesistext
Degree Name
M.S.Degree Level
mastersDegree Program
Graduate CollegeBiosystems Engineering