The phenological development of Themeda triandra, Elyonurus argenteus and Heteropogon contortus under field conditions in the central Orange Free State.

Abstract

Range managers must take into consideration the phenological development of plants, especially shoot apex development, when planning pasture management systems. The damaging of the shoot apex by grazing, cutting, fire or drought may have a detrimental effect on leaf, shoot and seed production. The shoot apices of Themeda triandra, Elyonurus argenteus and Heteropogon contortus showed the same tendency with respect to elevation before and during flowering. The shoot apices were not elevated more than 1 cm to 1, 5 cm above the soil level for a period of 11 to 14 months. After the shoot apices become reproductive they are raised slowly 2 to 3 cm above soil level. If soil moisture conditions become favourable flowering occurs in due time. Elyonurus argenteus tends to flower 21 to 28 days earlier than T. triandra and H. contortus. Flowering of T. triandra and H. contortus may occur as late as March if soil moisture conditions are not favourable earlier. The carbohydrate (reserve) content of the stubble of all three grasses decreased rapidly under fluctuation soil conditions that resulted in successive regrowth and dying off of the aerial parts of the plants. The moisture content of the leaves dropped quickly under moisture stress conditions. Elyonurus argenteus compares favourably with T. triandra and H. contortus with respect to their in vitro digestibility and crude protein content.

Keywords: afrikaans; botany; carbohydrate; crude protein content; cutting; digestibility; drought; elyonurus argenteus; fire; flowering; grasses; grazing; heteropogon contortus; in vitro digestibility; moisture content; moisture stress; orange free state; pasture management; production; protein; regrowth; seed production; shoot apex; shoot apices; soil moisture; south africa; themeda triandra