Abstract

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.

Highlights

  • Lowbush blueberry (Vaccinium angustifolium) is an ericaceous shrub native to eastern North America that grows on disturbed sites [1,2]

  • Blueberry aboveground vegetative biomass production and belowground biomass There was a significant effect of weed species and an interaction between weed density and weed species on lowbush blueberry aboveground vegetative biomass production (Table 2)

  • Lowbush blueberry aboveground vegetative biomass was 30% lower in plots with poverty oat grass (123 ± 30 g m-2) than in plots with sweet fern (178 ± 33 g m-2)

Read more

Summary

Introduction

Lowbush blueberry (Vaccinium angustifolium) is an ericaceous shrub native to eastern North America that grows on disturbed sites [1,2]. It is an economically significant crop in Quebec, Canada’s Maritimes Provinces and Maine [3], where it is managed for its fruits from naturally occurring plant populations [4]. Lowbush blueberry is well adapted to low nutrient availability and has low N requirements, repeated use of inorganic or organic fertilizers has been shown to increase leaf nutrient concentrations and growth [7,11,12,13,14] as well as fruit yields [11,14,15,16]. Often necessary for fertilizers to be efficient [4,6,11,13,17,18]

Methods
Results
Discussion
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call