Effects of day and night air temperature in early season on growth, productivity and energy use of spring tomato

Abstract

Effects of air temperature on tomato (Lycopersicon esculentum Mill) growth, yield and heating energy consumption were investigated in spring of 1993 and 1994. Tomato plants were grown under nine day/night air temperature regimes formed by factorial combination of three day (19, 20 and 21°C) and three night (16, 17 and 18°C) heating temperature set points. Early (until 30 April) fruit yield increased but early fruit size decreased with increasing daily average air temperature (MT, 24-h mean). The plants grown under high daily average air temperature early in the season had lower fruit yield late in the season. Plants grown under high night air temperature (NT) and low day air temperature (DT) during the early production period achieved high fruit yield in early season and avoided the negative effects of high MT on early fruit size; these plants also had high yield and large fruit size late in the season. The different day and night heating temperature regimes studied caused no more than 10% in heating energy use variation. Therefore, for greenhouse tomato production under Great Lakes conditions (approx. 42°N), the optimal day/night air temperature (from January to April) is 20.8–21.0/18.5–19.0°C (actual air temperatures). Key words: Lycopersicon esculentum, tomato, yield, quality, fruit size, daily average air temperature (MT), day-night air temperature difference (DIF), day air temperature (DT), night air temperature (NT)