EFFECT OF PROLONGED DAY TEMPERATURE IN NIGHT-TIME AND DIFFERENT LEVELS OF NIGHT TEMPERATURE ON GROWTH OF CORDYLINE "LORD ROBERTSON".

G. Serra, C. Carrai
The energy problem has caused to relook at many aspects of the use of energy in protected cultivation in order to reduce its incidence on final production costs. The so-called split-night temperature regime has been the first positive answer to this kind of approach.

The aim of this research was to verify the efficiency of prolonged day temperature during the first part of the night.

This research on Cordyline "Lord Robertson" was laid out in a block of 8 microgreenhouses where the temperatures were controlled by individual systems of refrigerators and electrical resistances. A low-velocity speed ventilation system provided good uniformity of air temperature. Relative humidity was integrated, when needed, to 70–80% and a double sheet of plastic net maintained the light intensity under 20 Klux.

The treatments were applied in a split-plot design with three levels of night temperature (16, 19, 22°C), each splitted into two sub-treatments with the day temperature (24°C) maintained during the light hours or prolonged in the night for a number of hours equal to 40% of natural daylength. Statistical analysis showed significant mean effects of treatments on observed growth parameters, but the interaction effects were slight and more complicated to be explained. Dry matter in each plant organ (roots, stem, leaves) was always higher in the prolonged day temperature treatments; the maximum increase of leaf dry matter (111%) was observed at the lowest night temperature regime (16°C). This thermal regime resulted the most effective in increasing dry matter production in all plant organs, leaf length and width and stem height.

In conclusion prolonged day temperature regime allowed a good growth rate in spite of the low temperature at the end of the night, resulting in energy saving.

Serra, G. and Carrai, C. (1988). EFFECT OF PROLONGED DAY TEMPERATURE IN NIGHT-TIME AND DIFFERENT LEVELS OF NIGHT TEMPERATURE ON GROWTH OF CORDYLINE "LORD ROBERTSON".. Acta Hortic. 229, 393-398
DOI: 10.17660/ActaHortic.1988.229.44
https://doi.org/10.17660/ActaHortic.1988.229.44

Acta Horticulturae