Phosphorus efficiency in pasture species, 8. Ontogeny, growth, P acquisition and P utilization of Italian ryegrass and phalaris under P deficient and P sufficient conditions [Lolium multiflorum; Phalaris aquatica]
1994
Kemp, P.D. (Massey Univ., Palmerston North (New Zealand). Dept. of Plant Science) | Blair, G.J. (New England Univ., Armidale (Australia). Dept. of Agronomy and Soil Science)
Plants were grown under P deficient and P sufficient conditions in soil in a glasshouse. At both P levels shoot, root and total biomass and net P uptake per plant by Italian ryegrass were greater than by phalaris when the 2 species were compared on a temporal basis, but when compared on an ontogenetic basis the 2 species were similar. The superior biomass production of Italian ryegrass on a temporal basis was due to its greater seed size and rate of ontogeny. Similarly, the greater P uptake per plant of Italian ryegrass on a temporal basis was driven by its greater plant size and faster root extension rate. The level of vesicular arbuscular mycorrhizal (VAM) infection in the roots of the 2 species was similar under P deficiency but greater in phalaris under P sufficient conditions. Overall, the different temporal responses to P of Italian ryegrass and phalaris were largely related to their different rates of ontogeny and the interrelationship between ontogeny and growth rate rather than to differences in their physiology in relation to P acquisition and utilization.
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