Caracterização de acessos de desmanthus em resposta à adubação fosfatada

Abstract

Forage legumes applied in animal husbandry systems provides several benefits, either by improving the diet nutritional value, or greater system sustainability, in which the phosphate fertilization is a management tool that can improve crops yield. This study investigated the morphological, productive, and nutritional characteristics, as well as the survival of 7G (D. pernambucanus) and 13AU (D. virgatus) accessions under four levels of phosphate fertilization (0, 50, 100, and 150 kg P2O5). The experiment design consisted of randomized block, with split plots, and four replications. The harvest interval applied was 84 days (09/22/2020; 12/15/2020, 03/09/2021 and 06/01/2021), totaling one (01) year of evaluations. The plants were cut at 40 cm from the ground. Plant height and width, stem diameter, number of leaves per branch and per plant, number, diameter and length of primary branches, width and length of leaves, leaf/stem ratio, dry matter production (DM) and survival were recorded, as well as the chemical composition and in vitro dry matter digestibility were analyzed. In the fourth harvest, Desmanthus plants were taller (113.26 cm) and wider (75.48 cm), with longer (54.03 cm) and thicker (0.25 cm) branches, with greater number of leaves by branches (12.56), and wider (5.43 mm) and longer (6.98 mm) leaves. In the first harvest, plants developed greater number of branches (20.74) and leaves (189.45) per plant. The access 7G were wider (66.2 cm) than the access 13AU (57.8 cm). The level of 150 kg P2O5 promoted taller plants (82.1 cm), greater number of branches (15.3 branches per plant), and greater DM production (333.5 kg/ha). Levels of P and number of harvests interacted (p < 0.05) for primary branch length, branch diameter, number of leaves per branch and leaf length. Plant nutritive value differed (p < 0.05) among harvests and accessions. The greatest presence of condensed tannins was observed in the 7G access. The greatest plant survival was observed during the first harvest (94%). The morphological and nutritive characteristics, DM production and survival of Desmanthus accessions ranged according to harvest, access and phosphorus fertilization.