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Contrasting impacts of two weed species on lowbush blueberry fertilizer nitrogen uptake in a commercial field

Marty Charles, Lévesque Josée-Anne, Bradley Robert L., Lafond Jean et Paré Maxime C.. (2019). Contrasting impacts of two weed species on lowbush blueberry fertilizer nitrogen uptake in a commercial field. PLoS ONE, 14, (4), e0215253.

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URL officielle: http://dx.doi.org/doi:10.1371/journal.pone.0215253

Résumé

Numerous studies have speculated that lowbush blueberry (Vaccinium angustifolium) is less efficient than weed species at taking up inorganic nitrogen (N) derived from fertilizers, thus raising questions as to the effectiveness of N fertilization in commercial fields. However, competition for acquiring N as well as specific interactions between blueberry and companion weeds characterized by contrasted functional traits remain poorly documented. Here, we assessed fertilizer-derived N acquisition efficiency and biomass production in lowbush blueberry and two common weed species that have different functional traits—sweet fern (Comptonia peregrina), a N2-fixing shrub, and poverty oat grass (Danthonia spicata), a perennial grass—in a commercial blueberry field in Québec, Canada. In 2015, 15N-labelled ammonium sulfate was applied at a rate of 45 kg ha-1 to 1 m2 field plots containing lowbush blueberry and one of the two weeds present at several different density levels (0 to 25 plants m-2). In 2016, each plot was harvested to determine vegetative biomass and the percentage of fertilizer-derived N recovered (PFNR) in each species. The PFNR was higher in blueberry (24.4 ± 9.3%) than in sweet fern (13.4 ± 2.6%) and poverty oat grass (3.3 ± 2.9%). However, lowbush blueberry required about four times more root biomass than sweet fern and poverty oat grass to uptake an equivalent amount of N from ammonium sulfate. The PFNR in poverty oat grass increased with plant density (from 0.8% to 6.4% at 2–3 and >6 plants m-2, respectively), which resulted in a decrease in blueberry’s PFNR (from 26.0 ± 1.4% to 8.6 ± 1.8%) and aboveground vegetative biomass production (from 152 ± 58 to 80 ± 28 g m-2). The increase in biomass production and N content in sweet fern with increasing plant density was not accompanied by an increase in PFNR (29.7 ± 8.4%), suggesting an increasing contribution of atmospherically-derived N. This mechanism (i.e., N sparing) likely explained blueberry’s higher biomass production and N concentration in association with sweet fern than with poverty oat grass. Overall, our study confirms lowbush blueberry low efficiency (on a mass basis) at taking up N derived from the fertilizer as compared to weeds and reveals contrasted and complex interactions between blueberry and both weed species. Our results also suggest that the use of herbicides may not be necessary when poverty oat grass is present at a low density (<15 plants of poverty oat grass m-2) and that adding inorganic N fertilizer is counterproductive when this species is present at a high density as it takes up as much fertilizer as lowbush blueberry.

Type de document:Article publié dans une revue avec comité d'évaluation
ISSN:1932-6203
Volume:14
Numéro:4
Pages:e0215253
Version évaluée par les pairs:Oui
Date:2019
Identifiant unique:10.1371/journal.pone.0215253
Sujets:Sciences naturelles et génie > Sciences appliquées > Agronomie
Sciences naturelles et génie > Sciences naturelles > Biologie et autres sciences connexes
Département, module, service et unité de recherche:Départements et modules > Département des sciences fondamentales
Mots-clés:Vaccinium angustifolium, lowbush blueberry, fertilization, nitrogen, weed, Comptonia peregrina, Danthonia spicata, competition, bleuet nain, fertilisation, azote, plantes indésirables, compétition
Déposé le:17 avr. 2019 00:08
Dernière modification:17 avr. 2019 00:08
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