Comprehensive Profiling of Phenolic Compounds in White and Red Chinese Bayberries (Morella rubra Sieb. et Zucc.) and Their Developmental Variations Using Tandem Mass Spectral Molecular Networking.

Chemical structural characterization of phenolic compounds from the red ("Biqi") and white ("Shuijing") bayberries was carried out in the present study. With the aid of Global Natural Products Social Molecular Networking (GNPS), 18 flavonoid glycosides and 13 proanthocyanidins (PACs) in bayberry extracts were tentatively identified. Three cyanidin-3-glucoside derivatives (cyanidin-acetylapiosyl-glucoside, catechin-cyanidin-3-glucoside, and gallocatechin-cyanidin-3-glucoside), two quercetin derivatives (quercetin-3-arabinoside and quercetin-3-glucuronide), patuletin-7-glucoside, and individual PACs consisting of (epi)catechin or (epi)gallocatechin units were reported for the first time in bayberry fruits. In addition, "Biqi" exhibited a considerable increase of flavonoid glycoside content together with a dramatic decrease in the content of PACs in mature fruits, while "Shuijing" showed a decrease in levels of PACs but failed to accumulate flavonoid glycosides during fruit development.

Lowbush blueberry fruit yield and growth response to inorganic and organic N-fertilization when competing with two common weed species.

Inorganic N fertilizers are commonly used in commercial blueberry fields; however, this form of N can favor increased weed species' growth, which can ultimately reduce the benefits of fertilization. We hypothesized that chipped ramial wood (CRW) compost is an effective alternative organic fertilizer for blueberry plants when weeds are present, as ericaceous shrub species are generally more efficient in utilizing organic N than herbaceous weed species. In this study, we measured the growth, fruit yield, and foliar N response of lowbush blueberry (Vaccinium angustifolium Aiton) to an application of 45 kg N ha-1 in the form of organic (CRW) or inorganic N (ammonium sulfate) in two areas of a commercial field colonized by either poverty oat grass (Danthonia spicata (L.) Beauv.) or sweet fern (Comptonia peregrina (L.) Coult.). We also assessed the impact of the fertilization treatments on litter decomposition rates. Contrary to our hypothesis, we found no significant increase in blueberry fruit yield or growth using CRW. By contrast, inorganic N-fertilization increased fruit yield by 70%. The effect was higher in the area colonized by D. spicata (+83%) than by C. peregrina (+45%). Blueberry fruit yield was on average twice higher in the area of the field having D. spicata than C. peregrina, suggesting a stronger competition with the latter. However, the increase in D. spicata density from 0-1 to >25 plants m-2 reduced fruit production by three-fold and strongly impacted vegetative growth in both fertilized and unfertilized plots. The impact of increased C. peregrina density was comparatively much lower, especially on vegetative growth, which was much higher in the area having C. peregrina. These patterns are likely due to a lower competition for N uptake with C. peregrina as this species can derive N from the atmosphere. Interestingly, the higher fruit yield in the area colonized by D. spicata occurred even in plots where the weeds were nearly absent (density of 0-1 plant m-2), revealing the influence of unidentified variables on blueberry fruit yield. We hypothesized that this difference resulted from over-optimal foliar N concentrations in the area colonized by C. peregrina as suggested by the significantly higher foliar N concentrations and by the negative correlation between foliar N concentrations and fruit yields in this area. The possibility of an influence of C. peregrina on flowering and pollination success, as well as of unidentified local site conditions is discussed. The tested N-fertilization treatments did not affect foliar N concentrations or litter decomposition rates. Overall, our results show that ammonium sulfate is very effective at increasing fruit yields but that both fruit yields and the efficiency of the N-fertilization treatment are decreased by increased D. spicata density, especially above 25 plants m-2. Although CRW did not significantly enhance fruit yields in the short term, this fertilizer may have a long-term beneficial effect.

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

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.

Diversity of frankiae in root nodules of Morella pensylvanica grown in soils from five continents.

Bioassays with Morella pensylvanica as capture plant and comparative sequence analyses of nifH gene fragments of Frankia populations in nodules formed were used to investigate the diversity of Frankia in soils over a broad geographic range, i.e., from sites in five continents (Africa, Europe, Asia, North America, and South America). Phylogenetic analyses of 522-bp nifH gene fragments of 100 uncultured frankiae from root nodules of M. pensylvanica and of 58 Frankia strains resulted in a clear differentiation between frankiae of the Elaeagnus and the Alnus host infection groups, with sequences from each group found in all soils and the assignment of all sequences to four and five clusters within these groups, respectively. All clusters were formed or dominated by frankiae obtained from one or two soils with single sequences occasionally present from frankiae of other soils. Variation within a cluster was generally low for sequences representing frankiae in nodules induced by the same soil, but large between sequences of frankiae originating from different soils. Three clusters, one within the Elaeagnus and two within the Alnus host infection groups, were represented entirely by uncultured frankiae with no sequences from cultured relatives available. These results demonstrate large differences in nodule-forming frankiae in five soils from a broad geographic range, but low diversity of nodule-forming Frankia populations within any of these soils.

Leaf-area index and light attenuation in rapidly expanding shrub thickets.

There is increasing interest in the changes in ecosystem services that accompany the conversion of grasslands to shrub-dominated communities. Shrub structure and associated effects on the light environment may be especially important in affecting productivity and diversity. Leaf-area index (LAI) and understory light levels of Morella cerifera shrub thickets were assessed on Hog Island, Virginia, USA, at four sites along a soil chronosequence. LAI was estimated from annual leaf litter, with allometric models relating stem diameter to leaf area, with a portable integrating radiometer (LI-COR LAI-2000), and from photosynthetically active radiation (PAR) using the Beer-Lambert law. For the two youngest thickets, LAI estimates from leaf litter (approximately 10.0) approached levels often associated with tropical rain forest. Allometric models estimated LAI values at 9.8 and 12.5 for the same thickets. High LAI in thickets also results in high light attenuation. Light levels within thickets were as low as 0.7% of above-canopy PAR in the youngest thicket. These data suggest that M. cerifera shrub thickets have a very high potential for annual net primary production. Furthermore, extreme modification of the light environment, coupled with heavy shrub litter fall, may exclude potential competitors during thicket establishment and rapidly alter community structure and ecosystem function.