BACKGROUNDSince available arable land is limited and nitrogen fertilizers pollute the environment, cropping systems ought to be developed that do not rely on them. Here we investigate the rapidly growing, N2‐fixing Azolla/Nostoc symbiosis for its potential productivity and chemical composition to determine its potential as protein feed.RESULTSIn a small production system, cultures of Azolla pinnata and Azolla filiculoides were continuously harvested for over 100 days, yielding an average productivity of 90.0–97.2 kg dry weight (DW) ha−1 d−1. Under ambient CO2 levels, N2 fixation by the fern's cyanobacterial symbionts accounted for all nitrogen in the biomass. Proteins made up 176–208 g kg−1 DW (4.9 × total nitrogen), depending on species and CO2 treatment, and contained more essential amino acids than protein from soybean. Elevated atmospheric CO2 concentrations (800 ppm) significantly boosted biomass production by 36–47%, without decreasing protein content. Choice of species and CO2 concentrations further affected the biomass content of lipids (79–100 g kg−1 DW) and (poly)phenols (21–69 g kg−1 DW).CONCLUSIONSBy continuous harvesting, high protein yields can be obtained from Azolla cultures, without the need for nitrogen fertilization. High levels of (poly)phenols likely contribute to limitations in the inclusion rate of Azolla in animal diets and need further investigation. © 2018 The Authors. Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

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This article documents the addition of 229 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Acacia auriculiformis × Acacia mangium hybrid, Alabama argillacea, Anoplopoma fimbria, Aplochiton zebra, Brevicoryne brassicae, Bruguiera gymnorhiza, Bucorvus leadbeateri, Delphacodes detecta, Tumidagena minuta, Dictyostelium giganteum, Echinogammarus berilloni, Epimedium sagittatum, Fraxinus excelsior, Labeo chrysophekadion, Oncorhynchus clarki lewisi, Paratrechina longicornis, Phaeocystis antarctica, Pinus roxburghii and Potamilus capax. These loci were cross-tested on the following species: Acacia peregrinalis, Acacia crassicarpa, Bruguiera cylindrica, Delphacodes detecta, Tumidagena minuta, Dictyostelium macrocephalum, Dictyostelium discoideum, Dictyostelium purpureum, Dictyostelium mucoroides, Dictyostelium rosarium, Polysphondylium pallidum, Epimedium brevicornum, Epimedium koreanum, Epimedium pubescens, Epimedium wushanese and Fraxinus angustifolia.

SUMMARYThe effects of atmospheric NH3 and SO, separately and in combination on the growth and competitive ability of three species of the Violion caninae alliance were investigated. Growth and nutrient concentrations of Viola canina and Arnica montana in mixed culture with Agrostis capillaris were examined in relation to that in monoculture. Seedlings were transplanted into heathland topsoil in pots and placed in open-top chambers for 9 months from autumn to summer, where they were exposed to ambient air, 90 /

SUMMARY The transition of Dutch heathlands dominated by Calluna vulgaris to grass heaths occurs rapidly and is primarily ascribed to nitrogenous air pollution. C. vulgaris and Deschampsia flexuosa were fumigated with 15NH3 and the adsorption of ammonia to the leaf surface as well as the uptake and translocation of ammonia nitrogen was determined after 4 and 9 weeks. There appeared to be little or no NH3‐nitrogen adsorbed to the leaf surface of either species. D. flexuosa took up more NH3 per unit shoot weight, especially during the first 4 weeks of fumigation. The proportion of nitrogen in the shoots of C. vulgaris taken up as NH3 was approximately 6% and 15% after 4 and 9 weeks exposure to NH3, respectively, while corresponding proportions for D. flexuosa were approximately 17% and 28%. The nitrogen fraction derived from the foliar uptake of NH3 was a factor 1·5 higher in the roots of D. flexuosa than in the woody parts and roots of C. vulgaris after 9 weeks fumigation. Regular spraying with tap water did not influence the concentration of nitrogen or that of cations in either species. The uptake and allocation of NH3‐nitrogen in the two species is discussed in relation to growth and consequences for competition in the field.