Características morfoagrônomicas, produção de grãos e valor nutricional das silagens de milho na forma de ração total submetidos à fertirrigação com silício e inoculação com Azospirillum Brasilense na entressafra agrícola

Abstract

The objective was to assess the morphoagronomic characteristics, grain production, and nutritional value of corn silage and total feed subjected to fertigation with silicon and inoculation with A. brasilense during the agricultural offseason. The experiment was conducted in a randomized complete block design in a 4x2 factorial scheme, with five replications, totaling 40 experimental units. Silicon application corresponded to doses of 0, 4, 8, and 12 kg/ha, without and with inoculation of A. brasilense Ab-V5 and Ab-V6 in a 50% ratio each. The cultivar employed was the maize hybrid (Zea mays L. AG - 1051). Morphological and structural characteristics, biomass production and quantification, grain harvest index health, agronomic efficiency, and the C:N ratio of maize were evaluated during the agricultural offseason. Silages were assessed for microbiology, fermentative profile, and chemical-bromatological composition. An interaction was observed (P<0.05) for variables such as ear length with and without husk, ear diameter with husk (cm), grain production (g/kg), nitrogen deposition, and C/N ratio (g/kg). Regression model estimates showed greater ear length with and without husk at the level of 7.83 and 9.33 kg ha-1 of Si, reaching a maximum point of 33.0 and 20.7 cm, respectively. The ear diameter with husk, which exhibited a linear effect (P<0.05) without the inoculation of A. brasilense, resulted in means ranging from 46.22 to 58.33 mm. Grain production at the level of 7.98 kg/ha reached a maximum production point of 12.35 t/ha. Nitrogen deposition (g/kg) without A. brasilense showed a minimum of 9.61 and a maximum deposition of 12.10 g/kg; in contrast, the C/N ratio decreased from 431.32 to 351.37 g/kg as Si doses increased. There was an isolated effect of Si (P<0.05) for variables such as the number of live and dead leaves, plant height to the tip of the inflorescence (cm), plant height to the flag leaf (cm), green matter production (t/ha), green matter production of leaves, stem (t/ha), water accumulation (t/ha), water use efficiency (kg/DM/mm/ha), dry matter production (t/ha), whole plant weight, and husked ear weight (g); dry matter production of leaves, stem, and ear (t/ha). These variables increased linearly with increasing doses. There was a quadratic effect of Si (P<0.05) for variables such as plant height to ear insertion (cm), ear green matter (t/ha), and husked ear weight (g). Plant height to ear insertion reached a maximum height of 98.54 at a Si dose equivalent to 7.49 kg/ha. The green matter production of the ear benefited up to maximum doses equivalent to 9.33 kg ha-1 of Si, with a production of 17.03 t/ha. The maximum point for husked ear weight was 359.1 g, at a Si dose equivalent to 10.48 kg/ha. There was an effect (P<0.05) on microbiology regarding the population of LAB, molds, and yeasts. LAB numbers peaked at 6.34 log10 CFU/g when using the 4 kg/ha dose in pure corn silage. Inoculation with A. brasilense and fertigation with Si provided higher morphoagronomic yields for the number of live leaves, plant height, ear length with and without husk, green and dry

matter production, grain production, as well as in the C:N ratio. A Si dose of 12 kg ha- 1

is recommended, and for the microbiological population of LAB, molds, and yeast, a Si dose of 4 kg ha-1

is recommended.