Physiological responses of semiarid grasses. II.* The pattern of root growth in relation to external phosphorus concentration

Abstract

The effect of the external phosphorus concentration on the pattern of root development in mulga, Mitchell and buffel grasses was examined.

During seedling and early vegetative growth, the pattern of root growth suggested that the emergence of axes, their extension and branching were coordinated in such a way that the mean rate of extension and distance between branches remained fairly constant for each component of the root system. Phosphorus deficiency did not greatly affect the length of the seminal axis or the number of its primary laterals, but resulted in a significant reduction in the length of these laterals; the length and number of nodal roots were also greatly reduced.

Species differences in the pattern of root development are discussed in relation to seedling drought survival on infertile soils.

*Part I, Aust. J. Agric. Res., 26: 423 (1975).