S11 - Session O5 - Temperature-dose response of tomato fruit set and pollen quality

Authors: Ana Cristina Zepeda *, Leo F.M. Marcelis, Ep Heuvelink

Greenhouse crop production requires high energy inputs, particularly during the cold and dark winter months in temperate climates. It has become increasingly important in recent years to reduce energy consumption in order to cut costs and reduce CO 2 emissions. Temperature integration is an energy-saving strategy that allows temperature to fluctuate within pre-defined bandwidths instead of using rigid set points for heating and ventilation. Previous research showed that young tomato plants are able to integrate temperature up to 10 days. However, in fruiting crops, thermosensitivity of reproductive organs can further constrain the temperature strategy. High or low temperatures contribute considerably to crop losses due to an increased failure of pollen development and fruit set. We studied the effect on pollen viability, pollen germination, fruit set and seed number of tomato flowers exposed to different temperatures (14°C, 30°C and 34°C) and with different durations (4, 6 or 8 days for the 14°C treatment and 1, 3 or 4 days for the 30°C and 34 °C treatment). Pollen viability and germination were considerably reduced at 30°C and 34 °C at all durations compared to constant optimal conditions (18 °C). These flowers led to small seedless fruits. Pollen viability and germination were also reduced at 14 °C but not as much as at high temperatures. Within temperatures, pollen viability and germination was lower at longer durations (3 and 4 days for 30 °C treatments and 8 days for 14 °C treatment) compared to short durations. Including a temperature dose function of fruit set and pollen quality into crop models can help with predicting more realistic scenarios for temperature integration strategies.