Influence of sub-optimal temperature on tomato growth and yield : a review

The effects of temperature on growth, development and yield of tomato (Lycopersicon esculentum) are reviewed with special emphasis on cultivar differences. The focus is on sub-optimal temperatures, above the level where chilling injury occurs. Temperature has a large effect on all aspects of development. Leaf and truss initiation rates decrease linearly with decreasing temperature. Although these rates may be different for different cultivars their response to temperature is the same. Young plants grown at sub-optimal temperatures produce thicker leaves, so they intercept less light and therefore have a lower relative growth rate. There was no interaction between temperature and cultivar for relative growth rate and related traits. In a crop producing fruits, this aspect is less important as most of the light is intercepted anyway. At sub-optimal temperatures, fruit set is reduced as a result of poorer pollen quality. The period between anthesis and ripening of the fruit increases and, as the growth rate of the fruit at a certain developmental stage is independent of temperature, fruits become larger at sub-optimal temperature. Higher temperature leads to an increase in early yield, at the cost of vegetative growth, but may also cause a delay in later trusses. Total yield over a whole season might be equal at lower temperatures, but higher tomato prices early in the season do not make it economically profitable to reduce the temperature in the greenhouse. Short-term effects might thus be different from long-term effects. In the literature, the link between yield and whole plant growth is often missing, limiting the possibilities of studying the underlying processes that contribute to changes in yield. Breeding for cultivars with equal production at lower temperatures is hampered by the limited variation for temperature response in cultivated tomato. Therefore breeders have to look for other sources of variation, as in related wild Lycopersicon species.