Sun Exposure Affects Growth and Harvest Yield of Ocimum basilicum 'Cardinal' L. Grown on an Inexpensive, Vertical Structure

Cardinal Basil (Ocimum basilicum ‘Cardinal’) was grown on a novel, inexpensive, A-frame vertical structure built at Auburn University. The structures were built out of treated lumber with cattle fencing on each of the 2 panel faces. One cattle fencing panel holds 15, 15.2cm by 15.2cm, square pots with one Basil plant per pot. In this study, one A-frame structure with the two panels facing opposite directions vertically occupied 1.5m²  of horizontal ground area, which is the same square footage the a traditional, horizontal greenhouse bench treatment. The objective of this research was to compare how sun exposure, based on structure orientation, affects the growth and fresh leaf harvest yields of Cardinal Basil grown on the A-frame vertical structure compared to the traditional greenhouse bench. There were 4 blocks and 5 treatments per block: a south, north, west, and east facing panels and a horizontal bench (control). There were 15 plants per treatment, per block for a total of 300 plants in the study. Each pot received drip irrigation. Basil plants were harvested to three remaining nodes per plant every 4 weeks, to mimic harvests by a restaurant chef or homeowner utilizing the structure. On each harvest leaf number, fresh and dry leaf weights, and fresh and dry stem weights were recorded. Data results showed one south facing panel (0.75m² horizontally) on the A-frame structure produced similar amounts of leaf fresh weight compared to the traditional greenhouse bench (1.5m²). However, when looking at the A-frame structure as a whole (2 panels per structure; north and south or east and west) plants on each structure produced approximately 1.5 times more leaf fresh weight than those on the greenhouse bench. When comparing 2 south facing panels, they produced about 2 times the leaf fresh weight compared to the greenhouse bench covering the same horizontal production area.