Effect of Aluminum on Uptake & Translocation of Phosphorus by Perennial Ryegrass

Abstract

Uptake of Phosphorus. In the initial experimzent plants 8 weeks old were used in a series of uptake studies. Continuously aerated uptake solutions were contained in foil-wrapped liter beakers, and w-ere adjusted to pH 4.0 to 4.1 using 2 N H2,SO and M Na.,CO. There were two main series of plants: one series was grown without aluminum and aluminum was added to the uptake solutions; the other series w%as pretreated with 1.85 X 10-4 At or 18.5 X 10-4 I Al during growth and had no aluminum in the uptake solutions. Phosphorus was given as NaH.PO4 at 4.5 x 10 i%f and 22.5 x 10 SI P, labeled respectively with 10 and 50 i'c of p32. Assav of Phosphorus. After each uptake period the roots were washed with five successive changes of deionised water, blotted, dried at 800 and weighed. Shoots and roots were ashed in the muffle on stainless steel planchets at 4000, the ash being taken up with dilute nitric acid and evaporated to dryness. The activity was counted with a mica end-windowv counter of 1.5 mg/cm2 thickness.Total phosphorus was estimated by extracting the planchets with dilute nitric acid, adjusting the solution to pH 3.0, and determining phosphorus colorimetrically by stannous chloride reduction of the phosphomolybdate.Inhibitors. In the inhibitor experinment plants were grown in liter beakers for 6 weeks, in the same continuously aerated solution as previously. The solution was changed weekly. The procedure for uptake studies was to transfer the plants to deionised water overnight, then place thenm for 1 hour in appropriate inhibitor solution prior to transfer to the uptake solution. This comprised the full culture medium with 4.5 X 10-4 AI phosphorus labeled witlh 30 /ic of p32, plus aluminum and inhibitor, and the pH adjusted to 4.0 to 4.1. Inhibitors used were 2,4-dinitrophenol (DNP), KCN and MnSO4. Following absorption periods, roots were rinsed once in Au toradiogra phs. For autoradiographic studieF 9 week old plants were subjected to the same procedure as in the inhibitor experiment. For the timecourse studies, roots only were used and tops werc 403 www.plantphysiol.org on May 9, 2018 -Published by Downloaded from

Effect of Aluminum on the Uptake and Metabolism of Phosphorus by Barley Seedlings

“…The uptake of P32 and its incorl)oration into phosphorylated comnpoull(ns wvas examilned in the roots of barley seedlings which had been lpretreated with alumliniulmi.The rate at which phosphortis increased in Al-roots was greater thani ill control,: especially (luriilig the first 15 …”

“…The rate at which phosphortis increased in Al-roots was greater thani ill control,: especially (luriilig the first 15 …”

Mineral composition and dry mass production of the corn plants in response to phosphorus sources and aluminum concentration

“…Al toxicity has been recognized, for a long time, as the main limiting factor of the plant growth in the acidic soils (Hartwell and Pember, 1918;Magistad, 1925). Al reduces the plant development as a whole (Randall and Vose, 1963;Costa et al, 2003) and interferes with the root elongation (Matsumoto and Morimura, 1980), nutrients' uptake, transport and use (e.g. phosphorus -P) (McCormick and Borden, 1972;Adrew and Berg, 1973;McCormick, 1974;Fleming, 1983).…”

Effect of different aluminium and phosphorus levels on aluminium-tolerant and aluminium-susceptible genotypes of white clover (Trifolium repensL.)

“…There was no stimulation of P uptake by Al as has been reported in other species (Ragland & Coleman 1962;Randall & Vose 1963;Macklon & Sim 1992) presumably because the Al treatments exceeded the concentrations where such responses occur. However, at the P50 level, P uptake decreased much more slowly with increasing Al in T77 than in S129 (Table 8).…”

“…These phenomena have been observed in many species and the AIinduced P deficiency is assumed to result from complexing of Al and P in roots (Wright 1943;Wright & Donahue 1953). However, at low levels of AI, P uptake is stimulated in ryegrass (Randall & Vose 1963) and snapbeans (Ragland & Coleman 1962). Malavolta et aI.…”