Description
A synthetic population, referred to as multicross, has been developed from an interspecific mixture of Stylosanthes capitata and S.macrocephala germplasm. This basic population evolved in a farming situation subject to uncontrolled, continuous, heavy grazing. Natural selection and systematically programmed intercrossing among anthracnose-resistant Venezuelan and Brazilian genotypes of S.capitata have played major roles in the subsequent development of this heterogeneous population. Eight anthracnose-resistant Venezuelan and two Brazilian accessions of S.capitata were introgressed into the basic population. Genetic diversity was further increased by adding seed of four selected accessions of S. macrocephala to the synthetic which had already included three accessions from the basic population. The composite was advanced through five generations of bulk seed production to improve its stability, synchronise harvest maturity, and primarily to facilitate natural intercrossing among S.capitata genotypes. The multicross population displayed anthracnose-resistance in the presence of susceptible, infected accessions in field trials conducted over the years since its initial synthesis in 1990.
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Development of a Multicross Cultivars of Stylosanthes spp.
A synthetic population, referred to as multicross, has been developed from an interspecific mixture of Stylosanthes capitata and S.macrocephala germplasm. This basic population evolved in a farming situation subject to uncontrolled, continuous, heavy grazing. Natural selection and systematically programmed intercrossing among anthracnose-resistant Venezuelan and Brazilian genotypes of S.capitata have played major roles in the subsequent development of this heterogeneous population. Eight anthracnose-resistant Venezuelan and two Brazilian accessions of S.capitata were introgressed into the basic population. Genetic diversity was further increased by adding seed of four selected accessions of S. macrocephala to the synthetic which had already included three accessions from the basic population. The composite was advanced through five generations of bulk seed production to improve its stability, synchronise harvest maturity, and primarily to facilitate natural intercrossing among S.capitata genotypes. The multicross population displayed anthracnose-resistance in the presence of susceptible, infected accessions in field trials conducted over the years since its initial synthesis in 1990.
