Seleção de acessos de Tithonia diversifolia para fins forrageiros

Abstract

Tithonia diversifolia (Hemsl.) A. Gray is a shrub plant with a high potential for animal feed. The species has high productivity, nutritional quality, edaphoclimatic adaptability, and wide genetic and phenotypic diversity. However, studies on the selection of superior materials for its use as forage are scarce. Thus, we sought to evaluate accessions of T. diversifolia found in Minas Gerais, to select superior materials as a shrub forage resource. Eighteen accessions of T. diversifolia were collected in the cerrado and atlantic forest regions of Minas Gerais. The germplasm bank was deployed in the field in a randomized block design with four replications and arranged in subdivided plots, with 18 accessions being allocated in the plots. In the subplots, four evaluations/cuts were carried out over time. The accessions were evaluated for their structural, physiological, productive, and bromatological characteristics. All accessions of T. diversifolia, compared to other forage species, showed high productivity, ranging from 31,000 to 60,000 kg ha-1 of dry matter, in four cuts in the year. They also presented high crude protein (CP) contents between 13.2 and 18.3% and fiber contents within the recommended limits for forages. Accessions MC, DIA, PM, NL, and SRS showed characteristics of higher forage productivity, CP productivity, and daily growth rate. The SRS access stood out among the others in the group due to its high productivity. Other groups can serve to improve the species, being the LUZ2 access highlighted for presenting high leaf/stem ratio values. Accessions ERM, PER, VM, LD, and NAZ stand out for presenting higher CP contents, photosynthetic rate, and water use efficiency. The forage production of T. diversifolia was higher in the cuts carried out between spring, summer, and autumn, with a decrease in yield in autumn/winter, probably in response to low temperatures and the reduction in light intensity available at that time of the year.