Abstract Lotus glaber is a perennial Mediterranean forage legume that has colonised the temperate humid Flooding Pampa of Argentina. It thrives in phosphorus-deficient soils and produces significant herbage increments when fertilised with small amounts of phosphorus. This species has previously responded to phosphorus addition differently than other legumes, and we hypothesised that the response to phosphorus fertilisation should depend on the expression of morphogenic and functional traits such as leaf area, plant biomass allocation, and relative growth rate, associated with a better nutritional status of tissues of high metabolic activity. We compared biomass productivity, morphogenic characteristics, phosphorus status, and phosphorus utilisation efficiency of L. glaber, Trifolium pratense, and Ornithopus micranthus, at different levels of phosphorus fertilisation. The L. glaber phosphorus response pattern combined a higher aptitude to produce biomass in phosphorus deficient soils and a declining nutrient utilisation efficiency when soils are increasingly fertilised. O. micranthus showed the expected response of species from infertile soils, low productivity, no variation in morphological and functional traits, and a low phosphorus demand. In this sense, T. pratense showed opposite behaviour with sustained increase in many traits with P application. Phosphorus concentration and biomass allocation within the plant are involved in this response to phosphorus fertilisation.
Keywords Lotus glaber; Trifolium pratense; Ornithopus micranthus; phosphorus fertilisation; phosphorus utilisation efficiency
New Zealand Journal of Agricultural Research, 2000, Vol. 43: 473-480
0028-8233/00/4304-0473 $7.00/0 (c) The Royal Society of New Zealand 2000