INCIDENCE OF LETTUCE TIPBURN AS RELATED TO HYDROPONIC SYSTEM AND CULTIVAR

Abstract

The incidence of tipburn was studied by growing late winter and spring lettuce cultivars in two consecutive experiments, in hydroponics, either with Deep Flow Technique (DFT) or on solid growth substrates, in Messinia, NW, Greece. Both experiments showed that the fresh marketable yield of lettuce in DFT was approximately twice as great compared to that of plants grown on solid substrates. Tipburn injury was not observed in the late winter experiment whereas it was severe in the spring one. In particular, lettuce grown with DFT in the spring presented significantly greater level of injury whereas when grown on perlite the least. Their shoot calcium concentration was significantly lowest whereas when grown on perlite the highest. Between the two spring cultivars included, ‘Merlin’, which presented the greatest injury, also had significantly higher shoot fresh weight, lower root/shoot ratio, higher tissue water content, and lower nitrogen, potassium, calcium, and magnesium concentrations compared to ‘Gramsi’.