Competition for Phosphate Between a Diploid and a Tetraploid Perennial Ryegrass

Abstract

The relative uptake of P was measured in two varieties of Lolium perenne using radioactive tracer techniques. Tbe diploid cv. Hora and the tetraploid cv. Terhoy were sown as pure stands and as 50:50 mixtures at both high and low density. Uptake from four depths 10, 20, 30 and 40 cm was examined. The results showed tbat: in pure stands the diploid uptake at 10 cm exceeded that of tbe tetraploid altbougb at deeper levels the uptake pattern was similar; in mixtures the uptake of the tetraploid variety increased markedly at 10 cm while that of the diploid variety decreased. The diploid compensated for its decreased uptake at 10 cm by a suhstantiai increase in uptake at 20 cm; overall the tetraploid variety had a deeper pattern of uptake tban the diploid; in general, uptake at high density was greater than that at low density; the mixture showed a greater degree of P utilization than pure stands in the upper layers of the soil; when these two varieties are grown together in 50:50 mixtures the tetraploid is relatively more efficient in taking up P.

Yield and Composition of Orchardgrass, Tall Fescue, and Reed Canarygrass Mixtures1

“…All whole plot treatments were replicated three times. On 15 Nov. 1978 'Orbit' orchardgrass (0), 'Ky 31' tall fescue (F), and 'Rise' reed canarygrass (R) were sown alone and in three binary (O:R, F:R, O:F) and one ternary (O:F:R) mixtures in four consecutive circular rows, using a template (Harries and Norrington-Davies, 1974). Circular rows were 4, 8, 15, and 30 em from the center with 12 plants per row.…”

Phosphate absorption by white clover stolons in pasture

“…Phosphorus (P) uptake by developed pasture is chiefly from the surface soil (Newbould et al 1971;Jackman & Mouat 1972b;Harries et al 1974;Gillingham et al 1980), where virtually all plantavailable P is concentrated. P accumulates in the surface 2-3 cm of soil as a result of cycling processes, fertiliser application to the soil surface, and the very slow rate ofP diffusion in soils (Ozanne 1976).…”

Uptake zones for phosphorus in spring by pasture on different strata within a hill paddock

“…*An objection to the application of 32p withan associated 31 P carrier is that the added31P maysignificantly increase availablesoilP status and subsequently induceenhanced root proliferation (Newbould 1%9;Newbould & Taylor 1964). It was concluded,however, from associatedwork (Gillingham 1978), and allowing forthe spreadofP intoan approximately 5 ern diametersphere (Harries et al 1974), that in this trial the net increasein OlsenP contentof the {}-3 em depth soilat the isotopeplacement siteswould be small compared with the initially high values ( Table I). The concentration of most P uptake activity in this soil zone also meant that although added P may have produced a proportionately largerincreasein OlsenP at the greater soil depths studied, this would not have markedly altered estimated relative root activity compared with that based on measured soil P content.…”