Variation in foliar inorganic phosphorus concentrations in perennial ryegrass (<italic>Lolium perenne</italic> L.)

Breeding ryegrass for reduced inorganic phosphorus (Pi) concentrations in leaf vacuoles could lower pasture P fertiliser requirements with economic and environmental benefits. We investigated foliar Pi% accumulation characteristics of a range of ryegrass cultivars and ecotypes in glasshouse experiments, and ryegrass cultivars from two field trials. Pi in ryegrass was also compared with Pi in cocksfoot, tall fescue, prairie grass and <italic>Phalaris</italic> in a glasshouse experiment. Pi expressed as a percentage of leaf total phosphorus was higher (average 82.5%) in the older ryegrass cultivars – Ruanui, and Nui and the New Zealand hill country ecotypes (85%) than in more recently bred cultivars like Aberdart and One50 (74.7%). In the other grass species, foliar Pi% was lowest in prairie grass, intermediate in tall fescue with the highest values in cocksfoot, <italic>Phalaris</italic> and ryegrass. The results suggest that including a lower Pi concentration in future ryegrass breeding programmes might improve ryegrass P use efficiency without compromising growth rates. [ABSTRACT FROM AUTHOR]