Horticultural Science and Technology ISSN:1226-8763(Print) 2465-8588(Online) 원예과학기술지

This study aims to determine effects of heating greenhouse and root-zone prior to sunrise in winter season on water uptake, photosynthesis, plant growth and yield for tomato rockwool hydroponics. Greenhouse heating was controlled at 25°C prior to sunrise with 4-day intervals [Control: None heating, PH-30: 30min-heating (07:30–08:00), PH-60: 60min-heating (07:00–08:00), PH-90: 90min- heating (06:30–08:00)] with Sap Flow- and Integrated Solar Radiation-automated irrigation systems (SF, ISR) in experiment I. Root-zone heating was controlled at 19°C prior to sunrise (RPH-90) or at 13°C (Control) with ISR system in experiment II. The substrate temperature was increased to 4°C for both PH-30 and PH-60 treatments, and to 7°C for PH-90. In the SF system, the first irrigation started average 18, 26, 30 mins earlier under the PH-30, PH-60, and PH-90, respectively compared to the ISR system. The water uptake was higher as heating duration was longer. The photosynthetic rate under the PH-90 was higher than that in the PH-30. The degree of leaf area change was greater between the PH-30 and Control, followed by between the PH-60 and PH-90. The substrate temperature ranged from 13.3 to 19.1°C under the RPH-90 treatment, whereas it ranged from 11.0 to 17.2°C under the control in the Experiment II. The water use efficiency (WUE), leaf area, specific leaf area, and marketable yield was higher about 7.0, 10.3, 23.8, and 23.0%, respectively under the RPH-90, compared to the control.