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- Title
Phosphorus reserves increase grass regrowth after defoliation.
- Authors
Oyarzabal, Mariano; Oesterheld, Martín
- Abstract
Accumulation of P above levels that promote growth, a common plant response called “luxury consumption”, can be considered as a form of reserve to support future growth when the nutrient can subsequently be mobilized. However, the effect of P reserves on regrowth following defoliation has not been demonstrated. We tested the hypothesis that P luxury consumption increases plant tolerance to defoliation. We performed two experiments with four grass species from a continuously grazed temperate grassland in the Flooding Pampa (Argentina). The first experiment, aimed at generating P luxury consumption by fertilization, resulted in one species ( Sporobolus indicus) showing luxury consumption. In this way, we were able to obtain plants of S. indicus with similar biomass but contrasting amounts of P reserves. The second experiment evaluated the subsequent regrowth following defoliation on a P-free medium of these plants differing in P reserves. Regrowth was larger for plants that had shown P luxury consumption during a previous period than for plants with lower levels of P reserves. During regrowth these plants showed a clear pattern of P remobilization from the stubble, crown, and root compartments to the regrowing tissue, in addition to a likely reutilization of P present in leaf-growth zones. This work is the first showing that high levels of P reserves can confer tolerance to defoliation by promoting compensatory growth under P deficiency.
- Subjects
PHOSPHORUS; NONMETALS; PHOSPHORUS in soils; GRASSES; RANGE plants; DEFOLIATION
- Publication
Oecologia, 2009, Vol 159, Issue 4, p717
- ISSN
0029-8549
- Publication type
Article
- DOI
10.1007/s00442-008-1263-z