Phosphorus Acquisition from Sparingly Soluble Forms by Maize and Soybean in Low - and Medium - P Soils using ~(32)P

摘要

A glasshouse pot experiment was conducted to evaluate the differential ability of maize (Zea mays) and soybean (Glycine max) to utilize soil phosphorus (P) for plant growth from total P, available P and inorganic (Ca-P, Al-P and Fe-P) soil P pools using a carrier-free ~(32)P solution. A maize variety (DK 315) and a soybean variety (TGX 1910-4f)were grown in pots containing 1 kg of a low available P soil (Hungarian) or a medium available P (Waldviertel) soil labelled with ~(32)P for 42 d or without ~(32)P (unlabelled) for 42 and 60 d. The shoot and root biomass of maize and soybean were significantly greater when grown on the Waldviertel than on the Hungarian soils. The shoot P concentrations were higher for soybean (1.7-2.2 g/kg) than for maize (1.1-1.4 g/kg). The total radioactivity (dpm x 106) was higher in plants grown in Waldviertel than in Hungarian soil and the values reflected in the plant P uptake and shoot biomass of soybean and maize. The L-values (ug^P-g-soir1) of maize and soybean werehigher in Waldviertel (72-78) than in Hungarian (9.6-20) soil. No significant differences in L-values were observed for maize and soybean grown on the Waldviertel soil, but for the Hungarian soil, the L-values were higher for maize (20.0) than for soybean (9.6), suggesting that in this low P soil, maize was more efficient than soybean in taking up soil P. The available P (Bray II) and the Ca-P were the fractions most depleted by plants followed by the Fe-P fractions in the two soils, but differences between the crops were not significant. When soil P is limited, maize and soybean are able to access P mainly from the avail-le P (Bray II), and the sparingly soluble Fe- and Ca-P fractions, and Al-P from the soil.