Inoculation Treatments Research Articles

Increased Resilience of Peas Toward Root Rot Pathogens Can Be Predicted by the Nematode Metabolic Footprint

Legumes are important drivers of soil fertility, however, their frequent use in rotations fosters long-lived soil-borne pathogens that can seriously compromise legume root health and nitrogen fixation. To overcome this, the current study aims at improving the general soil suppressiveness toward pests and diseases by agroecosystem management that can be predicted by nematode-based bioindicators. Two long-term organically managed agroecosystems comparing plow and shallow non-inversion tillage were analyzed for free-living nematode communities. Soils out of these agroecosystems were evaluated further in a greenhouse assay for their ability to suppress pea root rot caused by Didymella pinodella, Fusarium avenaceum, and F. redolens. There was a general trend for higher levels of pea root rot disease severity following inoculations with single pathogens, however, this effect was heterogeneous among experiments and tillage systems. This was mainly due to an already very high resident population of D. pinodella in soil and the presence of seed-borne F. oxysporum determined by their high incidence in pea roots irrespective of the soil and inoculated pathogens. Additional inoculation with D. pinodella, for example, resulted in only 8.5% biomass reduction compared to the non-inoculated control, in both tillage systems. Similar biomass losses were recorded in non-inversion tilled soils inoculated with F. redolens. When analyzed across inoculation treatments, the pea root rot disease severity was only slightly reduced in non-inversion tilled soils when compared to the plough systems (11% in Exp 1 and, 9% in Exp 2), however in both experiments non-inversion tillage resulted in greater pea biomass (33 and 19% in Exp1 and 2, respectively). Furthermore, the metabolic, enrichment, and bacterivore carbon footprints of nematodes were 88, 81, and 97% higher, respectively, in the non-inversion tilled soils compared to the plough. The metabolic carbon footprint of nematodes correlated negatively with pea root rot disease severity (rho = −0.71, p = 0.047). Hence, non-inversion tillage was effective in controlling pea root rot. The use of nematode metabolic footprints for predicting soil health should be extended for various agroecosystems aiming for its general use in evaluating effects of agroecosystem management through researchers and potentially farm management advisors.

Influence of cyanobacterial inoculants, elevated carbon dioxide, and temperature on plant and soil nitrogen in soybean.

Climate change affects nitrogen dynamics in crops and diazotrophic microorganisms with carbon dioxide (CO2 ) sequestering potential such as cyanobacteria can be promising options. The interactions of three cyanobacterial formulations (Anabaena laxa, Calothrix elenkinii and Anabaena torulosa-Bradyrhizobium japonicum biofilm) on plant and soil nitrogen in soybean, were investigated under elevated CO2 and temperature conditions. Soybean plants were grown inside Open Top Chambers under ambient and elevated (550 ± 25 ppm) CO2 concentrations and elevated temperature (+2.5-2.8°C). Interactive effect of elevated CO2 and cyanobacterial inoculation through A. laxa and Anabaena torulosa-B. japonicum biofilm led to improved growth, yield, nodulation, nitrogen fixation, and seed N in soybean crop. Nitrogenase activity in nodules increased in A. laxa and biofilm treatments, with an increase of 55% and 72%, respectively, over no cyanobacterial inoculation treatment. Although high temperature alone reduced soil microbial biomass carbon, dehydrogenase activity, and soil available N, the combined effect of CO2 and temperature were stimulatory; cyanobacterial inoculation further led to an increase under all the conditions. The highest seed N uptake (758 mg plant-1 ) was recorded with cyanobacterial biofilm inoculation under elevated CO2 with control temperature conditions. The positive interactions of elevated CO2 and cyanobacterial inoculation, particularly through A. laxa and A. torulosa-B. japonicum biofilm inoculation highlights their potential in counteracting the negative impact of changing climate along with enhancing plant and soil N in soybean.

Evaluation of Liquid and Dry Chemical Treatments To Reduce Salmonella Typhimurium Contamination on Animal Food Manufacturing Surfaces

Salmonella can be isolated from animal food, ingredients, and animal food manufacturing surfaces. There are limited data regarding the sanitation of animal food manufacturing surfaces. This experiment evaluated the effects of nine chemical treatments on reduction of Salmonella Typhimurium contamination on various manufacturing surfaces. This experiment was a 9 × 5 factorial with nine chemical treatments and five surfaces. The nine chemical treatments included one with no inoculation or sanitation treatment (negative control). In the other eight treatments, inoculation with Salmonella Typhimurium was followed by either no sanitation treatment (positive control) or treatment with ground corn; liquid commercial formaldehyde; liquid food-grade sanitizer; liquid medium chain fatty acid blend of caprylic, caproic, and capric acids (MCFA); dry commercial calcium propionate; dry commercial acidulant; and dry commercial benzoic acid. The five surfaces included stainless steel, plastic, polypropylene tote bag, rubber belt, and rubber tire. Plastic had higher levels of Salmonella in the positive control than did the polypropylene tote bag; other surfaces had intermediate levels (P < 0.05). Surfaces treated with formaldehyde had no detectable Salmonella after treatment, and surfaces treated with MCFA had at least a 4-log reduction compared to the control (P < 0.05). The dry acidulant was the most effective dry sanitizer tested, but it had no impact on Salmonella concentration on rubber tires (P < 0.05). Whereas liquid sanitizers were the most effective in this experiment, they have limitations for use in dry bulk systems. In summary, formaldehyde, food-grade sanitizer, and MCFA were the most effective chemical treatments to reduce Salmonella surface contamination. Surface type can also influence Salmonella mitigation strategies; specifically, stainless steel and plastic can be more challenging to sanitize within animal food facilities.

Effect of integrated plant nutrient management on indicators related to yield and productivity of spring barley (Hordéum vulgáre) under drought conditions in the growing season

The agricultural production of the world is becoming increasingly vulnerable to extreme weather conditions, but adaptation to such conditions still suffers from a lack of integrated solutions and approaches that should cover relevant plant nutrition management issues, as well as technological mechanisms and tools. This study aimed to investigate the impact of fertilizer systems on yield indicators and the productivity of spring barley under arid growing conditions and determine the correlation between yield indicators and barley productivity to form a fertilization strategy for this crop under drought conditions. Two separate field experiments were conducted in 2018 in a small plot in six replications based on a long-term research field experiment on chernozem-type soil (black soil). As components of an integrated plant nutrient management system, the combined application of mineral fertilizers and stress protectors was used (for seed inoculation and foliar treatment), as well as the local application of mineral fertilizers at different depths (10-12 cm, 20-22 cm and at two depths simultaneously). The application of components of an integrated plant nutrient management system increased the chlorophyll content, leaf water content, and grain yield. These benefits of integrated fertilizer management led to significant improvement in grain yield. The maximum values of this indicator were noted for foliar treatment of plants by a stress protector at a rate of 1.0 L ha-1 (once per growing season) or 0.5 L ha-1 (twice per growing season) and for deep localization of mineral fertilizers (to a depth of 20-22 cm). The content of chlorophyll and bound water in the tissues of barley plants can be used as an indicator to determine the resistance of plants to arid growing conditions since these physiological characteristics are closely correlated with the yield of barley.

Inoculation effects of isolated plant growth promoting bacteria on wheat yield and grain N content

PGPB play an important role in agricultural systems, and contain broad range of bacterial genera. Therefore, in this study, seeds of wheat were inoculated with 18 rhizobacteria strains belonging to Azotobacter chroococcum (14SPI, 44SP-2, 16SP-2, 14SP2-1), Pseudomonas sp. (24A-1, 34A-2, 34SPIII, 35SP-2), Agrobacterium sp. (14A-4, 22SP-1), Rhizobium sp. (12A-3), Sphingomonas sp. (37SP), Stenotrophomonas sp. (16SP7-2), Citrobacter sp. (44 A-4S), Achromobacter sp. (14SPIII), Klebsiella oxytoca (4A-1), Beijerinckia sp. (2SP-5) and 36 A-2L isolate, to determine the effects on growth and yield of spring wheat under greenhouse condition. In this study, 18 carrier-based PGPB treatments along with one negative (B0: no inoculation) and two positive controls (B0N50 and B0N100; containing 50% and 100% of urea fertilizer, respectively) were used. The results showed that inoculation treatments had no significant effect on some plant parameters (e.g., chlorophyll index, spike length) compared with the B0, but revealed significant differences (p < .01) in other parameters such as seed weight, seed number, total dry weight, and N uptake of grain. B0N100, B0N50, and 14A-4 significantly enhanced the total dry weight (shoot, root, spike, and leave) by 35%, 32.4%, and 28.5% as compared to the control, respectively. These trends were observed in seed number and seed weight, too. Highest content of grain N uptake and Zn uptake were in 14SPI, content of P was in 44SP-2, and K and Fe content were achieved in 16SP-2 and 14SPI. In general, Agrobacterium sp. 14A-4, A. chroococcum (14SP-I, 16SP-2, and 44SP-2) were effective isolates to improve qualitative and quantitative traits of wheat.

Arbuscular Mycorrhizal Fungi Promote Gleditsia sinensis Lam. Root Growth under Salt Stress by Regulating Nutrient Uptake and Physiology

Towards the improvement of plant productivity in saline–alkali soils, the application of arbuscular mycorrhizal fungi (AMF) is an intensive topic of research. For this study, three inoculation treatments, namely, autoclaved AMF inocula (CK), Funneliformis mosseae (FM), and Corymbiglomus tortuosum (CT), and four NaCl levels, namely, 0, 50, 100, and 150 mM were established to investigate the growth and physiological responses of mycorrhizal Gleditsia sinensis Lam. root systems to increase salinity through root dry weight, morphology, nutrient content, and physiology, and soil nutrient content. As NaCl levels increased, root dry weight, morphology, and nutrient content under the CK treatment exhibited a downward trend, while FM and CT treatments weakened this trend and significantly improved root dry weight and morphology, which increased by more than 200%. Under high NaCl levels, root activity under the FM treatment was significantly higher than that under the CK, with an average increase of 120.86%. In contrast to the activity of nitrate reductase, niacinamide adenine dinucleotide oxidase activity under CK was significantly less than that in FM and CT treatments. Moreover, inoculation with AMF significantly affected soil alkali-hydrolyzable nitrogen (AN), total nitrogen (TN), and phosphorus (TP), while NaCl had no significant impact on soil nutrients. Further, both soil salinity and mycorrhizal colonization rate had significant direct effects on root growth. However, soil salinity primarily influenced root growth through indirect effects on root nitrogen content, while mycorrhizal colonization rate indirectly impacted root nitrate reductase activity, and root nitrogen and phosphorus content. Our results suggested that the use of suitable AMF (e.g., Funneliformis mosseae) might effectively improve the currently unfavorable situation of economic tree species production on land with saline soils, which may greatly optimize the utility of these areas.

Black Truffles Affect Quercus aliena Physiology and Root-Associated nirK- and nirS-Type Denitrifying Bacterial Communities in the Initial Stage of Inoculation.

Truffles (Tuber spp.) are edible ectomycorrhizal fungi with high economic value. Bacteria in ectomycorrhizosphere soils are considered to be associated with the nutrient uptake of truffles and hosts. Whether Tuber spp. inoculation can affect the growth of Quercus aliena, the ectomycorrhizosphere soil, and the rhizosphere nirK and nirS-denitrifier communities at the ectomycorrhizae formation stage is still unclear. Therefore, we inoculated Q. aliena with the black truffles Tuber melanosporum and Tuber indicum, determined the physiological activity and morphological indices of Q. aliena seedlings, analyzed the physicochemical properties of ectomycorrhizosphere soils, and applied DNA sequencing to assess the nirK and nirS- denitrifier community structure in ectomycorrhizosphere soils. Peroxidase activity was higher in the seedlings inoculated with T. melanosporum than in the T. indicum inoculation and uninoculated control treatments. The available phosphorus contents were lower and nitrate contents were higher in those with truffle inoculation, and T. melanosporum treatment differed more from the control than the T. indicum treatment. The richness of the nirK-community was highest in the T. indicum treatment and lowest in the uninoculated treatment. The differences in nirK-community composition across treatments were not statistically significant, but the nirS communities were different. The nirS-type bacteria correlated with three environmental factors (pH, available phosphorus, and nitrate contents), whereas the nirK-type bacteria were only associated with the nitrate contents. Generally, this work revealed that inoculation with Tuber spp. would change a few nutrient contents and richness of nirK-type bacteria and had little effects on growth of Q. aliena seedlings in the initial stage of inoculation. The results of this study may provide in-depth insights into the relationships between Tuber spp. and hosts, which should be taken into account when developing truffle production methods.

Ambient ultraviolet radiation: A new factor affecting anaerobic fermentation of oat and subsequent methane emissions

To investigate the effect of ambient ultraviolet (UV) radiation on the Qinghai-Tibetan Plateau on anaerobic fermentation and subsequent methane emissions, oats grown under different ambient UV conditions (UV1, 100% ambient UV radiation; UV2, 50% ambient UV radiation) were fermented with molasses and Lactobacillus plantarum (LP) inoculant treatments. The UV2 treatment increased (P < 0.05) epiphytic bacterial counts and reduced (P < 0.05) the water-soluble carbohydrate contents of oat. Both the UV2 treatment and the LP inoculant substantially increased the abundance of Lactobacillus and inhibited detrimental microorganisms (enterobacteria and yeasts) during anaerobic fermentation, resulting in the absence of butyric acid. The UV2 treatment increased (P < 0.05) the acid detergent fiber contents after anaerobic fermentation and indirectly increased (P < 0.05) methane emissions by 8.52–14.69% during in vitro ruminal digestion. This study demonstrated that low ambient UV radiation during cultivation facilitated anaerobic fermentation and consequently enhanced subsequent methane emissions from the rumen.

Cascade systems to recover resources from sludge by the integration of pretreatments to fermentation-based anaerobic bioleaching process

Future sustainable technological solutions need to balance the development of sludge as resource against the paramount necessity to protect human health and environment. Nutrients, metals, embedded energy, and the avoidance of sludge handling costs are important examples of recoverable assets. The virtuous shift to an efficient resource recovery platform should integrate pretreatments with biological conversion processes to extract values from complex waste streams as waste activated sludge. The aims of this study were: i. to assess the feasibility of sludge pretreatments as ultrasounds to promote the release of metals and organics; ii. to explore the potential of anaerobic microorganisms to leach out embedded resources from sludge through an enhanced hydrolysis/acidification step. The study proved that the acid addition to the sonicated feedstocks promoted a significant solubilization and acidification of the system during the feeding days. Crucial strategy was the inhibition of methanogens by thermal treatment of the start-up inoculum that assured pH stability, high VFAs production, and elements (As, Co and Se) solubilization. High throughput analysis of 16 S rRNA gene sequencing performed on this system revealed the presence of a high abundance of reads affiliated with hydrolytic and fermentative bacteria, in particular belonging to the phyla Bacteroidetes, Firmicutes, and Actinobacteria. The produced VFAs, fed into a semi-pilot digester with a short HRT of 15 days, were successfully converted into methane thanks to the dominant acetoclastic methanogenic population. Mass and energy balance for a full-scale scenario of this innovative biorefinery platform is reported and compared to a conventional sludge treatment scenario.

Thermal Infrared Evaluation of the Influence of Arbuscular Mycorrhizal Fungus and Dark Septate Endophytic Fungus on Maize Growth and Physiology

Thermal infrared imaging technology was used to understand the effects of arbuscular mycorrhizal fungi (AMF) and dark septate endophytic (DSE) fungi, both separately and together, on plant growth and physiological status, and to screen and develop efficient microbial agents in a pot experiment design. Eight treatments comprised the control (CK), AMF inoculation alone, DSE fungal treatments (DSE20%, DSE40% and DSE80%; 2, 4, 8 × 105 CFU mL−1) and combined inoculation treatments (DSE20% + AMF, DSE40% + AMF, and DSE80% + AMF). Canopy temperature (Tcanopy) and stomatal conductance (gs) were monitored at different growth stages, and plant biomass-related indicators were obtained at harvest. These indicators were used to assess plant growth and the physiological status resulting from the different inoculation treatments. During plant growth, the plant Tcanopy decreased following inoculation. Differences in Tcanopy between control and inoculated plants were detected by thermal infrared imaging technology and were −3.8 to + 9.3 °C (control–inoculation treatment). Growth index and Tcanopy monitoring indicate that the growth-promoting effect of combined inoculation was higher than that of either fungal type alone, with DSE80% + AMF producing the highest growth promotion. During the growth process of inoculated maize, the effect of inoculated AMF on the physiological condition of maize growth can be better monitored by thermal infrared at 10 a.m., 12 p.m., 2 p.m. and 4 p.m. on the 31st–57th days of the growth period. The method and results of this experiment are conducive to the rapid and efficient monitoring of the effects of microorganisms on plant growth and physiological status and can be applied to the screening, application, and promotion of microbial agents.

Screening of Siderophore-Producing Bacteria and Their Effects on Promoting the Growth of Plants.

Iron deficiency is a major global agricultural problem. Siderophores can help organisms to uptake iron in form of siderophore-Fe3+ complexes and then in the cell cytosol, iron is reducted and released in ferrous form. This research aimed to obtain some efficient siderophore-producing bacterial strains and evaluate their plant growth-promoting effects in the iron-deficit environment. Two strains, Brucella sp. E7 and Pseudomonas brassicae W7, were isolated from rhizosphere soil. Both strains could produce maximum siderophores under the optimal conditions. Plant promoting experiment showed that many indicators of Vigna radiata seedling were all increased significantly by strain E7/W7 or the consortium of E7 + W7. Under no-iron and high iron stress, the inoculation treatment also showed growth promotion effects on both Vigna radiata and Lolium multiflorum. These results indicated that the potential ability of strain E7 and W7 in increasing agricultural production as a growth-promoting agent in iron-deficit soil.

Nutrients Regulate the Effects of Arbuscular Mycorrhizal Fungi on the Growth and Reproduction of Cherry Tomato.

Arbuscular mycorrhizal fungi (AMF) colonize the rhizosphere of plants and form a symbiotic association with plants. Mycorrhizal symbionts have diversified ecological roles and functions which are affected by soil conditions. Understanding the effects of different AMF inoculation on plants under varied nutritional conditions is of great significance for further understanding the effects of the external environment regulating mycorrhizal symbiosis on plant phenotypic traits. In this study, the effects of four AMF inoculation treatments on the growth and reproductive performance of cherry tomato (Solanum lycopersicum var. cerasiforme) were investigated under three nutrient levels by pot experiment. It was found that the growth-promoting effect of AMF on cherry tomato decreased with nutrient reduction, and the effects of the same AMF inoculation treatment on cherry tomato were different at different nutrient levels. Nutrient levels and AMF had interactive effects on flower characteristics, fruit yield, resource allocation, and seed germination of the cherry tomato. In addition, AMF could promote sexual reproductive investment. Nutrient levels and AMF also affected the accumulation of nitrogen and phosphorus in cherry tomato, and there were significant differences among different AMF inoculation treatments. The results indicated that nutrient differences could affect the symbiosis between AMF and plants, and confirmed that there were differences in the effects of the four AMF inoculation treatments on the growth and reproductive traits of plants. The differences in growth and reproduction characteristics of cherry tomato between different AMF inoculation treatments at different nutrient levels indicated that the effects of AMF mycorrhizal on the traits of cherry tomato were regulated by nutrients.

ResidualBradyrhizobiuminoculation effects on soybean performance and selected soil health parameters

AbstractThe persistence of inoculants from year to year in soybean [Glycine max (L.) Merr.] cultivation and the residual benefits in soybean production are pertinent to adopting such practices in sub‐Saharan Africa countries such as Ghana. A study was conducted to determine the residual effect of commercial rhizobium inoculants on soybean and selected soil health parameters after three cropping seasons. The experimental design was a split‐plot. The main plot consisted of three soybean cultivars (Jenguma, Afayak, and Songda), and the subplot comprised of three peat‐based commercial bradyrhizobium inoculants (Biofix, Legumefix, and NoduMax) and an uninoculated control. Assessments were made on nodulation, shoot dry matter (DM), grain yield, grain total N uptake, permanganate‐oxidizable carbon (POXC), soil pH, and potentially mineralizable C. Among the soybean cultivars, Afayak produced greater nodule mass on the lateral root and the whole root system compared with the other cultivars. Jenguma and Afayak yielded greater shoot DM relative to Songda. Regarding the inoculants, Biofix increased nodule mass on the lateral root and the whole root system compared with the control. Biofix and NoduMax produced superior grain yield relative to the control. Biofix also produced greater grain yield than Legumefix. A superior pod harvest index and an improved grain total N uptake were produced by Biofix compared with Legumefix and the control. Commercial inoculants enhanced POXC availability at harvest, whereas potentially mineralizable C declined with inoculation treatments. Commercial inoculants (Biofix and NoduMax) enhanced nodulation, grain yield, and selected soil health indicators 3 yr after inoculation.

Optimization of the utilization of blood meal with palm oil fronds absorbance fermented as feed stuff to changes of nutrition content

The utilization of agricultural and livestock waste by-products, apart from being an alternative feed ingredient, can also reduce environmental pollution. Palm fronds as a by-product of oil palm plantations are rarely utilized and most of them will be burned and couraging climate change phenomenon. Cattle blood is a by-product of abattoirs that directly impact the environment. Most of the cattle blood not used efficiently, and pollutes the environment. The research aims to increase the use of blood meal with the absorbance of palm fronds fermented as feedstuff on changes in nutritional content. The study used a completely randomized design with a factorial pattern. Factor A is the inoculant treatment, namely A1: Bacillus amylolytic flavacient bacteria A2: Lactobacillus plantarum bacteria, factor B is the incubation time, namely: B1 = 0 hours; B2 = 60 hours and B3 = 120 hours., each treatment was repeated 3 times respectively. Parameters observed were nutrient content based on proximate analysis The results showed that there was interaction between the type of inoculant and the incubation time used in fermenting blood meal with the absorbance of palm fronds. Incubation time had a significant effect (P<0.05) on the content of dry matter, organic matter, crude fiber and crude protein, while the incubation time had no significant effect on (P>0.05) crude fat content. Based on the results of the study, it was found that in blood meal with absorbent palm oil fronds, Lactobacillus plantarum inoculants with an incubation times of 120 days gave the best results in blood meal with absorbance palm oil fronds fermented.

Effects of arbuscular mycorrhizal fungi on sugarcane growth and nutrient- related gene co-expression network under different fertilization levels

<p id="C3">Sugarcane is one of the important sugar crops in China. Arbuscular mycorrhizas (AM) fungi are widely distributed. Researches have shown that AM fungi infecting plant roots can promote nutrient absorption and growth of plants. In this study, pot experiment was used to set up with two fertilization levels of conventional fertilization (N) and reduced fertilization (R), and inoculated (AM) and control (CK). There were four treatments in total, and four replicates were set in each treatment. The results revealed that the plants inoculated with AM fungi did not only significantly increased the biomass accumulation, but also significantly affected the pH value, alkali hydrolyzable nitrogen and available phosphorus of sugarcane rhizosphere soil. The biomass accumulation in the AM fungus inoculation treatment under reduced fertilization was significantly higher than that of conventional fertilization. The turquoise module and darkgreen module with high specificity with nutrient phenotypes such as nitrogen and phosphorus were screened by weighted gene co-expression network analysis (WGCNA). The core genes of the module were screened with KME value greater than 0.7 as the threshold, and 408 and 21 core genes were screened, respectively. GO enrichment indicated that these core genes were mainly involved in nutrient transport, metabolism, and enzyme catalysis pathways. Based on annotation information and the connectivity of genes, 28 core genes related to the absorption and transportation of nutrients such as nitrogen and phosphorus and 108 related candidate genes were detected among the core genes screened. This study reveals the effects of AM fungi on sugarcane nutrient absorption, and provides a theoretical basis for further understanding of the molecular mechanisms of AM fungi affecting sugarcane nutrient absorption.

Effect of Biofertilizer and Biostimulators on Seeds germination and Seedlings growth of Albizia lebbeck L.

A factorial experiment according to Randomized Complete Blocks Design (RCBD)was conducted in Serchnar Nursery of the General Directorate of Agriculture in Sulaimani /Kurdistan Region - Iraq, to study the effect of Biofertilizer (Biohealth)at three level were using 0gmL-1 , seed inoculation in biohealth at level 10gmL-1 of distiller water, soil innoculation with biohealth 5gm in 20 litter of water) and Biosimulator( Powhumus at two concentration 0mgL-1 (0ppm) of Powhumus, irrigation with 100mgL-1 (100ppm) of Powhumus), and foliar application with Biozyme TF at two concentration 0ml L-1 and 1ml L-1 on seeds germination and seedlings growth of Albizia lebbeck. It contains the individual factors and their combinations. Data were analyzed using XLSTAT software. The results showed the superiority of the Biohealth inoculation treatment of seeds in germination percentage which recorded 93.33% and soil inoculation showed superiority in (plant height, stem diameter, percentage of P, K, fresh and dry weight of the shoot system, shoot dry matter and root fresh weight) with a score of (101.92 cm, 6.73 mm, 2.38 %, 2.61 %, 139.39 gm, 30.55 gm and 21.44%) respectively. The treatment of using Powhumus showed its superiority in the characteristics of the ( percentage of germination, percentage of N,P,K, fresh and dry weight of the shoot system, percentage of shoot dry matter, fresh and dry weight of the root system) which were recorded (88.89%, 2,30%, 0.33%, 2.43%. 104.71 g, 23.89 gm, 22.54%, 63.87%, 12.03 gm and 17.64% ) respectively. Whereas, the Biozyme treatment excelled in the traits (plant height, stem diameter, N,P and K, relative chlorophyll in leaves, fresh and dry weight of the shoot system, fresh and dry weight of the root system) which they were recorded (80.99 cm, 5.64 mm, 2.36%, 0.31%, 2.34%, 47.20, 97.82 gm, 21.81 gm, 59.57gm, and 10.08gm respectively. In the interaction between soil inoculation with biohealth, irrigation with Powhumus and foliar application with Biozyme B2P1Z1 treatment showed its superiority in the characteristics (plant height, stem diameter, percentage of N,P and K, fresh and dry weight of the shoot system, root dry weight) which were recorded (146.50%, 8.90 mm, 2.93%, 0.49, 2.97, 119.32 gm, 44.77 gm and 25.21) respectively.

First Report of Strains Within the Pythium spinosum Species Complex Causing Carrot Cavity Spot in California.

Carrots (Daucus carota L. subsp. sativus (Hoffm.)) with typical symptoms of cavity spot, i.e., sunken, round to elliptical lesions of 2-5 mm long (Hiltunen and White 2002), were collected from two locations in California, Bakersfield and Riverside, in January and July 2019, respectively. Carrots were rinsed in tap water, 4-mm2 lesion fragments were pressed into selective corn meal agar (CMA-PARP; Schrandt et al. 1994) and incubated at 23ºC in the dark for four days. Identification of pure cultures was performed via amplification and sequence analysis of two genomic regions, the Internal Transcribed Spacer 1-5.8S-ITS2 (ITS) region and the cytochrome C oxidase subunit 1 (COI) gene, using the universal primers UN-UP18S42/UN-LO28S576B (Schroeder et al. 2006) and OomCOXI-Levup/OomCOXI-Levlo (Robideau et al. 2011), respectively. Via BLAST, two isolates from organically grown carrots in Bakersfield (MCIF19) and Riverside (JSCS19), with identical ITS sequences (GenBank Acc. Nos. MZ799354 and MZ799355, respectively), showed 99.61% similarity (1021/1025 bp) to that of Pythium spinosum (AY598701.2). Yet, the COI of MCIF19 (MZ803207) showed 98.72% similarity (692/701 bp) to that of Pythium paroecandrum (GU071818.1), while the COI of JSCS19 (MZ803208) was identical (701/701 bp) to that of Pythium kunmingense (GU071820.1), a rarely isolated species considered within the species complex of P. spinosum (Robideau et al. 2011). According to these results, the isolates were identified as belonging to the P. spinosum species complex, part of Pythium Clade F (Lévesque and De Cock 2004; Robideau et al. 2011). Further research is needed to clarify the exact taxonomic status of both isolates. Koch's postulates were completed using two different assays. Each assay was done twice and with carrots of the cultivar Maverick. Surface-sterilized, freshly harvested, mature carrots, in a plastic box lined with moistened sterile paper towels, were inoculated each with four CMA plugs (5-mm diameter) with actively growing mycelium of each isolate. CMA plugs, non-inoculated or colonized by a known pathogenic P. violae strain, were used as the negative and positive control, respectively. Boxes were closed to maintain humidity and incubated at 23ºC in the dark. Lesions similar to the ones caused by P. violae were observed at day 3 for all plugs of both isolates. No symptoms were observed for the negative control, even after extending the incubation to 7 days. In a more natural assay, four non-treated carrot seeds were planted in tree seedling pots (25 x 6.5 cm) containing sterilized 50/50 peat moss/sand combined with 15-ml V8 broth (Schrandt et al. 1994) with densely grown mycelium. The same inoculation treatments were used as for the carrot disk assay. Plants (one plant/pot, four plants/treatment) were maintained at 23ºC under a 16 h photoperiod with daily watering (20 ml). At 14 weeks, the carrots inoculated with P. violae and the two test isolates showed cavity spot lesions while no symptoms were observed on carrots growing in non-inoculated medium. For both assays, pathogens were re-isolated from rinsed symptomatic tissue and their identity was confirmed using the molecular analysis described above. No oomycetes were recovered from the non-inoculated carrots. Although several Pythium species have been associated with cavity spot before, this is, to our knowledge, the first report of strains within the P. spinosum species complex causing carrot cavity spot in California and elsewhere. Funding: This research was made possible by the California Fresh Carrot Advisory Board (FRA-21).

Soybean Leaf Proteomic Profile Influenced by Rhizobacteria Under Optimal and Salt Stress Conditions.

Soil salinity is a major abiotic stressor inhibiting plant growth and development by affecting a range of physiological processes. Plant growth promoting rhizobacteria (PGPR) are considered a sustainable option for alleviation of stress and enhancement of plant growth, yet their mode of action is complex and largely unexplored. In this study, an untargeted proteomic approach provided insights into growth and stress response mechanisms elicited in soybean plants by Rhizobium sp. SL42 and Hydrogenophaga sp. SL48 and co-inoculated with Bradyrhizobium japonicum 532C. The plants were grown under optimal and salt-stressed conditions up to their mid-vegetative stage; shoot growth variables were increased in the bacteria-treated plants. Shotgun proteomics of soybean leaf tissue revealed that a number of proteins related to plant growth and stress tolerance were modulated in the bacterial inoculation treatments. Several key proteins involved in major metabolic pathways of photosynthesis, respiration, and photorespiration were upregulated. These include photosystem I psaK, Rubisco subunits, glyceraldehyde-3-phosphate dehydrogenase, succinate dehydrogenase, and glycine decarboxylase. Similarly, stress response proteins such as catalase and glutathione S-transferase (antioxidants), proline-rich precursor protein (osmolyte), and NADP-dependent malic enzyme (linked to ABA signaling) were increased under salt stress. The functions of proteins related to plant growth and stress adaptation led to an expanded understanding of plant-microbe interactions. These findings suggest that the PGPR strains regulated proteome expression in soybean leaves through multiple signaling pathways, thereby inducing salinity tolerance, and improving plant growth in the presence of this abiotic stress challenge. Data are available via ProteomeXchange with identifier PXD025596.

Cooperation between arbuscular mycorrhizal fungi and plant growth-promoting bacteria and their effects on plant growth and soil quality.

The roles of arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) in improving nutrition uptake and soil quality have been well documented. However, few studies have explored their effects on root morphology and soil properties. In this study, we inoculated Elymus nutans Griseb with AMF and/or PGPR in order to explore their effects on plant growth, soil physicochemical properties, and soil enzyme activities. The results showed that AMF and/or PGPR inoculation significantly enhanced aboveground and belowground vegetation biomass. Both single and dual inoculations were beneficial for plant root length, surface area, root branches, stem diameter, height, and the ratio of shoot to root, but decreased root volume and root average diameter. Soil total nitrogen, alkaline phosphatase, and urease activities showed significant growth, and soil electrical conductivity and pH significantly declined under the inoculation treatments. Specific root length showed a negative correlation with belowground biomass, but a positive correlation with root length and root branches. These results indicated that AMF and PGPR had synergetic effects on root morphology, soil nutrient availability, and plant growth.

Effects of Caliciopsis pinea inoculation with and without wounding on Pinus strobus

AbstractThe canker pathogen, Caliciopsis pinea, and a bast scale, Matsucoccus macrocicatrices, have been found strongly associated with dieback and mortality of eastern white pine (Pinus strobus) in the Appalachian Mountains of the United States. The scale is thought to be a wounding agent that creates infection courts for fungal pathogens like C. pinea. Inoculation tests on 3‐year‐old containerized eastern white pine seedlings were conducted with and without wounding. Puncture wound treatments designed to mimic insect wounds were applied to stems and to branch crotches. An inoculation treatment consisting of a 0.1 ml suspension containing 30,700–32,359 C. pinea ascospores was dripped on each area with puncture wounds or a nonwounded area of stems and branch crotches in two separate tests. In another series of tests, C. pinea mycelial plugs were placed on 4 mm diameter stem wounds and on nonwounded stems. Inoculation of wounds with C. pinea resulted in expanding resinous cankers, and C. pinea was reisolated from 80% to 100% of puncture wounds on stems, 40%–75% of puncture wounds on branch crotches and 100% from the 4 mm wound with mycelial inoculum. No cankers formed in nonwounded stems and branch crotches following inoculation with both types of C. pinea inoculum. The results of this study suggest that ascospores moved by water, as occurs during rains, would be able to infect small puncture wounds on a seedling stem. The tests also found that an individual C. pinea canker was not capable of girdling a seedling within a year following inoculation, suggesting that this pathogen is not particularly lethal and likely requires multiple infection courts provided by the scale to girdle branches and sapling stems.