Establishment of Urochloa brachyura</i)(Hack.) Stapf and its potential role in planted pastures and reclamation

Abstract

>The selection and development of species adapted to extreme conditions is very important for sustainable production in South Africa. This is due to South Africa¡¦s limited natural resources, low and unpredictable rainfall, and ever-increasing human population. The need for an increase in livestock production, collapsing grain markets and the difficulty of profitable maize production, places more importance on the role planted pastures will play in the future. Urochloa brachyuran is an annual tropical grass collected in Gauteng Province and selected for yield and quality. Seed harvested in 1999/2000 generally had a poor germination performance. This prompted an investigation into possible causes for poor germination and ways of improving seed quality. Investigating drying procedures, showed that drying temperatures between 20„aC and 45„aC did not have an effect on the quality of the seed. Several dormancy-breaking procedures were carried out with no success, although, applying a temperature treatment of 45„aC for three weeks, increased germination to between 30 and 40%. It was found that emergence of seedlings where seed was covered with soil, was significantly better than the control which was not. The highest germination was found when seeds were planted 30 mm deep. Conducting a water stress experiment proved that water deficits had a definite negative influence on the dry matter production and the seed production of U. brachyuran and can thus have a strong negative impact on the successful re-establishment of this annual species in water stressed conditions. A trial to evaluate dry matter production over three seasons was conducted in Pretoria. Representative samples were analysed for crude protein content and in vitro digestibility. The potential seed production was also evaluated over two seasons. Dry matter production results confirm results reported by Pieterse (1999), with an average total production of 14.3 t/ha, a digestibility of 74.9%, and a crude protein content of 12.3%. An average of 305kg seed/ha was produced over two seasons. The potential that U. brachyuran already holds for use in rehabilitation practices because of its fast, low growing habit, was further evaluated by the determination of the influence of saline mine water on germination and dry matter production. The results suggest that U. brachyuran can successfully be irrigated with saline mine water. It can be concluded from the results of this project that U. brachyuran can be successfully incorporated in animal production systems and rehabilitation practices.