CAULIFLOWER AND MELON PRODUCTION UNDER SOILLESS TECHNIQUE USING DIFFERENT WATER QUALITIES

Rapid population growth and increased total water consumption are rapidly depleting the availability of water. Agriculture demands more water than any other activity on the planet; therefore, a good solution for agricultural purposes will be to promote the use of non-conventional water resources, including the saline water. This study focused on the hydroponic production of two crops: cauliflowers as winter crop, and melon as spring one, utilizing three inert substrates: gravel (GR), perlite (PR) and pozzolana (PZ). Fresh water was used for cauliflower irrigation, whereas for melon the irrigation was practiced with saline water (4 dS/m). The experiment was carried out in a glasshouse located in the south-east of Italy. The experimental work was carried out aiming to: i) regulate the root environment; ii) evaluate the plant water consumption and the agronomic growing parameters; iii) characterize the nutrient status of the crops during the growing cycle; iv) evaluate the nutrients status in the drainage water; v) estimate the yield production and evaluate the fruit quality. Regarding the cauliflower crop, the plant and root dry weight was significantly higher on the plants grown on PZ, while no significant differences were found between PR and GR substrates. The yield production was significantly higher on PZ (53 t ha^-1) with respect to PR and GR (38-39 t ha^-1); also the average fruit weight was higher on PZ (1200 g) with respect to the other two substrates (900-980 g). In the melon crop, the plant dry weight was higher on the plants grown on PZ, while the root dry weight was higher on PZ and PR. The total yield was higher on PR and PZ (95-100 t ha^-1) with respect to GR (80 t ha^-1). The shortening of the cropping cycle will results in fertilizer saving, maximizing its efficient use and eliminating the underground water pollution. Vitamin C, ascorbic acid, and nitrate content of fruits varied in the substrates and were lower than the standard one, without any health hazard side effects.