Evaluation and initial selection of Brachiaria spp. accessions for acid soils

Yuseika Olivera Castro
Estación Experimental de Pastos y Forrajes Indio Hatuey, Central España Republicana 44280, Matanzas, Cuba

ABSTRACT
From the hypothesis that the collections of Brachiaria spp. have accessions with adaptive potential for acid soils, the objectives of this thesis were: to determine the variation spectrum of collections of these species based on some quantitative indicators in the initial stage of the selection process; to identify the existence of individuals with potential of adaptation in this type of soil and to select the best individuals according to their general performance. The study was conducted at the Pasture and Forage Research Station “Cascajal”, on an Alitic soil with pH ~ 4,9. Two trials were conducted: the first one, in which a collection of Brachiaria brizantha, formed by 36 accessions, was evaluated, and in the second one, 30 accessions of Brachiaria spp. were studied. For performing the measurements and estimations in the establishment and exploitation stage, the Methodology proposed by the Pasture and Forage Research Station “Indio Hatuey” was used. The analyses were made with the statistical system SPSS version 10.0. When analyzing the results of the PCA, the total variability was proven to be moderately high (68,13) or high (93,60) in any of the established periods regarding the measured and/or estimated indicators; the most variable and, in turn, coincidental indicators in any of the periods were growth rate, leafiness, plant vigor, cover and yield in the rainy season, in both collections. The little affectation by pests and diseases and the other indicators that are involved in plant health showed that these collections were able to adapt to the soil conditions, and were tolerant regarding the exploitation regime to which they were subject, taking into consideration that neither irrigation nor fertilization was used. When performing the automatic classification analysis, in the three evaluated periods, 19 accessions of B. brizantha and 18 accessions of Brachiaria spp. stood out due to their general performance. It is recommended to continue the evaluation of the best accessions, in replicated essays, under simulated grazing conditions, in order to select pre-commercial varieties for these soil types; to include these collections in other contrasting edaphoclimatic conditions to complete the available information and use the methodological aspects considered in this work as a guideline to be followed in future studies with a similar profile.