Yield, nutrition, and leaf gas exchange of lettuce plants in a hydroponic system in response to inoculation.

Inoculation with is a promising approach to increase plant yield and nutrient acquisition. In this context, this study aimed to estimate the concentration that increases yield, gas exchange, and nutrition of lettuce plants in a hydroponic system. The research was carried out in a greenhouse in Ilha Solteira, Brazil. A randomized block design with five replications was adopted. The treatments consisted of concentrations in nutrient solution [0 mL "non-inoculated", 7.8 × 10, 15.6 × 10, 31.2 × 10, and 62.4 × 10 colony forming units (CFU) mL of nutrient solution]. There was an increase of 20% and 19% in number of leaves and 22% and 25% in shoot fresh mass with concentrations of 15.6 × 10 and 31.2 × 10 CFU mL as compared to the non-inoculated plants, respectively. Also, concentration at 31.2 × 10 CFU mL increased net photosynthesis rate by 95%, intercellular CO concentration by 30%, and water use efficiency by 67% as compared to the non-inoculated treatments. The concentration of 7.8 × 10 CFU mL improved shoot accumulation of Ca, Mg, and S by 109%, 74%, and 69%, when compared with non-inoculated plants, respectively. Inoculation with at 15.6 × 10 CFU mL provided the highest fresh leaves yield while inoculation at 15.6 × 10 and 31.2 × 10 CFU mL increased shoot fresh mass and number of leaves. Concentrations of 7.8 × 10 and 15.6 × 10 increased shoot K accumulation. The concentrations of 7.8 × 10, 15.6 × 10, and 31.2 × 10 CFU mL increased shoot N accumulation in hydroponic lettuce plants.