Yield and Quality of Vegetables Grown in a Floating System for Ready-to-Eat Produce

Floating system is gaining interest in horticulture mainly for ready-to-eat products. However, there is still little information on crops response to several technical variables. For instance, ideal plant density is not known for all species as well as their tolerance to nutrient solution salinity. The experiment was carried out on radish (Raphanus sativus) and lamb's lettuce (Valerianella locusta), species with different edible parts of plant. For both species, three sowing densities (370, 640 and 980 plants m(-2) for radish and 1200, 1800 and 2400 plants m(-2) for lamb's lettuce) and three nutrient solutions similar for composition but different in salinity by addition of 0, 10 and 20 mmol L-1 of NaCl were compared. Radish yields were higher at the lower densities and at the minor salinity. Lamb's lettuce production increased along with density but external quality decreased because of longer leaves. Salinity reduced yield but also resulted in shorter leaves which improved external quality of production at higher densities. Differences occurred also in internal quality: increasing salinity reduced nitrates in dry matter of both species and also increased total phenolic compounds and antioxidant activity in lamb's lettuce. In the latter species, high densities negatively affected quality as resulted in greater nitrate content.