Comparison between conventional and organic floating systems for lettuce and tomato (Lactuca sativa and Lycopersicon esculentum) seedling production

The floating system is a common technique for tobacco and vegetable seedling production. Two production systems (CON conventional and ORG organic) and three substrate mixtures (2:1, 1:1 and 1:2 peat: vermiculite, v/v) were evaluated for lettuce and tomato seedling production at 2004 and 2005, Electrical conductivity, dissolved oxygen and pH values of the nutrient solution in ORG system were significantly lower than the corresponding values for CON system. Moreover, the growth and water content of ORG seedlings were the lowest. The presence of mycorrhiza in the ORG can be plausibly ascribed to the better conditions (higher O-2, lower EC) of this water-solution. Quality of seedlings grown under the ORG system as well as the dry weight were higher than those of the CON system. Furthermore, plant height and fresh weight were higher and the root growth was lower in seedlings grown under CON system. The seedlings grown using 1:1 substrate mixture had the highest root growth. The estimated production cost did not indicate any differences between organic and conventional systems.