BREEDING WARM-SEASON GRASSES TO IMPROVE SEED YIELD AND QUALITY

CARLOS A. ACUÑA

Pergamino

Congreso; 9TH INTERNATIONAL HERBAGE SEED CONFERENCE; 2017

INTERNATIONAL HERBAGE SEED GROUP

Although most forage cultivars of warm-season perennial grasses are able to produce large amounts of biomass they conserve undesirable agronomic characteristics, which are common in undomesticated species. Low seed yield and quality are among them, and they limit the adoption and widespread of many species and cultivars. The objective of this presentation is to analyze different breeding attempts to genetically improved seed related traits in tropical and subtropical grasses. Long flowering periods and seed shattering are common in warm-season grasses, and they are determinant for low seed yields. Attempts have been made trying to shorten the reproductive phase resulting in forages with higher seed yield and longer vegetative phase. Germplasm with improved seed retention has been developed for several species and the involved physiological aspects will be discussed. Since many cultivated tropical forages are polyploid seed fertility tends to be low. The occurrence of apomixis in many of them seems to help to overcome this issue. The presence of dormancy is common in tropical grasses, and this characteristic result in a slow establishment. The main anatomical and physiological aspects related with seed dormancy will be considered. Cultivars with fast germination have been obtained for a few species with a successful outcome. Among the most influential biotic factors affecting seed quality is ergot (caused by Claviceps spp.). Although there is a markedenvironmental effect over the ergot occurrence, cultivars with an improved tolerance to this disease has been generated. The different degrees of success resulting from attempting to improve seed yield and quality will be considered for the most important genus among cultivated warm-season grasses, i.e., Panicum, Brachiaria, Setaria, Chloris, Cenchrus, and Paspalum.