Variation in tolerance in Phalaris aquatica L. and a related species to aluminium in nutrient solution and soil

Abstract

The range of aluminium tolerance in P. aquatica and P. arundinacea L. was examined and compared with the range in some crop and pasture species of known tolerance. In nutrient solution and aluminium-toxic soil, a distinct class of P. aquatica plants extremely sensitive to aluminium was resolved. The tolerance of each P. aquatica line was correlated with the frequency of sensitive plants, which ranged from 0 to 100%. Significant variation in tolerance remained after exclusion of the sensitive class. The aluminium concentration in nutrient solution required for 50% growth reduction varied from approximately 2 to 6 ppm Al among P. aquatica lines. The more tolerant lines, which included Sirosa and Sirolan, were markedly less tolerant than cocksfoot, tall fescue, subterranean clover and known tolerant cereal cultivars. Root extension was the most sensitive character. However, ranking of P. aquatica lines according to yield in solution gave better agreement (r = 0.81, P < 0.01) with ranking according to relative yield in unlimed versus limed aluminium-toxic soil than did root extension in solution (r = 0.69, P < 0.01). Reference to yield is thus considered necessary for selection among more tolerant plants in a breeding program. The aluminium tolerance of P. arundinacea was superior to that of P. aquatica, and P. arundinacea CPI 69103 was as tolerant as tall fescue in aluminium solutions. Significant improvement of P. aquatica appears possible in the longer term by hybridisation with P. arundinacea, whereas limited improvement should be achieved in the short term by intraspecific recombination and selection.

Progress in improving aluminium tolerance in the perennial grass, phalaris

“…All were relatively sensitive to Al but were more tolerant than CPI19268 (contrast 9). Culvenor et al (1986a) observed the segregation of root growth in Al solutions into sensitive and tolerant classes. Considerable variation between individual plants within populations was also observed in the present experiment.…”

“…Productive hybrids which combine the summer-active growth of P. arundinacea with the winter-active growth of P. aquatica have been created (Carlson et al, 1996). Accessions of P. arundinacea which included both hexaploid and tetraploid races were found to have much higher tolerance of Al in nutrient solution compared with P. aquatica (Culvenor et al, 1986a). An F 1 hybrid between the two species (cv.…”

“…The realisation that strongly acid soils limit the usefulness of phalaris as a pasture species prompted a breeding program to improve its acid soil tolerance (Oram et al, 1993). Phalaris was found to be relatively sensitive to Al in nutrient solution (Culvenor et al, 1986a) but useful heritable variation in tolerance was demonstrated (Culvenor et al, 1986b). Selection for Al tolerance in solution resulted in marginal improvement in acid soil tolerance in cv.…”

Grass establishment and performance on a high country soil fertilised with nitrogen

“…The poor performance of Maru in the second year despite good numbers of plants was most likely because of its intolerance of the low soil pH and potentially high aluminium (AI) (Culvenor et al 1986). The fact that Maru grew well in the first spring suggests that if AI toxicity was the problem, it did not develop until the roots had reached the subsoil.…”

Introduction, production, and persistence of five grass species in dry hill country

“…Phalaris failed to establish and may be intolerant of soil aluminium (Culvenor et al 1986) at the level present in many high country soils. In the mixed grass treatment there were occasionally plants of tall Although freedom from grazing during summer had the expected effect on autumn herbage accumulation, the increase was small because of normally dry summer conditions.…”