Abstract

LOPEZ, Marisol; ESPANA, Mingrelia  and  TORO, Marcia. Efficiency of phosphorus absorption in you will cultivate of sorghum of different tolerance from the aluminum toxicity. Agronomía Trop. [online]. 2007, vol.57, n.3, pp.205-218. ISSN 0002-192X.

Five Sorghum bicolor L. Moench cultivars with different tolerance to aluminum toxicity were evaluated. The aim was to determine their phosphate absorption efficiency under greenhouse-controlled conditions. The evaluated cultivars were four grain sorghum (Chaguaramas III (Ch III), Chaguaramas VII (Ch VII), Dekalb-59 (DK-59) and Criollo-26), and one forage sorghum (Ismael). The experiment was carried out in a low phosphate availability soil (Typic Paleustults). A completely randomized design with factorial arrangement with two factors was used. Treatments were: T1 (control) = 0P (no phosphate applied); T2= RPR (Riecito phosphate rock), and T3 = TSP (Triple superphosphate). A nutrient solution (mg pot^-1) of 58.54 K (KCl-60 % K₂O) and 117 N (Urea-46 %N) was applied to all treatments. Phosphorus dose was 97.56 mg pot^-1, where phosphate sources were Riecito phosphate rock and highly soluble Triple superphosphate. Determinations were made in the rhizosphere: acidic phosphomonoesterase activity, arbuscular mycorrhiza colonized root lenght (%CRL), pH soil-water relation 1:2,5 (in soil and rhizosphere), and phosphate efficiency use. Cultivars that better absorbed and used P showed mechanisms such as > % de CRL and rhizospheric pH increments. This was markedly showed in cultivars tolerant to aluminum toxicity which had higher dry matter yield. However cultivars less efficient in P absorption or use, showed an increased acid phosphatase activity, as a mechanism to grown in acid soils: this was particularly typical in D-59 cultivar, sensitive to aluminum toxicity.

Keywords : Sorghum bicolor L; Moench; phosphateuse efficiency; aluminum toxicity tolerance; rhizosphere; rock phosphate; arbuscular mycorrhiza.