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

Abstract

Summary 1.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. 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. 3. 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 in 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; flooded roots with air spaces irregularly dispersed in the cortex cracked at 115 kPa. 4. Trampling, flooding or their combination did not affect the biomass of P. dilatatum . Conversely, the isolated effects of either trampling or flooding both decreased biomass accumulation in L. glaber . The combination of both treatments killed all Lotus plants . 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.

Physiological and anatomical traits associated with tolerance to long‐term partial submergence stress in the Lotus genus: responses of forage species, a model and an interspecific hybrid

“…In our work, the plants remained in the recovery period for 5 weeks, trying to emulate a field situation in which the forage resource can then be grazed without being detrimental to the survival of the plants. It has been demonstrated that L. tenuis plants with a high proportion of aerenchymatous tissue are severely affected during a post‐flooding‐early grazing due to roots collapse by cattle trampling (Striker, Insausti, Grimoldi, & Leon, ). Our results showed that Lt and LtxLc, which presented the best response under flooding, also performed best during the recovery period (Figure ).…”

Shade affects responses to drought and flooding – acclimation to multiple stresses in bittersweet (Solanum dulcamara L.)

“…Under field conditions, plants are typically exposed to multiple stress factors (Striker et al . ; Valladares et al . ; Anten et al .…”

Trampling enhances the dominance of graminoids over forbs in flooded grassland mesocosms

“…Conversely, flooding rapidly reverts the grazing effects on the plant community by promoting the abundance of flood‐tolerant graminoids and reducing the presence of weed forbs (Insausti et al 1999), most of which are flood‐sensitive species (Grimoldi et al 2005). The legume L. tenuis also persists because of its higher flooding tolerance under conditions that do not involve trampling (Striker et al 2005, 2006). Recently, we identified the grass Paspalum dilatatum as tolerant and some coexisting dicot species (i.e.…”

“…Recently, we identified the grass Paspalum dilatatum as tolerant and some coexisting dicot species (i.e. weed forbs and the legume L. tenuis ) as sensitive to the combination of flooding and trampling (Striker et al 2006, 2007). We demonstrated that the generation of aerenchyma tissue induced by flooding increases the root weakness of the forb species but has no effect on the strength of graminoid roots (Striker et al 2006, 2007).…”