Evidence on the response of Patagonian forage grasses to the mulching effect of recent tephra deposits in Argentina.

EDWARDS PRISCILA; VARELA SANTIAGO A.; LOPEZ DARDO R. ; WILLEMS PRISCILA; LOPEZ ALDANA S.; GYENGE JAVIER E.

ARID LAND RESEARCH AND MANAGEMENT

TAYLOR & FRANCIS INC

Lugar: Londres; Año: 2017

1532-4982

The aim of this study was to test whether superficial deposition of volcanic tephra affects pot 24 moisture (% v/v), plant growth, gs (stomatal conductance), and plant gs recovery capacity, of two of the most 25 prominent Patagonian forage grass species (Poa ligularis and Pappostipa speciosa var. speciosa), under two 26 contrasting water regimes. Pots with P. ligularis and P. speciosa were kept under wet (W) and dry (D), tephra 27 absence (T-) and presence (T+) conditions for 105 days, then were all well watered. Pot moisture and plant gs28 were measured periodically. The number of leaves and tillers were assessed, as well as biomass fractions. All 29 variables were compared using factorial models. Water regime had a significant effect on both species 30 performance and gs. The presence of tephra decreased water evaporation from soil, increased pot moisture in 31 wet conditions, increased P. ligularis gs in wet conditions, decreased senescence in dry conditions, allowed 32 roots to grow into it and was associated with gs recovery after dry conditions. Poa ligularis was  more affected 33 by tephra than P. speciosa, probably due to its water stress tolerance strategy and phenotypic plasticity. This 34 may increase species resilience and resistence to periods of water shortage.