Abstract
The growing interest in the use of inoculants with diazotrophic bacteria that promote plant growth, providing increase in crop productivity, occurs because of the high costs of chemical fertilizers and the concern about environmental quality. Given the above, this study aimed to evaluate, in field conditions, the effect of nitrogen fertilization and inoculation with Azospirillum brasilense and Herbaspirillum seropedicae on the productivity, phytotechnical parameters and nutritional state of corn. The experiment was set in a randomized block design, with nine treatments and six replicates: Control without N and without inoculation; A. brasilense inoculation without N; H. seropedicae inoculation without N; 30 kg ha-1 of N at the sowing; A. brasilense + 30 kg ha-1 of N at the sowing; H. seropedicae + 30 kg ha-1 of N at the sowing; 30 kg ha-1 of N at the sowing + 90 kg ha-1 of N in covering; A. brasilense + 30 kg ha-1 of N at the sowing + 90 kg ha-1 of N in covering; and H. seropedicae + 30 kg ha-1 of N at the sowing + 90 kg ha-1 of N in covering. The evaluated parameters were: plant height, stem diameter, ear insertion height, ear weight, ear length, number of grain rows per ear, number of grains per ear, ear base diameter, weight of 1,000 grains, shoot dry weight, yield, chlorophyll content, leaf nutrient content and grain nutrient content. The nitrogen fertilization associated with inoculation of A. brasilense and H. seropedicae positively influenced ear weight, ear diameter, number of grains per ear, shoot dry weight, yield and chlorophyll content of corn plants. The contents of N, P, K and Zn in corn leaves increased with nitrogen fertilization and inoculation with A. brasilense and H. seropedicae. The inoculation with A. brasilense without nitrogen fertilization promoted higher accumulations of N, K, Ca and Mg in grains compared with the treatments inoculated with A. brasilense and H. seropedicae and fertilized with 30 and 120 kg ha-1 of N. The inoculation with A. brasilense or H. seropedicae associated with nitrogen fertilization may lead to a reduction in the use of synthetic nitrogen fertilizers in corn cultivation. Key words: Zea mays L., nitrogen, diazotrophic bacteria.
Highlights
Among mineral nutrients, nitrogen (N) is one of the most important and limiting for corn productivity, and its application is required in large amounts in order to meet crop demand (Dotto et al, 2010)
This study aimed to evaluate, in field conditions, the effect of nitrogen fertilization and inoculation with Azospirillum brasilense and H
The ear diameter and the number of grains per ear were higher in the treatment fertilized with 120 kg ha-1 of N, statistically differing (p≤0.05) from the control, the treatment inoculated with H. seropedicae and that inoculated with A. brasilense + 30 kg ha-1 of N (Table 1)
Summary
Nitrogen (N) is one of the most important and limiting for corn productivity, and its application is required in large amounts in order to meet crop demand (Dotto et al, 2010). Environmental costs related to N fertilization have stimulated the search for alternatives that might reduce the use of these fertilizers, without any decrease in production. One way to make it a possible low-cost production without harming the environment is the use of soil biological resources, like diazotrophic bacteria, which are considered as growth-promoting bacteria, for their capacity to fix nitrogen (N2) for the plant and produce growth hormones, such as auxins and gibberellins (Dobbelaere et al, 2002; Radvan et al., 2002)
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