CO2 and Water Utilization Efficiencies of a Closed Transplant Production System as Affected by Leaf Area Index of Tomato Seedling Populations and the Number of Air Exchanges

Abstract

The closed transplant production system is defined as a transplant production system covered with opaque and insulated walls, where the energy and mass transfer between inside and outside the system is controlled and/or restricted, and using artificial lights. CO2 utilization efficiency of a closed transplant production system, CUE, was defined as the ratio of the amount of CO2 fixed by plants to that supplied into the system. Water utilization efficiency of the system, WUE, was defined in the same way as CUE. Tomato seeds were sown on plug trays and grown for 20 days in the system. CUE and WUE increased with increasing leaf area index (LAI) and decreasing the number of air exchanges. Maximum CUE (0.93) and WUE (0.95) during the present study were obtained at maximal LAI of 1.2 and minimal number of air exchanges of 0.02 h-1. Results suggest that a high LAI and a low number of air exchanges provide high CUE and WUE values.