The environment experienced by a plant before and after reproduction can have a profound effect on the behaviour of the progeny after shedding. Maternal environmental effects on seeds are important for phenology and fitness in plants, especially for bet-hedging reproductive strategies. Maternal tissues that disperse with seeds are important for dormancy in many species, particularly those with coat-imposed dormancy and those that disperse in indehiscent fruits. Maternal nitrogen status, temperature and photoperiod modify maternal tissues and also influence the developing zygote. During seed development on the mother, the progeny may acquire environmental information directly, but there is also evidence for maternal–filial signalling and the epigenetic inheritance of environmental information through the germline.

Leaching and volatilization of N from urea, and precipitation and fixing of Zn by commercial fertilizers, has led to excessive costs for farmers and problems for the environment. Incorporating fertilizers in a porous material such as diatomite can prevent these losses by slowing the nutrient release. A new fertilizer formulation, based on the urea-zinc (UZn) complex in the eutectic solution of salt-urea was prepared. In the following, UZn was incorporated into diatomite and nano-diatomite by using hydroxypropyl methylcellulose (HPMC) as a binder. The treatments included the following: U: urea; UZn: urea-Zn; UZn-D: urea-Zn-diatomite; UZn-ND: urea-Zn-nano-diatomite; UZn-D-B: urea-Zn-diatomite-binder; and UZn-ND-B: urea-Zn-nano-diatomite-binder. The slow-release urea fertilizers (SRUFs) were characterized using FESEM/EDS, FTIR, CHN, XRD, DLS, and zeta potential techniques. Urea slow-release behavior, kinetics in water, and available Zn and N-forms leaching in the soil column were evaluated compared with conventional urea and zinc fertilizers. The pattern of release of urea in water was sigmoidal and after 12 h, only 20% of urea was released from fertilizers containing diatomite and HPMC. The NO3– release pattern in the soil started with a 12-day delay, and after that, the rate of NO3– leaching decreased by two to three times in the application of fertilizers containing HPMC compared with urea. The Zn concentration in the leachates of columns supplied with SRUFs was 35% less than for those supplied with ZnSO4. The results showed that the SRUFs make N and Zn available in the soil and but reduce the rate of their release.

In the 12 km2 catchment area of Syv creek, Denmark, moderate to high concentrations of nitrate (NO3−) occurred in the upper part of the oxidized zone (oxic-I), but dropped within the lower suboxic part (oxic-II), to below the detection limit in the unoxidized zone. Structural Fe2+ in the clay minerals made up 10 to 12% of the Fe in the oxidized zone and increased to approximately 50% in the unoxidized zone. Concurrent with changes in the distribution of structural Fe2+ the clay mineral constituents changed. Vermiculite was typically found in the oxidized zone whereas chlorite was found in the unoxidized zone only. A conversion of illite and chlorite into vermiculite seems to take place. A significant correlation between NO3− and the amount of reduced Fe2+ in the suboxic (oxic-II) zone, indicates that primary structural Fe2+ in the clay minerals is the reductant in a NO3− reduction process.

The growing use of nano titanium dioxide (TiO2) in consumer and agricultural products has accelerated its introduction into terrestrial environments, where its impact has not been documented extensively. TiO2 toxicity arises primarily from its ability to photochemically generate reactive oxygen species (ROS), including hydrogen peroxide (H2O2). While common ligands in soil porewaters can either hinder or enhance the degradation of organic contaminants by TiO2, their effects on ROS production by TiO2 have not been understood clearly. The objective of this study was to assess the effect of phosphate (P) and nitrate on UV-irradiated anatase, nano-TiO2. Accordingly, H2O2-generation kinetics experiments were conducted in UV-irradiated TiO2 under environmentally relevant concentrations of the ligands (0, 50, 100, and 250 μM) and pH values (4.00 ± 0.02 and 8.00 ± 0.02) from 0–100 min. Under all conditions, H2O2 grew logarithmically and reached between 5.38 and 22.98 μM after 100 min. At pH 4.00 ± 0.02, H2O2 production was suppressed by P but not by nitrate. Conversely, at pH 8.00 ± 0.02, nitrate did not affect H2O2 concentration while P increased it. Non-specific, minimal adsorption of nitrate prevented interference with the photoreactivity of TiO2. Due to the pH-dependent behavior of suspended TiO2 and H2O2 degradation rates, specific adsorption of P on TiO2 impeded its ability to produce H2O2 photochemically at pH 4.00 ± 0.02 but amplified it at pH 8.00 ± 0.02.

Nitrate is linked to chronic human illness and to a variety of environmental problems, and continues to be a contaminant of concern in soils and natural waters. Improved methods for nitrate abatement, thus, are still needed. The purpose of this study was to assess the potential for redox-modified, iron-bearing clay minerals to act as nitrate decontamination agents in natural environments. The model clay mineral tested was ferruginous smectite (sample SWa-1) exchanged with either sodium (Na+) or polydiallyldimethylammonium chloride (poly-DADMAC). Structural iron (Fe) in SWa-1 was in either the oxidized or reduced state. Little nitrate uptake was observed in the Na+-SWa-1, which was attributed to coulombic repulsion between the basal surfaces of the smectite and the nitrate anion. The addition of the DADMAC to the SWa-1 reversed the electrostatic charge manifested at the smectite surface from negative to positive, as measured by the zeta (ζ) potential. The positively charged poly-DADMAC-SWa-1 yielded high nitrate uptake due to coulombic attraction in both the oxidized and reduced states of the Fe in the SWa-1. The presence of reduced structural Fe(II) in the positively charged poly-DADMAC-SWa-1 enabled a chemical reduction reaction with the nitrate to produce nitrite. The amounts of nitrite found in solution, however, failed to account for all of the Fe(II) oxidized, so other N reduction products may also have formed or perhaps nitrite was also present in the adsorbed phase. The effects of other complexities, such as polymer configuration at the surface, also need further investigation. The results do clearly establish abiotic nitrate reduction to nitrite and possibly other reduction products. The combination of bacterial activity in soils and sediments, which is known to reduce structural Fe in smectites, and the abundance of organic cations in soil organic matter creates an environment where reversed-charge smectite could exist in nature. This represents a potentially effective system for mitigating harmful effects of nitrate in soils, sediments, groundwater, and surface water.

This systematic review and meta-analysis aimed to investigate the effects of beetroot (BR) or nitrate supplements on body composition indices. A systematic search was conducted for randomised controlled trials (RCT) published up to August 2022 among online databases including Scopus, PubMed/Medline, Web of Science and Embase. Meta-analyses were carried out using a random-effects model. The I2 index was used to assess the heterogeneity of RCT. A total of twelve RCT met the inclusion criteria for this meta-analysis. The pooled effect size of included studies indicated that BR or nitrate supplementation did not change body weight (weighted mean differences (WMD): –0·14 kg, 95 % CI –1·22, 1·51; P = 0·836; I2 = 0 %), BMI (WMD: −0·07 kg/m2, 95 % CI −0·19,0·03; P = 0·174, I2 = 0 %), fat mass (WMD: –0·26 kg, 95 % CI –1·51, 0·98; P = 0·677, I2 = 0 %), waist circumference (WMD: –0·28 cm, 95 % CI –2·30, 1·74; P = 0·786, I2 = 0 %), body fat percentage (WMD: 0·18 %, 95 % CI –0·62, 0·99; P = 0·651, I2 = 0 %), fat-free mass (WMD: 0·31 kg, 95 % CI –0·31, 1·94; P = 0·703, I2 = 0 %) and waist-to-hip ratio (WMD: 0, 95 % CI –0·01, 0·02; P = 0·676, I2 = 0 %). Subgroup analyses based on trial duration, BR or nitrate dose, study design, baseline BMI and athletic status (athlete v. non-athlete) demonstrated similar results. Certainty of evidence across outcomes ranged from low to moderate. This meta-analysis study suggests that BR or nitrate supplements cannot efficiently ameliorate body composition indices regardless of supplement dosage, trial duration and athletic status.

Generally, orchids produce dust-like seeds in which endosperm reduction and embryo undifferentiation represent a derived state shared with species in about 11 other plant families. Orchid seeds are proposed to have a special kind of morphological or morphophysiological dormancy. We test this proposition, overcoming several design limitations of earlier studies, specifically that the in vitro germination method for orchid seeds uses pro-oxidants for disinfection and incorporates nitrate in the medium; both ‘treatments’ might contribute to dormancy breaking, potentially confounding judgement on the depth and nature of the dormant state. Seeds of the tropical orchid Dendrobium cruentum Rchb. f., were sown both in vitro, on a nutrient medium, and ex vitro, on plain agar omitting prior disinfection with sodium hypochlorite. Seeds previously stored and fresh seeds were incubated under combinations of vitro conditions, light treatments, constant or alternating temperatures and nitrate concentration. Seeds of D. cruentum are very small but have a large embryo that occupies most of the seed. Over a range of constant temperature seeds germinated to the spherical protocorm stage just as well ex vitro as in vitro. Neither light nor nitrate were prerequisites for ex vitro germination. The ability of D. cruentum seed to germinate in the absence of environmental or chemical stimuli suggests that mature seed can be non-dormant. Our results support the proposition that neither all DUST seed fit a dormancy class nor all orchids produce morphological or morphophysiological seeds. Finally, embryo/seed volume determinations in orchids may prove as valuable in studies on the evolution and ecology of germination and dormancy as embryo:seed ratios in other angiosperm species.

Beetroot juice (BRJ) has been demonstrated to decrease blood pressure (BP) due to the high inorganic nitrate content. This pilot randomized crossover trial aimed to investigate the effect of two different high nitrate vegetable juices on plasma nitrate concentrations and BP in healthy adults. Eighteen healthy volunteers were randomized to receive 115 ml of BRJ or 250 ml of green leafy vegetable juice for 7 d which contained similar amounts of nitrate (340 mg) daily. Blood samples were collected, and clinic BP measured at baseline and at the end of each juice consumption. Daily home BP assessment was conducted 2 h after juice consumption. Nitrate and nitrite concentrations were analysed using a commercially available kit on a Triturus automated ELISA analyser. Hills and Armitage analysis was used for the two-period crossover design and paired sample t-tests were performed to compare within-group changes. Plasma nitrate and nitrite concentrations significantly increased and there was a significant reduction in clinic and home systolic blood pressure (SBP) mean during the BRJ period (P-values 0⋅004 and 0⋅002, respectively). Home diastolic blood pressure (DBP) reduced significantly during green leafy vegetable juice consumption week (P-value 0⋅03). The difference between groups did not reach statistical significance during the formal crossover analysis adjusted for period effects. BRJ and green leafy vegetable juice may reduce SBP or DBP, but there was no statistically significant difference between the two juices, although this was only a pilot study.

There is increasing evidence for the health benefits of dietary nitrates including lowering blood pressure and enhancing cardiovascular health. Although commensal oral bacteria play an important role in converting dietary nitrate to nitrite, very little is known about the potential role of these bacteria in blood pressure regulation and maintenance of vascular tone. The main purpose of this review is to present the current evidence on the involvement of the oral microbiome in mediating the beneficial effects of dietary nitrate on vascular function and to identify sources of inter-individual differences in bacterial composition. A systematic approach was used to identify the relevant articles published on PubMed and Web of Science in English from January 1950 until September 2019 examining the effects of dietary nitrate on oral microbiome composition and association with blood pressure and vascular tone. To date, only a limited number of studies have been conducted, with nine in human subjects and three in animals focusing mainly on blood pressure. In general, elimination of oral bacteria with use of a chlorhexidine-based antiseptic mouthwash reduced the conversion of nitrate to nitrite and was accompanied in some studies by an increase in blood pressure in normotensive subjects. In conclusion, our findings suggest that oral bacteria may play an important role in mediating the beneficial effects of nitrate-rich foods on blood pressure. Further human intervention studies assessing the potential effects of dietary nitrate on oral bacteria composition and relationship to real-time measures of vascular function are needed, particularly in individuals with hypertension and those at risk of developing CVD.

Information about seed dormancy cycling and germination in relation to temperature and moisture conditions in the natural environment is important for the conservation and restoration of rare species, including Begonia guishanensis and Paraisometrum mileense, two sympatric perennial limestone (karst) species. Dry afterripening (DAR) and wet and dry (WD) cycles at 15/5 and 25/15°C as well as moist chilling (MC) at 15/5°C were used to mimic the natural environment at different times of the year. A field experiment was conducted to monitor seasonal changes in germination responses of the seeds. About 40–65% of B. guishanensis and 5% of P. mileense seeds were dormant at maturity. DAR at 25/15 and 15/5°C as well as MC and WD cycles at 15/5°C alleviated dormancy for B. guishanensis but not P. mileense, and WD cycles at 25/15°C induced a deeper conditional dormancy for both species. Seeds of B. guishanensis exhibited dormancy cycling in the field, with increased dormancy under natural WD cycles at relatively high temperatures during the transition from the dry to the wet season in April to May and decreased dormancy during the wet season from June to October. KNO3 mitigated the dormancy-inducing effect of both artificial and natural WD cycles at relatively high temperatures for B. guishanensis. The field experiment indicated that seeds of B. guishanensis may be able to form a persistent soil seed bank, while almost all seeds of P. mileense germinate at the beginning of the wet season in the field.

To understand better the microbial functional populations which are involved in methanogenesis and denitrification in paddy soils with rice straw (RS) and/or nitrogen fertiliser (potassium nitrate, N) application, the dynamics of methanogens and the denitrifying community were monitored simultaneously during the incubation period. The results show that the community structure of methanogens remained relatively stable among treatments based on 16S rDNA analysis, but fluctuated based on 16S rRNA. The Methanocellaceae and Methanosarcinaceae dominated all treatments at 16S rDNA and 16S rRNA level, respectively. RS+N increased the relative abundance of Methanosaetaceae at the 16S rRNA level, while there was an increasing trend in that Methanomicrobiaceae following RS addition at the 16S rDNA level. RS and/or N did not significantly change the diversity of methanogens targeting both 16S rDNA and 16S rRNA. RS and RS+N increased copy numbers of methanogens targeting both 16S rDNA and 16S rRNA analyses. The community structure and abundance of nirS and nosZ-containing denitrifiers, and the diversity of nirS-containing denitrifiers was significantly altered only by the N treatment. These results indicate that the community structure, diversity and abundance of methanogens respond differently to RS addition at the 16S rDNA and 16S rRNA levels.

Forage maize (Zea mays L.) is often grown year after year on the same land on many intensive dairy farms in north-west Europe. This results in agronomical problems such as weed resistance and decline of soil quality, which may be solved by ley-arable farming. In the current study, forage maize was grown at different nitrogen (N) fertilization levels for 3 years on permanent arable land and on temporary arable land after ploughing out different types of grass–clover swards. Swards differed in management (grazing or cutting) and age (temporary or permanent). Maize yield and soil residual mineral N content were measured after the maize harvest. There was no effect on maize yield of the management of ploughed-out grass–clover swards but a clear effect of the age of grass–clover swards. The N fertilizer replacement value (NFRV) of all ploughed grass–clover swards was >170 kg N/ha in the first year after ploughing. In the third year after ploughing, NFRV of the permanent sward still exceeded 200 kg N/ha, whereas that of the temporary swards decreased to 30 kg N/ha on average. Soil residual nitrate (NO3−) remained below the local, legal threshold of 90 kg NO3− N/ha except for the ploughed-out permanent sward in the third year after ploughing (166 kg NO3− N/ha). The current study highlights the potential of forage maize – ley rotations in saving fertilizer N. This is beneficial both for the environment and for the profitability of dairy production in north-western Europe.

Nitrate promotes seed germination at low concentrations in many plant species, and functions as both a nutrient and a signal. As a nutrient, it is assimilated via nitrite to ammonium, which is then incorporated into amino acids. Nitrate reductase (NR) catalyses the reduction of nitrate to nitrite, the committed step in the assimilation. Seed sensitivity to nitrate is affected by other environmental factors, such as light and after-ripening, and by genotypes. Mode of nitrate action in seed germination has been well documented in Arabidopsis thaliana and the hedge mustard Sisymbrium officinale. In these species nitrate promotes seed germination independent of its assimilation by NR, suggesting that it acts as a signal to stimulate germination. In Arabidopsis, maternally applied nitrate affects the degree of primary dormancy in both wild-type and mutants defective in NR. This indicates that nitrate acts not only during germination, but also during seed development to negatively regulate primary dormancy. Functional genomics studies in Arabidopsis have revealed that nitrate elicits downstream events similar to other germination stimulators, such as after-ripening, light and stratification, suggesting that these distinct environmental signals share the same target(s). In Arabidopsis, the NIN-like protein 8 (NLP8) transcription factor, which acts downstream of nitrate signalling, induces nitrate-dependent gene expression. In particular, a gene encoding the abscisic acid (ABA) catabolic enzyme CYP707A2 is directly regulated by NLP8. This regulation triggers a nitrate-induced ABA decrease that permits seed germination. This review article summarizes an update of our current understanding of the regulation of seed dormancy and germination by nitrate.

This research note discusses the accuracy of the main sources used to study the foreign sector during the export-led growth process in Chile. Chilean foreign trade statistics are available for the period under analysis (1850-1930) and offered a good overview of products exported and imported. Bilateral trade data are also available providing information of exports and imports by origin and destiny. Although more research is needed on trade prices, we conclude that Chilean statistics are reliable and provide a way for understanding the export-led growth in Chile and the trade performance of the Chilean partners.

Incorporation of cover crop residue into the soil has been suggested as a means for reducing weed seedbanks. To explore this hypothesis, we buried mesh bags of seeds mixed with sand at 15-cm depth in late fall in plots that had been planted with rye (Secale cereale L.) or hairy vetch (Vicia villosa Roth.) or left unplanted. Separate bags contained either velvetleaf (Abutilon theophrasti Medik.), giant foxtail (Setaria faberi Herrm.), Powell amaranth (Amaranthus powellii S. Watson), or common lambsquarters (Chenopodium album L.). The experiment used a randomized complete block design with five replications, and enough bags were buried to allow a final recovery in each of the following three springs. Each spring, bags were exhumed, and seeds were either counted and tested for viability or mixed with chopped cover crop material or simply stirred for control bags, and the material was reburied. The experiment was completed twice with initial burials in fall of 2011 and 2013. Rye had no consistent effect on persistence of seeds of any of the species. For two observation intervals, rye increased persistence of a species; for another two intervals, it decreased persistence relative to the control; but mostly rye did not affect persistence. Hairy vetch decreased persistence of C. album and A. powellii in both runs of the experiment but had no effect on persistence of A. theophrasti and S. faberi. Germination of the first two species is promoted by nitrate, whereas A. theophrasti germination is not sensitive to nitrate, and S. faberi is only rarely nitrate sensitive. We suggest that nitrate released during decomposition of hairy vetch may have promoted fatal germination of C. album and A. powellii. Incorporation of legume cover crops like hairy vetch may provide a means for decreasing the seedbanks of the many weed species whose germination is promoted by nitrate. The lack of any reduction of A. theophrasti and S. faberi seed persistence in response to hairy vetch and the inconsistent and mostly negligible effect of rye indicate that a general increase in readily decomposable organic matter through incorporation of cover crops may be ineffective at reducing weed seedbanks.

Adding nitrate to or increasing the concentration of lipid in the diet are established strategies for reducing enteric methane (CH4) emissions, but their effectiveness when used in combination has been largely unexplored. This study investigated the effect of dietary nitrate and increased lipid included alone or together on CH4 emissions and performance traits of finishing beef cattle. The experiment was a 2×4 factorial design comprising two breeds (cross-bred Aberdeen Angus (AAx) and cross-bred Limousin (LIMx) steers) and four dietary treatments (each based on 550 g forage : 450 g concentrate/kg dry matter (DM)). The four dietary treatments were assigned according to a 2×2 factorial design where the control treatment contained rapeseed meal as the main protein source, which was replaced either with nitrate (21.5 g nitrate/kg DM); maize distillers dark grains (MDDG, which increased diet ether extract from 24 to 37 g/kg DM) or both nitrate and MDDG. Steers (n=20/dietary treatment) were allocated to each of the four treatments in equal numbers of each breed with feed offered ad libitum. After 28 days adaptation to dietary treatments, individual animal intake, performance and feed efficiency were recorded for 56 days. Thereafter, CH4 emissions were measured over 13 weeks (six steers/week). Increasing dietary lipid did not adversely affect animal performance and showed no interactions with dietary nitrate. In contrast, addition of nitrate to diets resulted in poorer live-weight gain (P<0.01) and increased feed conversion ratio (P<0.05) compared with diets not containing nitrate. Daily CH4 output was lower (P<0.001) on nitrate-containing diets but increasing dietary lipid resulted in only a non-significant reduction in CH4. There were no interactions associated with CH4 emissions between dietary nitrate and lipid. Cross-bred Aberdeen Angus steers achieved greater live-weight gains (P<0.01), but had greater DM intakes (P<0.001), greater fat depth (P<0.01) and poorer residual feed intakes (P<0.01) than LIMx steers. Cross-bred Aberdeen Angus steers had higher daily CH4 outputs (P<0.001) but emitted less CH4 per kilogram DM intake than LIMx steers (P<0.05). In conclusion, inclusion of nitrate reduced CH4 emissions in growing beef cattle although the efficacy of nitrate was less than in previous work. When increased dietary lipid and nitrate inclusion were combined there was no evidence of an interaction between treatments and therefore combining different nutritional treatments to mitigate CH4 emissions could be a useful means of achieving reductions in CH4 while minimising any adverse effects.

Germination responses of redroot pigweed (Amaranthus retroflexus L.) seeds to temperature, water potential, atmospheric ethylene and carbon dioxide concentrations, light, and nitrate ion were examined individually. Seeds kept in dry storage at −20 C and tested within 2 yr of harvest germinated at 35 C (12 to 25%) or 39.5 C (40 to 65%), but only 0 to 2% at 30 C and below. Germination at 35 C was prevented by water potentials below −4 bars. When seeds were kept in dry storage at 24 to 28 C, afterripening became evident within 2 months. After storage at this temperature for 4 yr, seeds showed 38% germination at 14 C, 40% at 35 C and −8 bars water potential, and over 90% under more favorable conditions. Ethylene (1 to 100 ppmv) or continuous light enhanced germination at 30 C regardless of degrees of afterripening, although the ethylene effect was most dramatic in nonafterripened seeds. Ethylene at 100 ppmv caused 40% germination in these seeds, compared to 1% for controls. Neither carbon dioxide (0.001 to 4.5% v/v) nor dissolved potassium nitrate (0.02 to 0.2% w/v) influenced germination. These results are discussed in relation to environmental factors influencing field emergence of redroot pigweed.

The herbicide dichlobenil (2,6-dichlorobenzonitrile) inhibited soil nitrification significantly at 100 ppm following 1 and 2 weeks incubation but did not inhibit nitrification at the rates recommended for weed control.