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Journal of Applied Sciences
  Year: 2006 | Volume: 6 | Issue: 4 | Page No.: 854-859
DOI: 10.3923/jas.2006.854.859
 
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Differential Expression of Aluminium Tolerance Mechanisms in Cowpea Genotypes under Phosphorus Limitation

E.A. Akinrinde, L. Iroh , G.O. Obigbesan , T. Hilger , G. Neumann and V. Romheld

Abstract:
Research efforts have revealed differences in tolerance to Aluminium (Al) toxicity among cowpea (Vigna unguiculata) genotypes grown on acid soils (pH<5.0) with tolerant genotypes exhibiting higher capacity for Al exclusion than the susceptible ones under P-deficient conditions. Here, we tested the hypothesis that genotypic differences in cowpea growth and development might be negatively affected by P limitation, particularly in Al-susceptible genotypes. Root growth responses of two contrasting (Al-resistant and Al-susceptible) cowpea genotypes, Epace 10 (E10) and Santo Inacio (SI) were studied at 0 and 0 μM Al. Root elongation was followed over the first 96 h of Al treatment and during the initial 48 hours elongation was determined daily. In addition, exudation of carboxylates in apical root zone and modifications of rhizoplane pH by the two genotypes were compared in hydroponics` culture experiments that involved +/-Al treatments at mild (14 days) and severe (21 days) phosphorus (P) limitation stages. Differential genotypic responses were further evaluated in a rhizobox experiment, using an acidic Aerenosol from West Africa (Niger) with low expression of Al toxicity. Strong Al-induced inhibition of root growth occurred at 20 μM Al without genotypic difference, suggesting the need to further test genotypic differences at lower concentrations. Under P limitation, E10 exhibited a stronger expression (relative to SI) of root induced chemical changes (increased rhizoplane pH and citrate exudation in apical root zone) to counteract Al toxicity. Therefore, genotypic differences in performance of E10 and SI on acid mineral soils may be associated with different expression of Al tolerance mechanisms, particularly under conditions of limited P supply.
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How to cite this article:

E.A. Akinrinde, L. Iroh , G.O. Obigbesan , T. Hilger , G. Neumann and V. Romheld , 2006. Differential Expression of Aluminium Tolerance Mechanisms in Cowpea Genotypes under Phosphorus Limitation. Journal of Applied Sciences, 6: 854-859.

DOI: 10.3923/jas.2006.854.859

URL: https://scialert.net/abstract/?doi=jas.2006.854.859

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