The effect of different day/night temperature regimes on growth,development and yield of glasshouse tomatoes

Summary

The response of glasshouse grown tomatoes, cv. Counter, to day/night temperature regimes was examined in two consecutive years. In both years three day/night temperature regimes, with the same average 24-hour temperature, were applied in duplicate, i.e. high/low, equal, and low/high. Differences in temperature were maintained from three days after planting (4 December 1984 and 3 February 1986) until 13 May 1985 and 1 May 1986, respectively. Plant development (increase in number of trusses) was not affected.by the temperature regime. Growth in length of the stem was strongly reduced by a lower day temperature. In the first experiment the crop at the low day temperature treatment was damaged by leaf scorch, most likely caused by low transpiration. Consequently, early yield was lower for this treatment. In the second experiment no leaf scorch occurred and no significant differences in early yield were found. Final yield and average fruit weight, until 1 July for both experiments, were higher at the higher night temperature. Shelf life of the fruits and internal quality was not influenced by the temperature regime. Thus, the length of a tomato plant can be manipulated by the difference between day and night temperature, while development and early yield depend greatly on the average 24-hour temperature. Final yield can be higher at higher night temperature and the same average temperature because the crop is more robust. Temperature control based on average 24-hour temperat-ure can be used to minimize energy. consumption and, together with other growth factors, to optimize financial yield.