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

Abstract

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.

The Development of Endomycorrhizal Root Systems: I. Spread of Infection and Growth‐promoting Effects With Four Species of Vesicular‐arbuscular Endophyte

“…This result is in agreement with the findings of Brewster, Bhat and Nye (1975a, b) who suggested that this could be caused by inter-root competition for phosphate, which becomes more serious with time as roots become clumped at the sides and bottoms of the pots, and/or a general change in root absorbing properties with increasing physiological age of the plant. The latter has been demonstrated in solution culture with constant phosphate concentration (Christie and Moorby, 1975;Brewster et al, 1975a). Inflows to root systems infected with LAM, YV and BR endophytes were increased above those to control roots even at low percent infections.…”

Component growth efficiencies of mycorrhizal and nonmycorrhizal plants

“…Seeds, for example, often have lower PUE than stems because seeds require more P to produce a given d. wt than do stems. Variation in PUE also occurs among plant species (Christie & Moorby, 1975 ;Haynes et al, 1991), and as a consequence of *Author for correspondence (fax j1 814 863 6139 ; e-mail rxk13!psu.edu). variation in P availability and mycorrhizal colonization (Chapin, 1980 ;Haynes et al, 1991 ;Koide, 1991).…”

Analysis of the response of pasture legumes to phosphorus in a controlled environment

“…Growth analysis, which can be used to describe some of these, has been used in attempts to understand differences in response to phosphorus (P) among species (Barrow 1975(Barrow , 1977 Biddiscombe et aI. 1969; Christie & Moorby 1975; Keay et aI. 1970;White 1972White , 1973 and to develop a model for P uptake and plant growth (Nye et aI.…”