Inoculation and co-inoculation of lettuce and arugula hydroponically influence nitrogen metabolism, plant growth, nutrient acquisition and photosynthesis

Carlos Eduardo Da Silva Oliveira ^1* Thaissa Julyanne Soares Sena Oliveira ² Arshad Jalal ³ Guilherme Carlos Fernandes ² Andréa Bastos ² Marcelo Rinaldi da Silva ² Gabriela Rodrigues Sant'Ana ¹ Jailson Vieira Aguilar ⁴ Liliane Santos De Camargos ⁴ Tiago Zoz ¹ Marcelo Carvalho Minhoto Teixeira Filho ^2*

• ¹ Agronomy, State University of Mato Grosso do Sul, Dourados, Brazil
• ² Department of Plant Health, Rural Engineering and Soils, Faculty of Engineering, São Paulo State University, Ilha Solteira, Brazil
• ³ King Abdullah University of Science and Technology, Thuwal, Makkah, Saudi Arabia
• ⁴ Faculty of Engineering, São Paulo State University, Ilha Solteira, Brazil

The objective of this study was to investigate the effects of single and combined inoculations of A. brasilense, B. subtilis and P. fluorescens on lettuce and arugula grown in a hydroponic system. The study was carried out in a greenhouse and was designed in randomized blocks with five replications. The treatments consisted of inoculation with A. brasilense, B. subtilis and P. fluorescens and coinoculation with A. brasilense + B. subtilis, A. brasilense + P. fluorescens, B. subtilis + P. fluorescens and A. brasilense + B. subtilis + P. fluorescens via nutrient solution. An increase in the length and fresh mass of the shoot and leaf chlorophyll concentrations of arugula and lettuce was observed under co-inoculations of A. brasilense + P. fluorescens and B. subtilis + P. fluorescens. Greater length, fresh mass and volume of the lettuce root system were observed under the co-inoculations of A. brasilense + B. subtilis, A. brasilense + P. fluorescens and B. subtilis + P. fluorescens in arugula under the inoculations of A. brasilense and A. brasilense + P. fluorescens. Greater nitrate reductase activity was detected in leaves, and lower nitrate accumulation was detected in lettuce and arugula under inoculations with A. brasilense, P. fluorescens and B. subtilis + P. fluorescens. The greatest accumulation of N, P, K, Ca and Mg in the lettuce shoot was obtained under inoculation with P. fluorescens, A. brasilense + P. fluorescens and B. subtilis + P. fluorescens. Co-inoculation with A. brasilense + P. fluorescens and B. subtilis + P. fluorescens was the most efficient combination for increasing the growth, nutrient acquisition and functioning of nitrogen metabolism in arugula lettuce plants.