BF15-MAIZE GROWTH AND YIELD INCREASED BY CO-INOCULATION WITH Azospirillum argentinense AND FLUORESCENT Pseudomonas DEPENDS ON BACTERIAL STRAIN COMPATIBILITY

MARCOS VALLE FJ ; MARTÍNEZ RD; DÍAZ PR; PAGNUSSAT LA; CREUS CM; MARONICHE GM

Congreso; SAMIGE 2022; 2022

The benefits that Azospirillum spp. and fluorescent Pseudomonas exert on plants, added to the costof chemical fertilizers and the risk of environmental contamination, have led to their biotechnologicalexploitation as mixed inoculants. However, most of these formulations are usually developed withoutconsidering strain compatibility in the field. The objective of this work was to study the effect ofdifferent strain combinations of Azospirillum and Pseudomonas on the vegetative growth and yield of maize (Zea mays L.) under productive conditions. Seven strain combinations were selected based onprevious results and first characterized for in vitro compatibility in mixed biofilms. A. argentinenseAz39 and Az19 expressing DsRed protein were combined with Pseudomonas strains LSR1, A506, andZME4 in mixed suspensions (1:1 CFU ratio), and spotted on NNi medium to form macrocolony biofilmsfor 72 h at 28 °C. Azospirilla growth was then analyzed by quantifying the red fluorescence ofmacrocolonies. Strain combinations were then used to carry out a field inoculation trial during2021/2022 season in Balcarce (Buenos Aires, Argentina). Maize seeds (Nidera AX 7784 VT3P) wereinoculated with 10 µl per seed (final dose: 107 CFU.seed-1 of each strain) of the combinations A.argentinense Az39 + P. fluorescens A506; A. argentinense Az19 + P. fluorescens A506; A. argentinenseAz39 + P. putida LSR1; A. argentinense Az19 + P. putida LSR1; A. argentinense Az39 + P. rhodesiaeZME4; A. argentinense Az19 + P. rhodesiae ZME4 or saline solution as a control without inoculation.The experiment was carried out on rainfed and no tillage conditions, crop was not fertilized. Theevaluated growth and phenological parameters included aerial dry weight on V6 stage (ADW),harvestable corn ear index (HCE), total aboveground dry matter (TDM), thousand grain weight (TGW)and crop yield. Data was analyzed by ANOVA followed by LSD Fisher test (p