Effect of Photosynthetic Bacteria Concentration on Growth Yield and Physical Quality of Lettuce

Abstract

The purposes of this research were: (1) to develop a process for using Photosynthetic Bacteria (PSB) to enhance the growth of green oak lettuce; (2) to study the effects of different PSB concentrations on the biomass of green oak lettuce; and (3) to investigate their impact on the pH of the growing medium. The experimental sample consisted of green oak lettuce grown under a completely randomized design (CRD) with six treatments (including a control group) and three replicates per treatment. PSB concentrations of 10, 20, 30, and 40 cc per 10 L of water were compared with chemical fertilizer (15-15-15) and a control treatment (plain water). Data were analyzed using analysis of variance (ANOVA) and Duncan’s Multiple Range Test. The results revealed that: (1) Photosynthetic Bacteria (PSB) promoted the growth of green oak lettuce as effectively as chemical fertilizer; (2) at the end of the fifth week, the chemical fertilizer treatment produced the highest mean fresh weight (59.84 g), which was not significantly different from that obtained with the PSB treatment at a concentration of 20 cc per 10 L (58.33 g); and (3) regarding the pH of the growing medium, the application of PSB treatment at concentrations ranging from 10-30 cc per 10 L maintained pH levels between 6.80 and 7.00, which is optimal for nutrient absorption. In contrast, chemical fertilizer significantly reduced the pH to 6.37 (p < 0.05). In conclusion, a PSB concentration of 20 cc per 10 L was the most suitable alternative for reducing chemical fertilizer use, as it maintained the pH balance of the growing medium while providing biomass yields comparable to those achieved with chemical fertilizer.