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

GUSTAVO STRIKER,; PEDRO INSAUSTI; AGUSTIN GRIMOLDI,; ROLANDO LEON,

FUNCTIONAL ECOLOGY

Blackwell

Año: 2006 vol. 20 p. 4 - 10

0269-8463

Summary 1.We studied the differences in root strength of species with contrasting root structural types (the grassPaspalum dilatatumand the dicotLotus glaber), and their relationship with tolerance to simulated cattle trampling under flooding conditions. relationship with tolerance to simulated cattle trampling under flooding conditions. structural types (the grassPaspalum dilatatumand the dicotLotus glaber), and their relationship with tolerance to simulated cattle trampling under flooding conditions. relationship with tolerance to simulated cattle trampling under flooding conditions. We studied the differences in root strength of species with contrasting root structural types (the grassPaspalum dilatatumand the dicotLotus glaber), and their relationship with tolerance to simulated cattle trampling under flooding conditions. relationship with tolerance to simulated cattle trampling under flooding conditions. Paspalum dilatatumand the dicotLotus glaber), and their relationship with tolerance to simulated cattle trampling under flooding conditions. 2.Root strength was analysed through measurement of the pressure required to cause root collapse. The responses of aerenchyma and plant mass to flooding and trampling were studied. root collapse. The responses of aerenchyma and plant mass to flooding and trampling were studied. Root strength was analysed through measurement of the pressure required to cause root collapse. The responses of aerenchyma and plant mass to flooding and trampling were studied. 3.Root aerenchyma increased from 28·0 to 40·2% inP. dilatatumand from 12·9 to19·7% inRoot aerenchyma increased from 28·0 to 40·2% inP. dilatatumand from 12·9 to19·7% in L. glaberunder flooding conditions. The increase in aerenchyma did not affect root strength in the relatively trampling-resistant roots of P. dilatatum: roots crackedat >380 kPa in all treatments. In contrast, roots ofunder flooding conditions. The increase in aerenchyma did not affect root strength in the relatively trampling-resistant roots of P. dilatatum: roots crackedat >380 kPa in all treatments. In contrast, roots of L. glaberwere weaker, crackingat 260 kPa; flooded roots with air spaces irregularly dispersed in the cortex cracked at115 kPa.were weaker, crackingat 260 kPa; flooded roots with air spaces irregularly dispersed in the cortex cracked at115 kPa. 4.Trampling, flooding or their combination did not affect the biomass ofP. dilatatumTrampling, flooding or their combination did not affect the biomass ofP. dilatatum .Conversely, the isolated effects of either trampling or flooding both decreased biomass accumulation inL. glaber. The combination of both treatments killed allLotusplantsL. glaber. The combination of both treatments killed allLotusplants .5.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. Key-words: aerenchyma, flooding, soil compaction 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. Key-words: aerenchyma, flooding, soil compaction 5.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. Key-words: aerenchyma, flooding, soil compactionKey-words: aerenchyma, flooding, soil compaction