THE EFFECT OF BIOSTIMULANT APPLICATION ON LETTUCE GROWTH PARAMETERS
Biostimulant application is an innovative and ecofriendly agronomic practice with increasing interest in horticultural production. In the present manuscript, five biostimulant products (e.g. seaweed extracts+macronutrients; humic and fulvic acids; Si+Ca+Zn; Si; amino acids) were tested on two pot-grown lettuce cultivars (Romaine type: cv. Doris; Batavia type: cv. Manchester) aiming to evaluate the effects on plant growth parameters (plant height; SPAD index; total plant weight number of leaves; fresh and dry weight of leaves; leaf area; specific leaf area). A varied effect of biostimulant treatment was observed on SPAD index and plant height in the case of Romaine lettuce, while the combination of Si+Ca+Zn and Si increased SPAD index and plant height in Batavia lettuce, respectively. Regarding plant growth parameters of Romaine lettuce, seaweed extract had a beneficial effect on total plant weight, weight of leaves and leaf area, while humic and fulvic acids increased the number of leaves, Si+Ca+Zn increased dry matter content of leaves and Si resulted to the highest specific leaf area. In the case of Batavia, the application of Si+Ca+Zn had the most beneficial effect on the tested growth parameters, except for the case of dry matter content of leaves which was the highest when plants were treated with seaweed extracts. Our results indicate positive effects of biostimulants on lettuce plant growth.However, a varied response was observed depending on the biostimulant product, especially in the case of Romaine lettuce. On the other the combination of Si+Ca+Zn improved most of the growth parameters in Batavia type.