NEW TECHNIQUES FOR THE CULTIVATION AND DEFENCE OF TOMATO CROPS IN COLD GREENHOUSE IN THE AREA OF RAGUSA (SICILY)

The authors report the positive results of "Italdor" F1 tomato variety in a greenhouse soil-less culture. This consisted of expanded clay, particle diameter 2–4 mm, contained in 20 l white polyethylene bags. The bags, each carriyng two plants, were fed with a costant N P K nutrient solution (1 – 0.5 – 1.5), enriched with macro and micro elements. A drop irrigation system was used for the distribution of water or nutrient solution. Low cost, easily manageable equipment was used to mix the nutrient solution.

A layout of 2.5 plants/m² was used for the autumn-winter- spring cycle. The bags were arranged in double line on soil covered with a white polyethylene sheet in a cold, plastic greenhouses without any supplementary heating system.

This technique has proved to be a good alternative growing method to the more traditional coltivation in soil.

A second greenhouse of "Italdor", transplanted in soil and cultivated with traditional methods, was kept as a control.

In order to control external pests, a bio-net (14 x 10 type) was applied over all openings in both greenhouses and gave satisfactory results in mechanically excluding aphids, whiteflies and other phytophages, so that the need for periodical insecticide treatments was eliminated or reduced.

In the test greenhouse the temperature in the bags and in the confined environment was satisfactory, as was the relative humidity.

The hybrid was transplanted in mid-November. Crop production was excellent and better in terms of quality and quantity than that obtained on natural soil with traditional coltivation methods. In particular, the "Italdor" hybrid on expanded clay and pollinated by Bombus terrestris (L.) gave very good results. Harvesting started in mid-February on expanded clay and one month later for the control.

On expanded clay, an average of 38.0 marketable fruits per plant were obtained from the first 6 clusters and an average of 30.5 in the control. The mean production was estimated at about 16 kg/m², while the crops cultivated on soil did not reach an average of 10 kg/m² of marketable produce.

We believe that the acceptable cost (L. It. 900 m²), the ready avaiability of both substrate and equipment, the possibility to defence the crop without use of insecticides, and the high unit yield render soil-less culture economically convenient.