Crop and Pasture Science Crop and Pasture Science Society
Plant sciences, sustainable farming systems and food quality

Physiological responses of semiarid grasses. I. The influence of phosphorus supply on growth and phosphorus absorption

EK Christie and J Moorby

Australian Journal of Agricultural Research 26(3) 423 - 436
Published: 1975


Experiments were carried out under controlled conditions to investigate the physiological bases for species differences in yield and nutrient responses to variations in phosphorus supply. Buffel grass (Cenchrus ciliaris), and to a less extent Mitchell grass (Astrebla elymoides), showed a much larger yield response to increasing phosphorus supply than mulga grass (Thyridolepis mitchelliana). Mitchell and mulga grasses had much lower relative growth rates than buffel grass. Mulga grass required a lower external phosphorus concentration for optimal growth than Mitchell and buffel grasses; this was attributed to its superior system for absorbing and transporting phosphate from low concentrations, but was not associated with any yield advantage, yield being related more to the photosynthetic than to the nutritional characteristics of the plants.

Differences between species in their external phosphorus requirements for growth and their distribution in semiarid Queensland are discussed.

© CSIRO 1975

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