R ESPONSE OF FLOUR CORN ( Zea mays L. var. Amylacea) ) TO THE INOCULATION OF Azospirillum AND Pseudomonas

Plant growth-promoting bacteria (PGPB) that inhabit root rhizosphere of plants are of great agricultural importance due to their ability to produce phytohormones during root colonization. These phytohormones produce physiological changes in the plant that favor a greater absorption of nutrients, promote growth and increase production. This study analyzed the effect of inoculation of two of these bacteria, Azospirillum sp. and Pseudomonas fluorescens, , under field conditions representative of the Andean Highlands. The experiment was carried out using flour corn seed of the INIAP-101 variety in a randomized complete block design with six repetitions. The treatments corresponded to: T1 (Azospirillum sp.), T2 (P. P. fluorescens), ), T3 (Azospirillum sp. and P. fluorescens), ), T4 (control, conventional chemical fertilization) and T5 (absolute control). The application of these bacteria significantly increased (p<0.05) the root length, the diameter of the cob, and the yield of fresh corn ("elotes" or "choclos"). The combined inoculation of these bacteria (T3) obtained the highest yield, with 19.70 t ha(-1) of fresh corn; while the chemical control and the absolute control got 17.12 and 13.58 t ha(-1) of fresh corn, respectively. The economic analysis of T3 reported a benefit/cost of 1.35, which indicates that the synergism of these two bacteria could be a sustainable strategy to improve yields and reduce the use of chemical fertilizers for corn production in the Andean region.