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Open Access Publications from the University of California

Department of Plant Sciences

UC Davis

Variations in phosphorus acquisition from sparingly soluble forms by maize and soybean in low- and medium-P soils using P-32


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 Ca-P) soil P pools using a carrier-free 32P 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 (Hungarian) and a medium available P (Waldviertel) soils labeled with 32P for 42 days or without 32P (unlabelled) for 42 and 60 days. 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-1) than for maize (1.1-1.4 g kg-1). The total radioactivity (dpm x 106) was higher in plants grown in Waldviertel than in Hungarian soil and the values reflected on the plant P uptake and shoot biomass of soybean and maize. The L- values (μgP .g soil-1) of maize and soybean were higher 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, 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 to take 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. Maize and soybean grown on medium-P soil had a lower specific radioactivity (KBq 103. mgP-1) in shoot than those grown on the low-P soil indicating that plants were using P from the inorganic soil P pools.

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