Efficiency of inoculant with Azospirillum brasilense on the growth and yield of second-harvest maize1

ABSTRACTThe misuse of fertilizers has become a growing concern in terms of agricultural and environmental sustainability. One alternative to reduce the impact of chemical fertilizers is the use of inoculants containing nitrogen-fixing and plant growth promoting bacteria. This study aimed at evaluating the effects of an inoculant with Azospirillum brasilense on the growth and yield of secondharvest maize. The experimental design was randomized blocks with three replications, in a 3 × 5 factorial scheme. The treatments consisted of three inoculation methods (control without inoculation, seed inoculation and leaf-sprayed inoculation at the V4 stage) and five cover N-fertilization doses (0 %, 25 %, 50 %, 75 % and 100 %, with the 100 % dose corresponding to 50 kg ha-1 of N as urea). Inoculated plants showed a greater growth for height (9.5 % and 16 %), stem dry biomass (49 % and 6.75 %) and root dry biomass (123 % and 97 %), respectively for seed inoculation and spraying, as well as increases in ear size (8 %), chlorophyll content (4 %), 1,000-grain weight (12 %) and grain yield (29 %), when compared to non-inoculated plants. The effects of N doses were only significant for 1,000-grain weight and grain yield (kg ha-1), with seed inoculation providing a higher yield for second-harvest maize