Root strength and trampling tolerance in the grass Paspalum dilatatum and the dicot Lotus glaber in flooded soil

STRIKER GG; INSAUSTI P ; GRIMOLDI AA; LEÓN RJC

FUNCTIONAL ECOLOGY

Blackwell publishing

Lugar: Oxford, England.; Año: 2006 vol. 20 p. 4 - 10

0269-8463

We studied the differences in root strength of species with contrasting root structural types, the grass Paspalum dilatatum and the dicot Lotus glaber, and their relationship with tolerance to simulated cattle trampling under flooding conditions. Root strength was analysed through the measurement of the pressure required to cause root collapse. We studied the response of aerenchyma and plant mass to flooding and trampling. Root aerenchyma increased from 28.0 to 40.2 % in P. dilatatum and from 12.9 to 19.7 % in L. glaber under flooding conditions. The increase of aerenchyma did not affect root strength in the relatively trampling-resistant roots of P. dilatatum: roots cracked at > 380 kPa in all treatments. In contrast, roots of L. glaber were weaker, cracking at 260 kPa, and flooded roots with air spaces irregularly dispersed in the cortex, cracked at 115 kPa. Trampling, flooding or the combination thereof, did not affect biomass of P. dilatatum. Conversely, the isolated effect of trampling or flooding both decreased biomass accumulation in L. glaber. The combination of both treatments killed all plants of Lotus. In conclusion, root strength was positively associated with soil trampling tolerance. The effect of aerenchyma tissue generation on root strength varies among root structural types. Aerenchyma tissue increases root weakness in the less stable structural type of the dicot species, but had no effect on the strength of the grass.