Initiation and Development of Flower Trusses Affected by Acclimatizing Temperature in Grafted Tomato Plugs

Abstract

Tomato plugs were grafted at preinitiating (PI) and developing (DV) stages of the first truss and were acclimatized at 20/20, 25/25, 30/30 and 30/15°C (day/night) for 10 days, followed by planting into ground beds. In PI-grafted plants, the number of leaves (NL) under the first truss and between the first and the second trusses increased at higher temperatures (25/25 and 30/30°C), but decreased at low night temperature (30/15°C) . The number of flowers (NFL) on the first and the second trusses decreased at higher temperatures, but increased at low night temperature. Low temperature accelerated anthesis of the first truss (ANT1) but delayed ANT2, while low night temperature accelerated ANT1 without delaying ANT2. The temperature effects on NL, NFL and the timing of anthesis were not observed in DV-grafted plants. In PI-grafted plants, the number and yield of normal, marketable, fruit on the first and second trusses decreased with increasing temperature but increased at low night temperature. These results suggest that acclimatization at low night temperature (30/15°C) prevents the increase in NL under the first truss and increases the early yield of normal fruit on the tomato plants grafted at the plug stage.