Effect of ground heat exchanger for root-zone cooling on the growth and yield of aeroponically-grown strawberry plant under tropical greenhouse condition

With the increasing cost of fossil fuel to generate power for cooling purposes, there is a need for alternative methods of cooling system that is sustainable and economically viable in producing high quality crops under tropical condition. This study aimed to investigate the effect of ground heat exchanger (GHE) for root-zone cooling on the growth, yield, and economic returns of aeroponically-grown strawberry plants under tropical greenhouse condition. The experiment had two treatments; the root-zone cooling methods (GHE, Air-conditioning Unit (ACU), and Control – no root-zone cooling) and photoperiods (8-hours, 16-hours, and 12-hours). We observed that the root-zone mean temperature under GHE was maintained at 26.75 °C, which was 2.61°C higher than ACU and 2.17°C lower than the control. The GHE and ACU did not significantly differ in terms of plant's growth with larger and number of leaves, and longer petioles than the control. We found no significant interaction of the treatments on the yield nor difference between GHE and ACU with 181-186 g/plant. Projected benefit cost ratio using GHE is 4.24 and annual return of investment is at 32%. This study underscores the feasibility of GHE application for root-zone cooling under tropical greenhouse condition.