Progress in improving aluminium tolerance in the perennial grass, phalaris

Abstract

Aluminium (Al) tolerance of 11 cultivars, breeding populations and accessions of the perennial grass, phalaris (Phalaris aquatica L.), was investigated in low ionic strength nutrient solutions. The populations were chosen to determine whether a program to improve the tolerance of phalaris to acid soils had resulted in improved Al tolerance. Populations derived by backcrossing genes from a more Al-tolerant species, P. arundinacea L. (AT populations), were significantly more Al tolerant than populations based on pure P. aquatica. Smaller levels of improvement in Al tolerance had also been achieved within P. aquatica through a combination of selection in Al solutions and at acid soil field sites. The response of roots and shoots to Al stress was similar. Some differences in ranking were obtained depending on whether Al tolerance was defined by actual growth in Al solution or growth relative to the zero Al treatment. Performance in nutrient solution containing Al was highly correlated with second year yield and persistence at a field site with acid soil high in Al to depth. Actual root dry weight in nutrient solution containing Al gave a slightly higher correlation with the field data than root weight relative to the zero control. A tendency for root dry weight to segregate in the presence of Al was observed in some P. aquatica populations but not in the AT populations. It was concluded that a significant improvement in the Al tolerance of phalaris has been achieved through a program to introgress genes from P. arundinacea into P. aquatica.

Direct measurement of roots in soil for single and mixed species using a quantitative DNA-based method

“…On average, phalaris accumulated more root mass in lime-amended soil relative to that in unamended soil, whereas root mass of weeping grass was generally unaffected by liming. This is consistent with weeping grass being very acid-soil resistant (Haling et al 2010) and phalaris cv Holdfast being a relatively acid-soil sensitive cultivar of phalaris (Requis and Culvenor 2004). High concentrations of aluminium, as measured in the unamended soil, can be toxic to root tips and restrict root growth, particularly that of lateral roots (Haling et al 2010).…”

Characterisation of Sardinian germplasm of the perennial pasture grass Phalaris aquatica

“…Some accessions were also more persistent than the cultivars on a low-fertility soil highly acidic to depth (Sutton site), conditions often resulting in low persistence by P. aquatica (Culvenor et al 2011). Interestingly, one of the denser accessions at this site was tested for Al tolerance in nutrient solution and found to be relatively sensitive (Requis and Culvenor 2004), and its greater persistence at the Sutton site may have been related to higher grazing tolerance.…”