Utilization of Phosphorus Substrates by Contrasting Common Bean Genotypes


Yan, X.; Lynch, J.P.; Beebe, S.E.


Crop Science, Volume 36, Issue 4, p.936-941 (1996)

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Phosphorus deficiency limits common bean ( Phaseolus vulgaris ) production in tropical soils, where P may be bound to recalcitrant organic matter, or with aluminium or iron oxides. A previous study demonstrated that P-efficient genotypes perform well in contrasting soils, suggesting that interactions with specific soil constituents did not account for genetic variation. To confirm this finding, a study was conducted to determine if contrasting bean genotypes differ in their ability to recover P from different P compounds. Six genotypes (Rio Tibagi, Carioca and G2333 (Mesoamerican types) and G19833, G16140 and G12169 (Andean types)) were planted in pots of silica sand in which P was supplied at four levels as KH 2 PO 4 , CaHPO 4 , inositol hexaphosphoric acid (IP 6 ), FePO 4 , or AlPO 4 . Most results could be explained as a function of relative aqueous solubilities of the P sources. KH 2 PO 4 gave the greatest uptake and growth and FePO 4 the least. No differences were observed in the ability of the six genotypes to acquire P from the Al, Fe, or IP 6 sources. Andean genotypes, especially the Peruvian landrace G19833, extracted more P from CaHPO 4 than Mesoamerican genotypes. G19833 was capable of acidifying the rhizosphere more than other genotypes. It is concluded that (i) differential ability to mobilize P from Fe, Al, and organic ligands does not account for genetic variation in P efficiency, and (ii) Andean germplasm has superior ability to mobilize P from Ca sources, which may be useful in utilizing phosphate rock fertilizers.