Growing radish (Raphanus sativus var. radicula) in plug trays in a floating system

This paper compares the growth of radish 'Tinto F1' grown in a greenhouse in polystyrene plug trays with 84 and 40 cells, on a floating system, with the plants placed on a growing table. Plug trays placed on a floating system were filled with a mixture of perlite and granulated rockwool 1:1, while those placed on a growing table were filled with a peat substrate. Four nutrient solutions were tested in 2 growing cycles in Ljubljana ' the central part of Slovenia. The first cycle took place from 6^th April to 21^st May 2010, and the second from 27^th May to 13^th July 2010. Two nutrient solutions were made from reagents and two from water soluble fertilizer (WSF). Two different N concentrations were also tested. Each experiment consisted of three repetitions and the radishes were harvested three times (at weekly intervals) when plants had formed at least a 2 cm large hypocotyl. In both experiments, the trays with 40 cells (264 plants m^-2) resulted in a higher % of marketable hypocotyls but the number of marketable hypocotyls was not statistically higher in trays with 84 cells (554 plants m^-2). In the second cycle, in which the last harvest was done on 13^th July, the radishes grown on a floating system was more than 60% marketable, but the radishes grown in peat in a tray with 84 cells began to flower and less than 15% of the plants formed a fleshy tap root. The addition of N to the nutrient solution accelerated bolting. The radishes grown in the second cycle on a floating system were harvested 7-14 days earlier than the radishes in a peat substrate.