Agronomic evaluation of Brachiaria spp. accessions under agroecological conditions of Barrancabermeja, Santander, Colombia

Emiro Rafael Canchila Asencio

ABSTRACT
An evaluation was carried out with 24 Brachiaria spp. accessions in order to select the ones with better response under the conditions of acid and low fertility soils of the Barrancabermeja region, using 72 plots of 21 m2. The germination was carried out in a nursery with sexual seeds. At 138 days after being sown, and after a homogenization pruning, the first year of evaluation started with cuttings every 42 days until 390 days. In the second year the same cutting interval was maintained until carrying out six of them. In the first year the emergence percentage, cover percentage, plant height, forage production, leaf percentage and incidence of pests and diseases were determined. In the second year the same indicators were evaluated, except the first two ones. The analyses were carried out by means of the statistical pack SPSS 10.0. According to the PCA the most variable indicators were: height, forage production, leaf percentage, emergence percentage, incidence of pests and diseases and cover percentage; and in the second year, the height, forage production, leaf percentage and incidence of diseases. In the first year B. dictyoneura (CIAT-6133), B. brizantha (CIAT-16488, CIAT-16212, CIAT-26318, CIAT-16121, CIAT-16113 and CIAT-16322), B. decumbens (CIAT-606) and B. humidicola (CIAT-26159) stood out. In the second year the same accessions were ratified as outstanding, except B. brizantha CIAT-16113 and CIAT-26318 and B. humidicola CIAT-26159. The least adapted accessions were B. ruziziensis CIAT-26180, B. brizantha CIAT-16315, CIAT-16327 and CIAT-6387, B. decumbens CIAT-16497 and B. humidicola CIAT 26159, CIAT-16871, CIAT-16867 and CIAT-26427. No important variations were found in the bromatological composition. The accessions with better growth were for the stoloniferous plants, B. dictyoneura CIAT-6133, for the ones of pro-decumbent habit, B. decumbens CIAT-606 and for the ones of erect growth, B. brizantha CIAT-16113, CIAT-26110 and CIAT-16322. According to the results, it is recommended to disseminate progressively in the region the accessions B. brizantha CIAT-16322, CIAT-16212, CIAT-16121 and CIAT-16488, B. decumbens CIAT-606 and B. dictyoneura CIAT-6133.