Maize productivity in succession to cover crops, nitrogen fertilization and inoculation with Azospirillum brasilense

ABSTRACT The use of microorganisms in agriculture such as Azospirillum brasilense and the cultivation of cover crops in the off season, together with nitrogen fertilization, may be interesting alternatives to increase crop yield. The objective of this study was to evaluate the growth, production and nitrogen concentration of maize grown in succession to cover crops and their interactions with A. brasilense inoculation and topdressing mineral N fertilization. The experiment was conducted on Oxisol, in randomized block design in split-split-plot scheme with four repetitions. The plots consisted of four cover crops: jackbean (Canavalia ensiformis), dwarf pigeon pea (Cajanus cajan), crotalaria (Crotalaria spectabilis) and spontaneous vegetation. In the subplots, with or without inoculation of A. brasilense in maize seeds, and in the sub-subplots: with or without topdressing N fertilization. It was verified that jackbean can generate increments of up to 8.3% in grains per ear, 6.9% in length of ear and 15.2% in mass of one hundred grains. Consequently, the grain yield was higher in this treatment (18%). The inoculation with A. brasilense and topdressing N fertilization did not generate significant increments in maize production components, as observed for cover crops.

摘要：在农业生产中施用巴西固氮螺菌（Azospirillum brasilense）这类微生物、于非种植季种植覆盖作物并配合氮肥施用，是提升作物产量的潜在可行方案。本研究旨在评估覆盖作物后茬种植的玉米的生长状况、产量及氮素浓度，并探究其与巴西固氮螺菌接种及矿质氮肥追施的交互效应。本试验在氧化土（Oxisol）上开展，采用裂裂区设计的随机区组试验方案，设置4次重复。主区设置4种覆盖作物处理：直生刀豆（Canavalia ensiformis）、矮秆木豆（Cajanus cajan）、美丽猪屎豆（Crotalaria spectabilis）以及自然植被。副区设置玉米种子是否接种巴西固氮螺菌的处理，副副区则设置是否追施氮肥的处理。试验结果表明，直生刀豆处理可使玉米穗粒数提升最高达8.3%、果穗长度提升6.9%、百粒重提升15.2%。因此该处理组的籽粒产量较对照提升18%。正如覆盖作物处理的结果所示，巴西固氮螺菌接种与氮肥追施并未对玉米产量构成因子产生显著提升效果。