Sources and Doses of Nitrogen Associated with Inoculation with Azospirillum brasilense Modulate Growth and Gas Exchange of Corn in the Brazilian Amazon

Abstract

The specific objective of the study was to evaluate effect of inoculation with Azospirillum brasilense and nitrogen (N) doses on vegetative growth and gas exchange in Zea mays L. The experimental design adopted was the completely randomized, in a 4 2 2 factorial scheme, in the following way: four doses of N (0 60 120 and 180 kg ha-1 of N), two sources of N (common urea and urease inhibitor-treated urea) and absence and presence of inoculation with A. brasilense, with four replications. The evaluations were made for vegetative growth of the plant (plant height, stem diameter, leaf area, number of leaves, dry mass of stem, root, leaves and aerial part and total dry mass) and photosynthesis, stomatal conductance, transpiration, internal carbon, relationship between internal and external carbon and content of chloroplast pigments. The application of N provided an improvement in plant growth, and, in general, the dose of 180 kg ha-1 N associated with A. brasilense, promoted an increase in stem diameter, photosynthesis, stomatal conductance, transpiration and internal carbon ratio of the corn. The treatment with urease inhibitor, greatly promoted the stem diameter, transpiration, Ci/Ca ratio and chlorophyll (Chl) a, b, total compared to urea treatment. The inoculation of the corn seeds with the bacteria and the use of N fertilization, regardless of the source, promoted an improvement in the vegetative growth of the hybrid, improving the vegetative growth and the physiological responses of corn when applied to the highest dose of 180 kg/ha N. © 2021 Friends Science Publishers