Complementary Application of Inoculant in Post-emergence on Soybean Crop

Objective: Inoculation is an important agricultural practice in soybean cultivation that guarantees high productivity without the external input of nitrogen. The objective of this study was to evaluate if the complementary of liquid inoculant (Bradyrhizobium japonicum), via leaf, in different times and different application rates, affects the nodulation, plant growth and soybean productivity.

Study design: A randomized complete block design (RCBD) was used, with four replications, in a 5x3 factorial scheme, evaluating the complementary inoculant application, via foliar (0; 75; 150; 225 e 300 mL ha-1), in three stages of vegetative development of the crop (V2, V4 e V6).

Location and duration of the study: The study was performed in a commercial area, in the municipality of Sinop, in the northern of Mato Grosso State, between October 2017 and February 2018.

Methodology: The cultivation was in soil classified as Red-yellow Latosol with of clayey texture, was in a direct seeding system, using the cultivar NS7901RR. The seeds used were treated and inoculated at sowing, with turfous inoculant and liquid. The experimental units received the complementary applications of inoculant, via pulverization, at 15, 21 and 28 days after emergence, according to the treatment.

Results: It was verify that the different times of application of foliar inoculant, does not condition significant differences to the parameters measured in this study. The complementary inoculant application affected, significantly, the leaf chlorophyll index (P <0.05), as well as the dry matter mass of the plants (P <0.001). Up to 300 mL ha-1, a gradual increase in grain yield was verified.

Conclusion: The complementary supply of liquid inoculant (B. japonicum), via foliar, in different rates application, affects the nodulation and development of the plants and the productive yield of the crop.