Antônio Carlos de Oliveira Junior

Maintaining the productivity and technological quality of sugarcane during ratoon cycles represents a constant challenge for the sugarcane-energy sector, driving the adoption of biostimulants. This study aimed to evaluate and compare the effects of different biostimulants on the biometric development, yield, and technological quality of second-ratoon sugarcane. The experiment was conducted in a randomized complete block design with four treatments and four replications: (1) Control; (2) Ascophyllum nodosum; (3) A. nodosum + nutrients; and (4) Arbuscular mycorrhizal fungus (Rhizophagus irregularis). Tiller density, stalk height, stalk diameter, stalk weight, productivity, total recoverable sugars (TRS), and sugar yield were evaluated. Data were subjected to analysis of variance (Tukey’s test, p ≤ 0.05) and principal component analysis (PCA). Tiller density was not affected by the treatments; however, biostimulation with A. nodosum alone proved to be the most effective treatment, yielding the highest stalk height (2.35 m), stalk weight (1.48 kg), TRS (146.06 kg t⁻¹), and sugar yield (14.52 t ha⁻¹), representing a 19.5% increase in sugar yield compared to the control. Inoculation with R. irregularis matched A. nodosum in productivity but resulted in lower TRS, indicating a sucrose dilution effect. A. nodosum combined with nutrients did not surpass the control across production variables. PCA confirmed the distinct separation and superiority of the isolated A. nodosum treatment along the growth and productivity axis, further demonstrating that these inputs operate through distinct physiological mechanisms. In conclusion, the A. nodosum-based biostimulant (applied alone) constitutes the most promising strategy to simultaneously enhance yield and technological quality in sugarcane ratoon crops.

Although sugarcane yield is directly influenced by the availability of nitrogen (N), the efficiency of mineral N (MN) fertilization is considered to be low due to nitrate leaching and ammonia volatilization. Thus, the search for alternative sources of N that are cheaper and more consistent with sustainable farming practices has been stimulated. As chicken litter is an organic waste with the potential to supply N to major crops, we tested the hypothesis that the use of this litter as a source of organic N (ON) is as efficient as the application of MN (ammonium nitrate) in promoting the growth, nutrition, and yield of sugarcane plants grown during both plant cane and ratoon cane seasons. Experiments were conducted in a 5 × 5 × 2 subdivided plot scheme in the growing area of the Denusa Mill, Destilaria Nova União S/A, located in the midwest region of Brazil, with treatments consisting of five doses each of MN (0, 40, 80, 120, and 160 kg ha⁻¹) and ON (0, 2, 4, 6, and 8 T ha⁻¹), evaluated in two crop seasons (plant cane-2019/2020 and ratoon cane-2020/2021). The application of different doses of MN or ON influenced the height and number of tillers of sugar cane plants, and the application of ON, supplied by chicken litter, to this crop was as efficient as that of MN in promoting plant growth. MN and ON also increased the leaf content of N, P, and K; moreover, the absence of one source of nitrogen was compensated by the other. ON application (up to 4.8 T ha⁻¹) also increased sugarcane yield in addition to promoting growth. Furthermore, this study highlighted the superior quality of the regrowth observed in the IACSP95-5094 cultivar, which manifested in increased tillering and stem diameter, resulting in consistently higher yields in the ratoon crop.