Relationship between the Al resistance of grasses and their adaptation to an infertile habitat.
OBJECTIVE
Original data on Al resistance, relative growth rate and leaf traits of five European grasses as well as literature data on Al resistance, habitat preference and traits of grasses were considered to determine whether (a) Al resistance is correlated to a growth conservative strategy and (b) species occurrence could be useful to assess Al toxicity in meadows on acid soils.


METHODS
The Al resistance of 15 species was represented by the Al activity in nutrient solution that resulted in a 50 % decrease in root length, [Al(3+)](50), or, for published values, in root or plant biomass. The correlations between Al resistance and acidity or nitrogen indices and the correlation between Al resistance and selected traits (relative growth rate, leaf dry matter content, specific leaf area and leaf thickness) were calculated. Principal component analysis was used for the characterization of the relationships between Al resistance and measured traits.


RESULTS
The [Al(3+)](50) values of the resistant species Molinia caerulea and Sieglingia decumbens were 13 and 26 microm [Al(3+)](50), respectively. The known Al resistance of 15 species that were mainly of the intermediate strategy competitor-stress tolerator-ruderal (C-S-R) type and of the S type was correlated with Ellenberg's nitrogen and acidity indices. For the whole set of species, the correlation between Al resistance and traits was not significant.


CONCLUSIONS
The Al resistance of the C-S-R species was variable and independent of their traits. S-type species, adapted to acid soils and with traits of conservative strategy, displayed Al resistance. The large difference in Al resistance between grasses may help assess Al soil toxicity by using the abundance of grasses.
Poozesh
Vahid
V
UMR 1248 Agir, INRA-ENSAT, BP 52627 Auzeville, 31326 Castanet-Tolosan, France.
Cruz
Pablo
P
Choler
Philippe
P
Bertoni
Georges
G
D000064:Acclimatization; D000143:Acids; D000222:Adaptation, Physiological / Q000187:drug effects*; D000535:Aluminum / Q000633:toxicity*; D004351:Drug Resistance; D017753:Ecosystem; D006109:Poaceae / Q000187:drug effects / Q000502:physiology*; D012987:Soil
D000143:Acids; D012987:Soil; D000535:Aluminum