Propagule Orientation Modulates Early Sugarcane Establishment and Responsiveness to Bacillus simplex Inoculation

This study evaluated the isolated and interactive effects of propagule orientation and Bacillus simplex inoculation on early sugarcane establishment under greenhouse conditions. A completely randomized 5 × 2 factorial experiment was conducted with five propagule orientations: horizontal bud position (HOR), vertical bud-up (VUP), vertical bud-down (VDW), inclined bud-up (IUP), and inclined bud-down (IDW), combined with the presence or absence of Bacillus simplex inoculation. Each treatment combination had eight replicates. Bud sprouting, tillering, plant height, shoot biomass, and root biomass were evaluated during establishment. Propagule orientation significantly affected all evaluated variables. Vertical bud-down reduced sprouting, plant height, and biomass accumulation, resulting in the poorest early plant performance. Significant orientation × inoculation interactions were observed for tillering, plant height, shoot biomass, and root biomass. Inoculation increased tillering and plant height mainly under horizontal orientation at 45 days after planting, whereas positive root biomass responses at 80 days after planting occurred mainly under inclined orientations. The strongest response occurred under inclined bud-down, with increases of approximately 34% in root fresh mass and 38% in root dry mass compared with the non-inoculated treatment. Propagule orientation modulated sugarcane responsiveness to Bacillus simplex inoculation during establishment. Vertical bud-down impaired plant performance, whereas horizontal and inclined orientations favored specific inoculation responses at different stages. Propagule positioning should be considered in future field validation studies. Propagule orientation affected early sugarcane establishment and biomass accumulation. Vertical bud-down positioning reduced sprouting, plant height, and biomass production. Sugarcane responsiveness to Bacillus simplex inoculation depended on propagule orientation. Inoculation improved tillering and plant height mainly under horizontal propagule orientation. Inclined orientations, especially bud-down positioning, enhanced root biomass responses to Bacillus simplex inoculation.