The effects of aluminium and pH on the growth of a range of temperate grass species and cultivars

Abstract

As part of an on-going programme to identify Al tolerant plant material we compared the tolerance of 13 common temperate grasses (37 cultivars) in 24 experiments over two years in solution culture at low ionic strength (2740 μM). For each cultivar the relationship between solution Al activity {Al^3+} and relative yield was defined and the Al³⁺ associated with a 50% reduction in yield was determined.

Browntop (Agrostis tenais Sibth) and Chewings fescue (Festuca rubra L. subsp. commatata Gaud) were exceptional, being unaffected by Al³⁺ up to 30 and 12 μM respectively. Yorkshire fog (Holcus lanatus L.), Veld grass (Ehrharta calycina Smith) and paspalum (Paspalum dilatatum Poir) were also relatively tolerant to Al with a 50% reduction in top yield (RY 50%) associated with Al³⁺ of 13, 10 and 7 μM respectively. Poa pratensis (Poa pratensis L.), crested dogstail (Cynosurus cristatus L.) and Prairie grass (Bromus wildenowii Kunth.) were all relatively sensitive to Al (RY 50% 1.3, 0.7 and 0.5 respectively).

Three cocksfoot (Dactylis glomerata L.) cultivars exhibited marked differences in tolerance to Al with cv Grasslands Wana being tolerant (RY 50% 5.4), cv Grasslands Apanui sensitive (RY 50% 2.4) and cv Grasslands Kara intermediate. Tall fescue (Festuca arundinacea Schreb.) was intermediate in its tolerance to Al with RY 50% at 3.7 and 4.0 μM Al³⁺ for the two cultivars tested. The cultivars of the ryegrass species Lolium multiflorum Lam. and Lolium hybridum, together with those of Lolium perenne L. derived from European or Australian origins were generally more tolerant to Al (50% RY @ 3.0–4.5 μM Al³⁺) than the New Zealand cultivars of Lolium perenne (50% RY @ 1.5–2.5 μM Al³⁺). A notable exception was Lolium hybridium cv Grasslands Ariki which behaved like the New Zealand Lolium perenne cultivars. Increasing the solution pH from 4.7 to 6.0 had no significant effect on the yield of the temperate grasses examined but significantly decreased yields of paspalum and veld grass.

The results indicate that most of the economically important temperate grasses are sensitive to micromolar concentrations of Al(<5 μM Al³⁺) but that there exists within some species variability to Al stress which could be exploited.