EFFECTS OF THE EVAPORATIVE COOLING SYSTEM IN GREENHOUSES USED FOR ROSES AND CARNATIONS

We report the results of the cultivation of roses and carnations at Pisa during 1970/71 in three greenhouses,each with an area of about 200 m² and about 21 metres long.
Two greenhouses were air-conditioned with a cooling system, one in glass (A), and one in plastic (B); the third one in plastic was not air-conditioned (C).

Roses of cv. "Super Star" grafted into R. canina and R.indica major, and carnations of cv."Super Cardinal" were cultivated.

The carnations were transplanted on 16 February 1970 at a spacing of 21,4 plants per m². The roses were transplanted during 4–5 February at a spacing of 7,8 plants per m².

We studied the climatic modification produced by cooling, the effects on the crops, the cost of the installation and maintenance of the cooling system.

In the case of carnations we observed the performance of plants in relation to the production of cut-flowers (quantity and quality) and of cuttings in mother plants.

In the greenhouses with cooling systems we observed a reduction in the maximum temperature of 3–4° C in position 1, (3,5 m away from the fans), and of 5–7° C in position 2 (3,5 m away from the humidified pads), compared with the temperatures in the greenhouse without cooling.
The reduction of the temperature in the greenhouse with cooling compared to the outside temperature was 1–2° C in position 1 and 3–4° C in position 2.

We also noted an increase in the minimum relative humidity of 10–20% compared to the one outside.

The most important results were:

1. Increase in production of cuttings by carnation mother-plants of 5–10 cuttings per plant in greenhouse A and 2–5 in greenhouse B (during 5 months cultivation).

2. No difference in the final production of carnation for cut-flowers.
   On the other hand an earlier production of cut-flowers and an increased percentage of split-flowers was observed.

3. With regard to rose cultivation an increase of six flowers per plant in greenhouse A, and of four flowers in greenhouse B (durins the 15 months of cultivation) was noted.

4. The total costs of installation of the cooling system were Lira 800 per square metre per year.
   Such expense was compensated by the increase in production of roses and carnation

Symposium on Cultivation of Flowers under Protection in the Mediterranean Regions

R. Tesi

https://doi.org/10.17660/ActaHortic.1974.43.11