SELF-INCOMPATIBILITY SYSTEM IN THE ETIllOPIAN POPULA· TIONS OF GUIZOTIA ABYSSINICA (L.F.) CASS. (NIGER)

Abstract

Self-incompatibility (sl) in the Ethiopian populations of Guizotia abyssinica (niger) was studied and detailed genetic analysis was performed. Experiments involving 1425 pollinations were carried out both by petri-dish technique and in situ pollination of the heads. The pollination patterns were recorded. In most cases, SI is believed to be controlled by a single S-Iocus (the recording of 4 self-incompatible mating groups) in the populations of G. abyssinica dealt with by this study. An additional S-locus, I. is proposed as part of the SI system in this crop; this is based on the recording of more than 4 selfincompatible
mating groups in a considerable number of the populations studies.
The type of incompatibility is found to be sporophytic. Pseudocompatibility and seeds obtained from pseudocompatible crosses were characterized. The SI system in G. abyssinica is characterized by the presence of two- and one-way incompatibility,
reciprocal difference, and self-compatibility. Natural selection may favour the establishment of self-compatible genotypes in the populations of Guizotia abyssinica. The frequency of self-compatible genotypes is of a various magnitude in the Ethiopian populations of G. abyssinica originated from different collecting localities.