The effect of biostimulant applications on yield and quality in hydroponic lettuce growing

This research aims to examine the effects of biostimulant use on plant growth and yield in hydroponically grown lettuce. The study was conducted at the Mediterranean University Faculty of Agriculture, within the Horticulture Research and Application area, and the cultivation was carried out in static water culture tanks. The plant material used in the study was the 'Caipira' lettuce variety of the species Lactuca sativa. The biostimulants utilized included BM-Root-Pan, which contains bacteria, and Maxsoil, a commercial product containing humic and fulvic acids. The treatments were designed as Control (K), Control + Maxsoil (K+M), Control + Rootpan (K+R), and Control + Maxsoil + Rootpan (K+M+R), and the research was conducted with three replications. In the study, measurements were taken for leaf length and width, dry matter content in the leaves, plant root length, soluble solid dry matter (TSS) in the leaves, average yield per plant, yield per unit area, plant leaf EC and pH values, number of leaves, root weight, head diameter, head height, root collar diameter, colour and chlorophyll content (SPAD). According to the research results, the effects of the treatments on leaf width, chlorophyll (SPAD) value, dry matter content in the leaves, head diameter, yield per plant (g/plant), and yield per unit area (g/m²) were found to be statistically significant, while no differences were detected in other measurements and analyses. The highest leaf width (16.59 cm) was observed in the K+M treatment, the highest SPAD value (27.09) in the K+R+M treatment, and the highest dry matter content, excluding the control, was found in the K+M (5.84), K+R (5.86), and K+R+M (5.60) treatments. The highest head diameter (29.96 cm) was recorded in the K+M treatment. In terms of average yield per plant, the lowest value (96.31 g) was obtained from the K+R+M treatment, while the other treatments did not differ significantly among themselves (119.3-123.82 g). The effects of the treatments on yield per unit area were significant, with the highest yield (7080.8 g/m²) from the K+M treatment and the lowest yield (5326.9 g/m²) from the K+R+M treatment, while the control yielded 6767.1 g/m². This study demonstrated the positive effects of humic and fulvic acid-containing preparations in static water culture. KEYWORDS: Biostimulant, Curly Lettuce, Fulvic Acid, Humic Acid, Water Culture