Difference in the retention of Ca and Al as possible mechanisms of Al resistance in upland rice uri icon

abstract

  • Genotypic differences between upland rice (Oryza sativa L.) varieties in the resistance to acid soil conditions were investigated in terms of the contents of Ca and Al in the apoplast of root tips. Apoplastic Ca and Al contents are assumed to be directly related to the inhibition of root cell elongation, which is the most typical symptom associated with cultivation in acid soils. The apoplastic content of Al eluted with BaCl(2) was significantly different between the tolerant (Oryzica Sabana 6: SB6) and susceptible (Oryzica 1: OZ1) varieties when the Al concentration in the growth solution was in the range of 30 to 100 muM The apoplastic Al content in SB6 was lower, probably reflecting the lower root CEC. On the other hand, the apoplastic Ca content showed significant genotypic differences when Ca was eluted with chelating solutions (Na-citrate and Na-EDTA) rather than with a BaCl(2) solution. The apoplastic Ca content of OZ1 was much higher than that of SB6 in the absence of Al, but it decreased by half when the Al concentration increased to 30 muM, and then decreased further at higher Al concentrations. The apoplastic Ca content of SB6 was low even in the absence of Al treatment, and it did not decrease much further. The effect of solution Al on the Ca content in the root cell walls in the root elongation zone was examined in relation to the varietal differences between upland rice varieties in the resistance to acid soils.

publication date

  • 2003
  • 2003