Characterization of endophytic bacteriome diversity and associated beneficial bacteria inhabiting a macrophyte Eichhornia crassipes

Introduction

The endosphere of a plant is an interface containing a thriving community of endobacteria that can affect plant growth and potential for bioremediation. Eichhornia crassipes is an aquatic macrophyte, adapted to estuarine and freshwater ecosystems, which harbors a diverse bacterial community. Despite this, we currently lack a predictive understanding of how E. crassipes taxonomically structure the endobacterial community assemblies across distinct habitats (root, stem, and leaf).

Methods

In the present study, we assessed the endophytic bacteriome from different compartments using 16S rRNA gene sequencing analysis and verified the in vitro plant beneficial potential of isolated bacterial endophytes of E. crassipes.

Results and discussion

Plant compartments displayed a significant impact on the endobacterial community structures. Stem and leaf tissues were more selective, and the community exhibited a lower richness and diversity than root tissue. The taxonomic analysis of operational taxonomic units (OTUs) showed that the major phyla belonged to Proteobacteria and Actinobacteriota (> 80% in total). The most abundant genera in the sampled endosphere was Delftia in both stem and leaf samples. Members of the family Rhizobiaceae, such as in both stem and leaf samples. Members of the family Rhizobiaceae, such as Allorhizobium- Neorhizobium-Pararhizobium-Rhizobium were mainly associated with leaf tissue, whereas the genera Nannocystis and Nitrospira from the families Nannocystaceae and Nitrospiraceae, respectively, were statistically significantly associated with root tissue. Piscinibacter and Steroidobacter were putative keystone taxa of stem tissue. Most of the endophytic bacteria isolated from E. crassipes showed in vitro plant beneficial effects known to stimulate plant growth and induce plant resistance to stresses. This study provides new insights into the distribution and interaction of endobacteria across different compartments of E. crassipes Future study of endobacterial communities, using both culture-dependent and -independent techniques, will explore the mechanisms underlying the wide-spread adaptability of E. crassipesto various ecosystems and contribute to the development of efficient bacterial consortia for bioremediation and plant growth promotion.

Sub-optimal nutrient regime coupled with Bacillus and Pseudomonas sp. inoculation influences trichome density and cannabinoid profiles in drug-type Cannabis sativa

Cannabis sativa remains under heavy legal restriction around the globe that prevents extensive investigations into agricultural applications for improving its development. This work investigates the potential of specific plant growth-promoting rhizobacteria (PGPR) to improve Cannabis cannabinoid yield through increased trichome densities on floral organs, and to determine if sub-optimal environmental conditions would affect the outcomes of PGPR presence by altering plant development and cannabinoid profiles. Here, Pseudomonas sp. or Bacillus sp. were applied to the root system either separately or in a consortium to determine the effect of this bacterial treatment on the density of stalked glandular trichomes. Further, a low nutrient regime was applied for the first half of plant development to determine if an environmental stressor interacts with the effects of the microbial treatments on stalked trichome densities. Following 8 weeks of flower development, trichome density on calyces and bracts of inflorescences were determined using microscopy. Our findings unexpectedly indicate that recommended nutrient levels were linked to a decreasing trend in trichome densities with PGPR inoculations, but a low nutrient regime coupled with PGPR treatment increased them. Cannabinoid content is partially consistent with these results, in that a low nutrient regime increased the abundance of key cannabinoids compared to recommended regimes, with Bacillus sp. inoculation linked to the greatest number of significant changes between the two nutrient regimes. Overall, this work provides insight into how PGPR presence affects Cannabis stalked trichome development and cannabinoid profiles, and how environmental stressors can affect, and even enhance, trichome densities and influence major cannabinoid production, thereby pointing towards avenues for reducing the reliance on synthetic fertilizers during plant production without compromising yield.

A Single Intranasal Dose of Bacterial Therapeutics to Calves Confers Longitudinal Modulation of the Nasopharyngeal Microbiota: a Pilot Study

Bovine respiratory disease (BRD) remains the most significant health challenge affecting the North American beef cattle industry and results in $3 billion in economic losses yearly. Current BRD control strategies mainly rely on antibiotics, with metaphylaxis commonly employed to mitigate BRD incidence in commercial feedlots.

Aragonite toothpaste for management of dental calculus: A double-blinded randomized controlled clinical trial

Objectives

Aragonite from animal origin such as cuttlefish bone powder is an abrasive with hardness properties ideal for calculus removal. The purpose of this randomized controlled trial was to test the efficacy of a cuttlebone‐derived aragonite toothpaste in removing dental calculus.

Materials and Methods

Eighty‐one patients who fulfilled the inclusion criteria were blindly and randomly assigned into two study groups. The intervention treatment group (n = 40) received cuttlebone toothpaste (Dr. D‐Tart) and the control group (n = 41) received an off‐the‐shelf commercial toothpaste (Crest). Evaluations were performed before and after scaling and polishing procedures done at 3 months in order to evaluate the toothpaste's ability to remove calculus and to prevent calculus formation. Calculus, stains, plaque, and gingival indices scores, and patient satisfaction surveys were compared at baseline (first visit), 3, and 9 months, using generalized linear models and Wald's χ² test.

Results

At the end of the 3‐month period, the intervention group showed a 30% reduction in total calculus compared to the baseline score (p = .0006) and 45% less total calculus compared to the control group (p = .0001). Six months after scaling, the mean calculus score for Crest users was 42% higher than that for Dr. D‐Tart users (p = .0692). There was a significant improvement in the gingival health of cuttlebone toothpaste users at the observed intervals, and both kinds of toothpaste achieved comparable results in terms of plaque and stains removal.

Conclusions

Aragonite toothpaste can remove calculus, prevent calculus formation, and improve gingival health. Patients are generally satisfied with the performance of the aragonite toothpaste. Clinical significance: Animal‐derived aragonite toothpaste (Dr. D‐Tart) shows promising efficacy in removing calculus, preventing calculus formation, and for the improvement of gingival health. Clinical trial ID: A08‐M35‐16B.

Marginal quality water arbitrated essential oil contents in metal hoarded flower petals of scented roses

Climate change and the consequent alteration in agricultural circumstances enhance the susceptibility of fresh water use particularly in water-scarce regions. Marginal quality water reuse is a common alternative practice but possible perils of metal accretion in plant parts are mostly ignored. The present research aimed to probe the impact of treated wastewater (TWW) and untreated wastewater (UTWW) on metal accumulation in flower petals and their influence on essential oil contents of fragrant Rosa species (R. Gruss-an-teplitz, R. bourboniana, R. centifolia, R. damascena) in a peri-urban area of Faisalabad, Pakistan during January, 2017 to December, 2018. The mineral and chemical contents in canal water (CW) and TWW were less than recommended levels of national environmental quality standards (NEQS) for wastewater of Pakistan. The experimentally UTWW possessed higher electrical conductivity (EC), biological and chemical oxygen demand (BOD and COD), and some metals (Pb, Co, Cr) that were above the permissible levels. The experimental data revealed that except Cr other metals contents in the flower petals were less than the WHO recommended limits (for medicinal plants) under experimental irrigation regimes. Rosa centifolia and R. damascena possessed higher metal i.e. Zn, Cu, Pb, Cr, Co contents while Fe and Ni contents were higher in R. Gruss-an-Teplitz and R. bourboniana respectively. There were twelve constituents which were detected in essential oil by gas chromatography. Major constituents were phenyl ethyl alcohol, citronellol, geranyl acetate, γ- undelactone, methyl eugenol, and limonene whose share was 48.17%, 41.11%, 8.46%, 4.82%, 4.44%, and 4.15% respectively whereas concentrations of other 06 constituents were less than 3.7%. Phenyl ethyl alcohol, lion shared constituent of essential oil was found highest (48.17%) in R. Gruss-an-Teplitz whereas minimum level was recorded in R. damascena (28.84%) under CW. In contrast, citronellol (chief component of fragrance) was highest in R. damascena (41.11%) in UTWW while the lowest level was found in R. Gruss-an-Teplitz (17.41%) in CW. This study confirmed the variations in metal concentrations of Rosa species due to different absorbability of each metal in flower petals. It also indicates that wastewater did not affect the composition but there were quantitative differences in aroma constituents and chemical composition of essential oil.

Identification of Differential Drought Response Mechanisms in Medicago sativa subsp. sativa and falcata through Comparative Assessments at the Physiological, Biochemical, and Transcriptional Levels

Alfalfa (Medicago sativa L.) is an extensively grown perennial forage legume, and although it is relatively drought tolerant, it consumes high amounts of water and depends upon irrigation in many regions. Given the progressive decline in water available for irrigation, as well as an escalation in climate change-related droughts, there is a critical need to develop alfalfa cultivars with improved drought resilience. M. sativa subsp. falcata is a close relative of the predominantly cultivated M. sativa subsp. sativa, and certain accessions have been demonstrated to exhibit superior performance under drought. As such, we endeavoured to carry out comparative physiological, biochemical, and transcriptomic evaluations of an as of yet unstudied drought-tolerant M. sativa subsp. falcata accession (PI 641381) and a relatively drought-susceptible M. sativa subsp. sativa cultivar (Beaver) to increase our understanding of the molecular mechanisms behind the enhanced ability of falcata to withstand water deficiency. Our findings indicate that unlike the small number of falcata genotypes assessed previously, falcata PI 641381 may exploit smaller, thicker leaves, as well as an increase in the baseline transcriptional levels of genes encoding particular transcription factors, protective proteins, and enzymes involved in the biosynthesis of stress-related compounds. These findings imply that different falcata accessions/genotypes may employ distinct drought response mechanisms, and the study provides a suite of candidate genes to facilitate the breeding of alfalfa with enhanced drought resilience in the future.

Missing and unerupted teeth in osteogenesis imperfecta

INTRODUCTION

Osteogenesis imperfecta (OI) is a genetic disorder characterized by bone fragility and craniofacial and dental abnormalities such as congenitally missing teeth and teeth that failed to erupt which are believed to be doubled in OI patients than normal populations and were associated with low oral health quality of life. However, the etiology of these abnormalities remains unclear. To understand the factors influencing missing and unerupted teeth, we investigated their prevalence in a cohort of OI patients as a function of the clinical phenotype (OI type), the genetic variant type, the tooth type and the onset of bisphosphonate treatment.

METHOD

A total of 144 OI patients were recruited from The Shriners Hospital, Montreal, Canada, between 2016 and 2017. Patients were evaluated using intraoral photographs and panoramic radiographs. Missing teeth were evaluated in all patients, and unerupted teeth were assessed only in patients ≥15 years old (n = 82).

RESULTS

On average, each OI patient had 2.4 missing teeth and 0.8 unerupted teeth, and the most common missing and unerupted teeth were the premolars and the upper second molars, respectively. These phenomena were more prominent in OI type III and IV than in OI type I, and were not sex or age-related. Missing teeth were significantly more common in patients with C-propeptide variants than all other variants (p-value <0.05). Unerupted teeth were significantly more common in patients with α1 and α2 glycine variants or substitutions than in those with haploinsufficiency variants. Early-onset of bisphosphonate treatment would significantly increase the risk of unerupted teeth in patients with OI types III and IV (OR = 1.68, 95% CI (1.15-1.53)).

CONCLUSION

The prevalence of missing and unerupted teeth at the tooth type level in OI patients varies according to the nature of the collagen variants and the OI type. These findings highlight the role of collagen in tooth development and eruption.

Osteogenesis imperfecta tooth level phenotype analysis: Cross-sectional study

INTRODUCTION

Dental anomalies in Osteogenesis imperfecta (OI), such as tooth discoloration, pulp obliteration (calcified dental pulp space), and taurodontism (enlarged dental pulp space) vary between and within patients. To better understand the associations and variations in these anomalies, a cross-sectional study was designed to analyze the dental phenotype in OI patients at the individual tooth type.

METHOD

A cohort of 171 individuals with OI type I, III and IV, aged 3-55 years, were recruited and evaluated for tooth discoloration, pulp obliteration, and taurodontism at the individual tooth level, using intraoral photographs and panoramic radiographs.

RESULTS

Genetic variants were identified in 154 of the participants. Patients with Helical α1 and α2 glycine substitutions presented the highest prevalence of tooth discoloration, while those with α1 Haploinsufficiency had the lowest (<10%). C-propeptide variants did not cause discoloration but resulted in the highest pulp obliteration prevalence (~%20). The prevalence of tooth discoloration and pulp obliteration was higher in OI types III and IV and increased with age. Tooth discoloration was mainly observed in teeth known to have thinner enamel (i.e. lower anterior), while pulp obliteration was most prevalent in the first molars. A significant association was observed between pulp obliteration and tooth discoloration, and both were associated with a lack of occlusal contact. Taurodontism was only found in permanent teeth and affected mostly first molars, and its prevalence decreased with age.

CONCLUSION

The dental phenotype evaluation at the tooth level revealed that different genetic variants and associated clinical phenotypes affect each tooth type differently, and genetic variants are better predictors of the dental phenotype than the type of OI. Our results also suggest that tooth discoloration is most likely an optical phenomenon inversely proportional to enamel thickness, and highly associated with pulp obliteration. In turn, pulp obliteration is proportional to patient age, it is associated with malocclusion and likely related to immature progressive dentin deposition. Taurodontism is an isolated phenomenon that is probably associated with delayed pulpal maturation.

5 Effect of rest stop on welfare indicators of conditioned and non-conditioned ranch-direct or auction-market-sourced beef cattle, transported by road

The aim of this study was to assess the effect of an 8h rest stop after 36 h of road transport on physiological and behavioral indicators of welfare in 7–8-mo-old conditioned and non-conditioned beef calves, sourced from either a ranch or an auction market. Three hundred and twenty weaned calves (245 ± 35.7 kg BW) were randomly assigned to a 2 × 2 × 2 factorial design: conditioning, conditioned (C) or non-conditioned (N); source, ranch direct (R) or auction market (A); and rest, 0 (R0) or 8 (R8) h. After resting, animals were transported for an additional 4 h. A subset of 12 animals/treatment were sampled for non-esterified fatty acids (NEFA), serum amyloid-A (SAA) and creatine kinase (CK) concentrations prior to the first loading (L1); after 36 h of transport; prior to and after the additional 4 h of transport, on the day of arrival (0); and 1, 2, 3, 5, 14, and 28 d after the 4h transport. Daily standing % and dry matter intake (DMI) were assessed for 3 d after transport. Data were analyzed using the GLIMMIX procedure of SAS. Fixed effects included conditioning, source, and time (nested in rest), while random effects were animal and pen. At L1, mean concentrations of NEFA, SAA and CK were greater (P &lt; 0.05) for N-R0 than C-R0 and for N-R8 than C-R8. The N and R groups had greater (P &lt; 0.05) standing % than the C and A groups, respectively. On d 0 and 1, the C-R0 and C-R8 groups had greater (P &lt; 0.05) DMI than the N-R0 and N-R8 groups, respectively. Overall, physiological and behavioral indicators of welfare were greater in conditioned than non-conditioned calves, while fewer differences were observed between ranch and auction market calves, as well as rested or unrested calves.

Intranasal Bacterial Therapeutics Reduce Colonization by the Respiratory Pathogen Mannheimia haemolytica in Dairy Calves

Six Lactobacillus strains originating from the nasopharyngeal microbiota of cattle were previously characterized in vitro and identified as candidate bacterial therapeutics (BTs) for mitigating the bovine respiratory pathogen Mannheimia haemolytica In the present study, these BT strains were evaluated for their potential to (i) reduce nasal colonization by M. haemolytica, (ii) modulate the nasal microbiota, and (iii) stimulate an immune response in calves experimentally challenged with M. haemolytica. Twenty-four Holstein bull calves (1 to 3 weeks old) received either an intranasal BT cocktail containing 6 Lactobacillus strains (3 × 109 CFU per strain; BT + Mh group) 24 h prior to intranasal M. haemolytica challenge (3 × 108 CFU) or no BTs prior to challenge (Mh, control group). Nasal swab, blood, and transtracheal aspiration samples were collected over the course of 16 days after BT inoculation. Counts of M. haemolytica were determined by culturing, and the nasal and tracheal microbiotas were evaluated using 16S rRNA gene sequencing. Serum cytokines (interleukin-6 [IL-6], IL-8, and IL-10) were quantified by enzyme-linked immunosorbent assay (ELISA). Administration of BT reduced nasal colonization by M. haemolytica (P = 0.02), modified the composition and diversity of the nasal microbiota, and altered interbacterial relationships among the 10 most relatively abundant genera. The BT + Mh calves also had a lower relative abundance of Mannheimia in the trachea (P < 0.01) but similar cytokine levels as Mh calves. This study demonstrated that intranasal BTs developed from the bovine nasopharyngeal Lactobacillus spp. were effective in reducing nasal colonization by M. haemolytica in dairy calves.IMPORTANCE Bovine respiratory disease (BRD) is one of the significant challenges for the modern dairy industry in North America, accounting for 23 to 47% of the total mortality among pre- and postweaned dairy heifers. Mass medication with antibiotics is a common practice to control BRD in dairy cattle. However, the emergence of multidrug-resistant BRD pathogens highlights the importance of developing alternatives to antibiotics for BRD mitigation. Using a targeted approach, we recently identified 6 Lactobacillus strains originating from the bovine respiratory microbiota as candidates to be used as bacterial therapeutics (BTs) for the mitigation of the BRD pathogen Mannheimia haemolytica Here, we demonstrated that intranasal inoculation of the BT strains reduced nasal colonization by M. haemolytica in dairy calves experimentally challenged with this pathogen. This study, for the first time, shows the potential use of intranasal BTs as an alternative to mitigate BRD pathogens in cattle.

PSIII-14 Infrared thermography as a tool to detect inflammation in feedlot lambs with footrot

Infrared thermography (IRT) has been used as a non-invasive tool to detect inflammatory processes associated with disease in livestock. The aim of this study was to evaluate IRT as a tool to compare healthy and footrot (FR) affected hooves in feedlot lambs with varying degrees of lameness over two seasons. A total of 106 lame lambs with footrot from a feedlot in Alberta were individually categorized according to a 3-point locomotion scale [1 = mild (n = 7), 2 = moderate (n = 46) and 3 = severe lameness (n = 53)] during the summer (n = 39) and fall (n = 68) of 2018. All lambs were physically examined once by two experienced observers to determine if the lamb had footrot. IRT images of the interdigital space were used to obtain the maximum hoof temperature (MHT) of both FR affected as well as healthy (CT) hooves within the same animal. Generalized linear mixed models (SAS PROC GLIMMIX) were performed separately for each season and diagnosis and included locomotion score as a fixed effect and ambient temperature as a co-variate. Predicted means were compared using the limits at 95% of confidence. Overall, greater MHT (P &lt; 0.05) were observed for FR affected compared to unaffected hooves for lambs categorized as moderately and severely lame, within each season. However, no differences (P &gt; 0.05) in MHT were observed for lambs categorized as mildly lame, likely due to the small number of lambs having a locomotion score of 1. Under the conditions of this study, thermal images can be effectively used as a tool to distinguish footrot affected hooves in feedlot lambs with moderate and severe lameness. Further studies should be conducted with more lambs with a locomotion score of 1 to assess the relationship between mild lameness, IRT, and footrot diagnosis.

313 Effects of transport time and rest stop duration on welfare indicators of beef cattle travelling by road

Forthcoming revisions to Canadian Transport regulations indicate un-weaned and weaned calves can be transported a maximum of 12 and 36 h, respectively, before an 8 h rest is required. The aim of this study was to assess the effect of rest duration after 12 and 36 h of transport on physiological and behavioral indicators of welfare in 7–8 mo old beef calves. Three hundred and twenty weaned calves (258 ± 23.9 kg BW) were randomly assigned to a 2 × 4 factorial design: 12 and 36 h of transport; and 0 (R0), 4 (R4), 8 (R8), and 12 (R12) h of rest. After the resting period animals were transported for an additional 4 h. A subset of 12 animals/treatment were sampled for non-esterified fatty acids (NEFA), haptoglobin and lactate concentrations prior to, and after the first and the 4 h transport, and 7 h, 2 and 28 d after the 4 h transport. Standing and lying behavior was assessed for 14 d after transport. Data was analyzed using the GLIMMIX procedure of SAS, where transport, and time nested within rest period were fixed effects and animal was a random effect. NEFA concentrations were greater (P &lt; 0.01) in 12-R4 than 12-R8 and 12-R12 calves, while 36-R0 calves had greater (P ≤ 0.05) NEFA concentrations than 36-R4, 36-R8 and 36-R12 calves after the 4 h transport. Haptoglobin concentrations were greater (P &lt; 0.01) in 36 than 12 h calves. No differences (P &gt; 0.10) were observed for lactate. The day after transport, 36-R8 calves spent more (P &lt; 0.01) time lying than 12-R8 calves. Overall, physiological indicators were greater in calves transported for 36 than 12 h, while no differences were observed between rest stops with the exception of NEFA, where overall concentrations were greater after shorter than longer rest periods.

Evaluation of the Nasopharyngeal Microbiota in Beef Cattle Transported to a Feedlot, With a Focus on Lactic Acid-Producing Bacteria

The nasopharyngeal (NP) microbiota is important in defining respiratory health in feedlot cattle, with certain NP commensals potentially protecting against bovine respiratory disease (BRD) pathogens. In the present study, we evaluated longitudinal changes in the NP microbiota with a focus on lactic acid-producing bacteria (LAB) and their linkage with BRD-associated bacteria in steers (n = 13) that were first transported to an auction market, and then to a feedlot. Deep nasopharyngeal swabs were collected at the farm before transportation to the auction market (day 0), at feedlot placement (day 2), and 5 (day 7) and 12 (day 14) days after feedlot placement. Swabs were processed for the assessment of the NP microbiota using 16S rRNA gene sequencing, and for the detection of Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni by culturing. Possible associations among the top 15 most relatively abundant bacterial genera were predicted using a stepwise-selected generalized linear mixed model. Correlations between LAB and BRD-associated Pasteurellaceae families were also assessed. In addition, antimicrobial activity of selected LAB isolates against M. haemolytica was evaluated in vitro. A noticeable shift was observed in the NP microbial community structure, and in the relative abundance of LAB families as a result of auction market exposure, transport and feedlot placement. Varying degrees of positive or negative associations between the 15 most relatively abundant genera were observed. Many of the LAB families were inversely correlated with the BRD-associated Pasteurellaceae family as the cattle were transported to the auction market and then to the feedlot. Nearly all steers were culture-negative for M. haemolytica and H. somni, and P. multocida became less prevalent after feedlot placement. Isolates from the Lactobacillaceae, Streptococcaceae, and Enterococcaceae families inhibited the growth of M. haemolytica. The results of this study indicated that the NP microbiota became more diverse with an increase in microbial richness following transport to an auction market and feedlot. This study provides evidence of potential cooperation and exclusion taking place in the respiratory microbial community of cattle which may be useful for developing microbial-based strategies to mitigate BRD.

Experiences of Food Insecurity Modeled by Redundancy Analysis: A Cross-sectional Study of Uganda, 2014–2017 (P04-034-19)

Objectives

Food insecurity (FI) is one of the leading health and nutrition issues in Uganda, where it affects 30% of the population of the country. It negatively impacts physical, mental, and social health that in turn affect nutritional requirements. The purpose of this study was therefore to (1) determine the prevalence of FI in Uganda from 2014 to 2017 (2) assess whether or not the linear additive combination of socio-economic and demographic factors affect FI in Uganda in the studied years; and (3) assess the association between FI and Physical Health Index (PHI).

Methods

We used Gallup World Poll data for Uganda from 2014 to 2017, 4000 respondents ( >15 yr). FI was assessed in eight binary response items measured according to the Food Insecurity Experience Scale (FIES) (Voices of Hungry project, Food and Agriculture Organization of the United Nations). For redundancy analyses (RDA), the rda function (vegan package in R) was used. Path analysis was used to investigate assumptions regarding recursivity and directions of causal relationships.

Results

The linear combination of socioeconomic and demographic factors explained on average 18% of the variance in the items of the FIES. Nevertheless, permutation tests indicated the high level of statistical significance of the RDA models (all P = .0001, the lowest possible value after 999 permutations). Linear regression indicated that the raw FIES score increased by approximately .5 per year. High levels of the PHI were associated with low levels of FI. Furthermore, low levels of PHI were correlated with increased business corruption in 2016 and 2017. Heterogeneous associations between business corruption and levels of FI was found over the four years of the study. Unemployment, low education levels, low income, being single, and living in a larger household and in a large city were positively associated with FI. As expected, household size was negatively correlated with income in 2014, 2016, and 2017.

Conclusions

The results indicated that the studied factors of FI explained a statistically significant portion of the variance in experiences of FI in Uganda in the years of the study. Further structural equation modeling (path modeling) will be necessary for the evaluation and proposals of policies and programs related to food security, health, and nutrition in Uganda.

Funding Sources

None.

Supporting Tables, Images and/or Graphs

Closing the Yield Gap for Cannabis: A Meta-Analysis of Factors Determining Cannabis Yield

Until recently, the commercial production of Cannabis sativa was restricted to varieties that yielded high-quality fiber while producing low levels of the psychoactive cannabinoid tetrahydrocannabinol (THC). In the last few years, a number of jurisdictions have legalized the production of medical and/or recreational cannabis with higher levels of THC, and other jurisdictions seem poised to follow suit. Consequently, demand for industrial-scale production of high yield cannabis with consistent cannabinoid profiles is expected to increase. In this paper we highlight that currently, projected annual production of cannabis is based largely on facility size, not yield per square meter. This meta-analysis of cannabis yields reported in scientific literature aimed to identify the main factors contributing to cannabis yield per plant, per square meter, and per W of lighting electricity. In line with previous research we found that variety, plant density, light intensity and fertilization influence cannabis yield and cannabinoid content; we also identified pot size, light type and duration of the flowering period as predictors of yield and THC accumulation. We provide insight into the critical role of light intensity, quality, and photoperiod in determining cannabis yields, with particular focus on the potential for light-emitting diodes (LEDs) to improve growth and reduce energy requirements. We propose that the vast amount of genomics data currently available for cannabis can be used to better understand the effect of genotype on yield. Finally, we describe diversification that is likely to emerge in cannabis growing systems and examine the potential role of plant-growth promoting rhizobacteria (PGPR) for growth promotion, regulation of cannabinoid biosynthesis, and biocontrol.

Getting to the root of the matter: Water-soluble and volatile components in thermally-treated biosolids and biochar differentially regulate maize (Zea mays) seedling growth

The use of thermally treated biomass, including biochar, as soil amendments can improve soil fertility by providing nutrients, stable C and improving soil water-holding capacity. However, if the degree of carbonization is low, these soil amendments can lower crop productivity as a result of high salinity or organic compounds. The overall effect of these soil amendments is mediated by complex relationships between production conditions, soil properties and environmental conditions. This study aimed to 1) characterize the physiochemical properties and organic compounds released by three soil amendments (softwood biochar or pyrogenic carbonaceous biosolids), 2) determine the effects of these amendments on maize (Zea mays) seedling productivity, and 3) relate properties of these amendments to effects on maize seedling productivity under controlled environment conditions. Physicochemical properties and mobile organic compounds (water-soluble and volatile organic compounds were determined. The amendments were tested in maize germination and greenhouse experiments. Chemical fingerprinting of volatile and water-soluble compounds revealed over 100 mobile organic species. Increasing treatment temperature from 270 to 320°C reduces phytotoxicity of pyrogenic carbonaceous biosolids soil amendments. Water-soluble components of pyrogenic carbonaceous biosolids produced at 270°C (inorganic N, Na and/or organic compounds) were associated with reduced maize seedling productivity. Volatile components of pyrogenic carbonaceous biosolids produced at 320°C were associated with improved maize seedling productivity; nitrogen uptake was increased in spite of smaller root systems as a result of increased mineralization of soil or amendment N and/or uptake of organic N compounds. These results suggest that pyrogenic carbonaceous biosolids have potential benefits to provide plant nutrients when the amount of organic and inorganic species are limited during early growth stages, under greenhouse conditions. Future studies should examine these effects under field conditions to confirm whether controlled environment results translate into effects on yield.

Heavy metal accumulation imparts structural differences in fragrant Rosa species irrigated with marginal quality water

Wastewater is an alternative to traditional sources of renewable irrigation water in agriculture, particularly in water-scarce regions. However, the possible risks due to heavy metals accumulation in plant tissues are often overlooked by producers. The present study aimed to identify heavy metals-induced structural modifications to roots of scented Rosa species that were irrigated with water of marginal quality. The chemical and mineral contents from the experimental irrigation canal water (control) and treated wastewater were below the limits recommended by the Pakistan Environmental Protection Agency (Pak-EPA) for medicinal plants. The experimentally untreated wastewater contained electrical conductivity (EC), chemical oxygen demand (COD), biological oxygen demand (BOD), and heavy metals (Co, Cu, Cd, Pb) that were above the recommended limits. The responses by wastewater-treated Rosa species (Rosa damascena, R. bourboniana, R. Gruss-an-Teplitz, and R. centifolia) were evaluated. The experimental data revealed that treated wastewater significantly increased the thickness of collenchyma (cortex and pith) and parenchyma tissues (vascular bundle, xylem, and phloem) of R. Gruss-an-Teplitz. Root dermal tissues (epidermis) of R. bourboniana also responded to treated wastewater. R. damascena and R. centifolia were the least affected species, under the experimental irrigation conditions. Collenchyma and dermal tissues were thicker in R. damascena and R. Gruss-an-Teplitz under untreated wastewater conditions. In parenchyma tissues, vascular bundles were thicker in R. damascena in untreated wastewater conditions, while the xylem and phloem of R. Gruss-an-Teplitz were thicker where treated wastewater was applied. In tissues other than the vascular bundle, the differences in anatomical metrics due to the experimental irrigation treatments were greater during the second year of the experiment than in the first year. The contents of metals other than chromium in the roots and stems of roses were below the WHO limits, under all of the experimental irrigation conditions. Rosa centifolia contained higher heavy metals content than the other experimental species, and heavy metals content was associated with anatomical changes due to the treatments. We conclude that, under conditions of wastewater irrigation, R. Gruss-an-Teplitz was highly resistant; R. damascena was moderately resistant while R. bourboniana and R. centifolia were the most susceptible to irrigation with marginal quality water. This is the first report of plant tissue responses to wastewater irrigation by the experimental species. Regarding the accumulation of heavy metals in rose plant tissues, the results confirm that untreated wastewater must be treated to grow Rosa species where water is scarce.

A micromolar concentration of lipo-chitooligosaccharide (Nod Bj V [C18:1, MeFuc]) regulates the emergence and seed productivity of rapid cycling canola (Brassica napus [L.]) plants

The objective of this experiment was to assess whether or not the application of lipo-chitooligosaccharide (Nod Bj V [C18:1, MeFuc]) (LCO) would increase yield factors under conditions that would inhibit canola (Brassica napus L.) productivity. The seed application reduced the percentage of plants that were unproductive by 15.10% compared to plants grown from untreated seeds. Based on the 95% confidence interval for the difference, untreated plants would produce 38 to 3% fewer seeds than plants grown from LCO treated seeds. The experimental conditions were artificial, but further experimentation, with agricultural cultivars grown in greenhouses where natural conditions were simulated, confirmed that LCO treatment can contribute to canola yield.