RELATIVE ALUMINUM TOLERANCE OF 10 SPECIES OF GRAMINAE

Ten species (28 genotypes) of Graminae were screened in low ionic strength (2.7x10(-3) M) solution culture for aluminum (Al) tolerance. The Al3+ activity (mu M) that reduced yield by 50% (AlRY50) was determined. The species, in order of increasing Al tolerance (with AlRY50 for the tops shown in parenthesis) were Panicum miliaceum (0.4) < Bromus inermis (1.4) < Phleum pratense (2.3) = Bromus stamineus (2.5) = B. sitchensis (2.5) < Lolium perenne (3.3) = L. x boucheanum (3.9) < Oryza sativa (17). An AlRY50 could not be determined for Agrostsis castellana or Zea mays although both were tolerant (AlRY50 > 20 mu M and mu 10 mu M, respectively). Plant element concentrations were determined in five species. Increasing solution Al concentrations increased Al and decreased magnesium (Mg) and potassium (K) in the tops and roots, decreased calcium (Ca) in the tops, and increased phosphorus (P) in the roots.