Agronomic performance and sweet corn quality as a function of inoculant doses (Azospirillum brasilense) and nitrogen fertilization management in summer harvest

ABSTRACT The inoculation of sweet corn seeds with Azospirillum brasilense in association to nitrogen fertilizer may be an agronomic alternative for increasing the crop yield and net income of plant growers. Therefore, the aim of this study was to investigate the effect of the different doses of inoculant (Azospirillum brasilense) associated to the nitrogen fertilization management on the phenotypic traits of one sweet corn hybrid in summer growing periods, under supplemental irrigation, in the Northwestern Paraná state, Brazil. The experiment followed the complete randomized block design with four replications. The treatments were: i) five inoculant doses (0.0, 50, 100, 150 and200 mL∙ha–1) containing Azospirillum brasilense; ii) two N doses (0.0 and 30.0 kg∙ha–1) applied at sowing time; and iii) two topdressing doses of N (0.0 and 110.0 kg∙ha–1) applied at the V4 stage. The sweet corn hybrid RB 6324 was evaluated in 2012/2013, 2013/2014 and 2014/2015. The traits plant height (ranged from 2.11 to 2.26 m), leaf area index (3.33 to 4.32), crop yield (7.21 to 10.43 Mg.ha–1), and the sugar kernel contents (38.46 to 43.31%) and protein (12 to 12.81%) were positively influenced by the seed inoculation with A. brasilense, and the nitrogen fertilizer increased all the traits except the kernel total sugars. The dose of inoculant that provided the best agronomic result was 100 mL∙ha–1 in conjunction with the application of N either at sowing or topdressing.

摘要：采用巴西固氮螺菌（Azospirillum brasilense）接种甜玉米种子并配合氮肥施用，或可作为提升作物产量与种植者净收益的农艺替代方案。鉴于此，本研究旨在探究巴西巴拉那州西北部补充灌溉条件下，夏季生育期内不同剂量的巴西固氮螺菌菌剂配施氮肥管理模式，对某甜玉米杂交品种表型性状的影响。本试验采用完全随机区组设计，设置4次重复。试验处理分为三类：①5种菌剂施用剂量（0.0、50、100、150及200 mL∙ha–1），均含有巴西固氮螺菌；②2种基肥施氮剂量（0.0与30.0 kg∙ha–1），于播种时施用；③2种氮肥追施剂量（0.0与110.0 kg∙ha–1），于V4生长期施用。供试甜玉米杂交品种为RB 6324，试验分别于2012/2013、2013/2014及2014/2015年开展。测定的表型性状包括株高（2.11~2.26 m）、叶面积指数（3.33~4.32）、作物产量（7.21~10.43 Mg·ha–1）、籽粒总糖含量（38.46%~43.31%）与蛋白质含量（12%~12.81%）。结果表明，巴西固氮螺菌种子接种可正向提升所有测定性状；氮肥施用除对籽粒总糖含量无显著促进作用外，可改善其余所有性状。综合农艺效益最优的菌剂施用剂量为100 mL∙ha–1，配合基肥或追肥施氮均可获得最佳栽培效果。