CONICET | Buscador de Institutos y Recursos Humanos

We focused on the following questions: i) whether reductions in root:shoot ratio possess a cost in terms of nutrient balance of the plant and ii) whether changes in resource allocation patterns are proportional among different resources. Our approach was to analyze the variations in the allocation pattern as induced by soil waterlogging. A pot experiment was conducted to analyze the effects of waterlogging upon biomass, phosphorus (P) and nitrogen (N) accumulation of Paspalum dilatatum and Danthonia montevidensis, two waterlogging-tolerant grasses. When changing from oxic to anoxic conditions, a common response of these and other waterlogging tolerant grasses is a reduction in allocation to belowground resources. We observed that: i) the reduction in root:shoot caused by waterlogging did not exert a cost in terms of capacity for nutrient uptake; ii) resource partitioning within aerial parts was less sensitive to treatments than partitioning between roots and shoots; and iii) biomass does not appear to be a useful currency for evaluating nutrient allocation patterns, since the allocation of P and N was inadequately represented by biomass. Our results indicate that the existence of compensation mechanisms reduces the predictive value of the partition of resources on the capacity of plants for acquiring resources. Allocation of nutrients relative to biomass (ARB) data suggest that the assumptions about the independence in the allocation pattern between biomass and limiting nutrients under the effects of environmental factors can be extended.

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