Addition Of Fungicide Research Articles

The Application of Carbon-Based Fertilizer Changed the Microbial Composition and Co-Occurrence Network Topological Properties of Vineyard Soil

Charcoal-based fertilizer could be used extensively and is environmentally friendly. An experiment was designed to investigate the effects of different charcoal-based fertilizer application methods on soil microbiology and grape quality in a vineyard to guide the cultivation of ‘Shine-Muscat’. A control treatment without fertilization and six other treatments were set up. Four treatments applied carbon-based fertilizer as a base fertilizer with or without potassium fulvic acid, a complex microbial agent, or Bacillus subtilis, and two treatments were only applied with two applications of carbon-based fertilizer or compound fertilizer during the expansion period. The results showed that the bacterial phyla were mainly Proteobacteria and Bacteroidetes. Ascomycota, Basidiomycota, and Mortierellomycota dominated the fungal community. At the genus level, the composition of fungi, compared to bacteria, varied significantly, while the dominant flora differed among fertilization practices. Application of charcoal-based fertilizer enriched beneficial microorganisms, while chemical fertilizers enriched pathogenic microorganisms. The addition of microbial fungicides and biostimulants for a period reduced the size of the microbial network, lowered positive correlations, and enhanced resistance to adverse conditions and diseases and there was no significant correlation between agronomic traits and microbial network topology. A combination of soil microbial and grape agronomic traits suggests that a charcoal-based fertilizer base, with microbial fungicides applied, is the optimal fertilization regimen for grape.

A fluorine-free and high-robustness photothermal self-healing superhydrophobic coating with long-term anticorrosion and antibacterial performances

Superhydrophobic surface is a promising strategy for antibacterial and corrosion protection. However, the use of harmful fluorine-containing materials, poor mechano-chemical stability, the addition of fungicides and poor corrosion resistance often limit its practical application. In this paper, a high-robustness photothermal self-healing superhydrophobic coating is prepared by simply spraying a mixture of hydrophobically modified epoxy resin and two kinds of modified nanofillers (carbon nanotubes and SiO2) for long-term anticorrosion and antibacterial applications. Multi-scale network and lubrication structures formed by cross-linking of modified carbon nanotubes and repeatable roughness endow coating with high robustness, so that the coating maintains superhydrophobicity even after 100 Taber abrasion cycles, 20 m sandpaper abrasion and 100 tape peeling cycles. The synergistic effect of antibacterial adhesion and photothermal bactericidal activity endows coating with excellent antibacterial efficiency, which against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) separately reaches 99.6% and 99.8%. Moreover, the influence of modified epoxy resin, superhydrophobicity, organic coating and coating thicknesses on the anticorrosion of magnesium (Mg) alloy is systematically studied and analyzed. More importantly, the prepared coating still exhibits excellent self-cleaning, anticorrosion and antibacterial abilities after 20 m abrasion. Furthermore, the coating exhibits excellent adhesion (level 4B), chemical stability, UV radiation resistance, high-low temperature alternation resistance, stable heat production capacity and photothermal self-healing ability. All these excellent performances can promote its application in a wider range of fields.

Efficacy and phytotoxicity of various thiabendazole and tebuconazole ratios in a fungicidal mordant

When developing combined preparations, a possible phytotoxic effect should be considered, depending on the dose of the mordant. Fusarium oxysporum and Pyrenophora graminea strains were cultured in a liquid enrichment culture with the addition of fungicides at a concentration of 1.5; 2.5; 3.3 ppm. Wheat grains of the Avesta variety were treated with thiabendazole and tebuconazole in the following doses: 20 g a.d./ t, 30 g a.d./t, 60 g a.d./t, 80 g a.d./t, 100 g a.d./t of grain. The effectiveness of tebuconazole and thiabendazole on mycelium growth slightly depended on their concentration. A.d. mutually reinforced each other. The synergism of the action of two a.d. is revealed. The analysis of variance showed that the effect of tebuconazole was greater than the thiabendazole effect. For both strains, the optimal ratios of tebuconazole and thiabendazole are 1.5:2.5 ppm. The addition of salicylic acid is effective at ratios of 2.5:0 and 2.5:3.3. The mixture of thiabendazole and tebuconazole reduced the germination energy of the grains mainly due to the appearance of abnormal seedlings. A composition of active substances for seed etching is proposed, including the following ratios of components, pts. wt.: tebuconazole 20-100, thiabendazole 20-150.

The Efficiency of Fungicides on Fungal Growth Inhibition in Cultured Tissues of Banana (Musa acominata), and Their Effect on Tissues Traits

The goal of this study was to identify fungicides with a broad-spectrum effectiveness and their capacity to inhibit fungal contaminants in banana tissue cultures. Numerous fungi were isolated from tissues of banana cultures of the Grand 9 variety. Aspergillus flavus, Aspergillus niger, Cladosporium oxysporum, Penicillium digitatum, P. expansum, and Penicillium sp. were among the contaminated fungi isolated. These fungi were inhibited successfully using the fungicides Beltanol, Agrisave, and Zoxis. Hoever, Beltanol was outperformed compared with Agrisave and Zoxis fungicides, with an inhibition rate of 100% for concentrations of 0.25, 0.5, and 1 ml/l. Thus, the addition of Beltanol fungicide to the banana culture medium had a positive influence on the fresh and dry weight of the tissues, with the average fresh weight increasing to 2.93 g compared with 2.4 g in the control treatment. Also, the dry weight was increased from to 0.21 g while it was 0.17 g in the control treatment. Additionally, the results demonstrated the enzymatic effectiveness (cellulase enzyme) of isolated fungi without treatment, that showed high effectiveness in P. digitatum fungus with an activity rate reached 2.33 mm. In contrast, C. oxysporum and P. expansum fungi displayed moderate efficiency with activity rates that reached 1.5 and 1.41 mm respectively. On the other hand, A. flavus and A. niger fungi exhibited low efficacy with activity rates of 1.25 and 1.12 mm respectively. Furthermore, the results revealed that P. expansum fungus had a high enzymatic effectiveness index with a rate of 1.85 mm, while C. oxysporum, P. digitatum, and A. flavus fungi had moderate enzymatic effectiveness with rates of 1.46, 1.34, and 1.26, respectively. A. niger fungus had the lowest enzymatic effectiveness with a rate of 1.23. The enzymatic secretion of the isolated fungi was inhibited efficiently via addition of the fungicide Beltanol to these fungi.

Glomalin-related soil proteins respond negatively to fertilization and fungicide application in China's arid grassland

Glomalin-related soil protein (GRSP) are a glycoprotein mainly produced by arbuscular mycorrhizal (AM) fungi. GRSP are deposited in the soil after being released from AM fungal hyphae, and they are believed to improve soil health and carbon (C) storage. However, it is unclear how fertilizer and mycorrhiza suppression affect the content of easily extractable (EE-GRSP) and total glomalin-related protein (T-GRSP) in arid grassland soil. We conducted a 3-yr in situ study to determine the main and interactive effects of nitrogen (N), phosphorus (P), and fungicide (benomyl) addition on EE-GRSP and T-GRSP content in the soil of desert steppe in Northwest China. To further explore the mechanisms influencing GRSP content, the plant community, soil fertility and the AM fungal traits were also identified. Following 3 years of fertilizer and fungicide application, P addition had a negative influence on EE-GRSP content (−12.50%), whereas N addition had no significant effect. Fungicide application reduced EE-GRSP (−18.47%) and T-GRSP content (−18.36%) regardless of N and P addition. By altering the extraradical hyphal length of AM fungi, P and fungicide application decreased the EE-GRSP and T-GRSP content without affecting the vegetation or soil characteristics. Overall, this study provides insights into the dynamics of GRSP in response to soil nutrient enrichment and fungicide application in a resource-limited grassland ecosystem.

Variations of rhizosphere and bulk soil microbial community in successive planting of Chinese fir (Cunninghamia lanceolata).

Successive planting and monoculture, as common forest management methods, are widely used globally, especially in Chinese fir plantations in the subtropical areas of southern China. Although soil fertility depletion and productivity decline caused by successive planting have been widely reported, the underlying mechanism is still ambiguous. In this study, the composition and diversity of soil microorganisms (rhizosphere and bulk soils) in Chinese fir seedlings exposed to successive planting soils (first-generation Chinese fir seedings, FCP. second-generation Chinese fir seedings, SCP. third-generation Chinese fir seedings, TCP) and broadleaf tree species soil (Phoebe zhennan S. Lee et F. N. Wei, CK) were examined with high-throughput sequencing technology. Our findings revealed that the diversity and richness of bacterial and fungal communities were remarkably reduced in TCP than FCP and SCP, and were remarkably different between FCP and SCP. At the phylum level, the fungi with greatest relative abundance were Basidiomycota (5.74–32.88%) and Ascomycota (57.63–87.38%), while the bacteria with the greatest relative abundance were Acidobacteria (23.16–31.17%) and Proteobacteria (24.71–29.32%) for all treatments in both soil types. Additionally, the relative abundance of some pathogens (Penicillium and Burkholderia) was significantly higher in TCP than in FCP and SCP, suggesting that the presence of pathogens is an important factor in increasing the incidence of soil-borne sickness. Moreover, changes in fungal and bacterial communities were predominantly driven by soil dissolved organic carbon (DOC), DOC/DON ratio (DOCN), NO3–-N, microbial biomass carbon (MBC), and MBC/MBN ratio (MBCN). Overall, the long-term monoculture of Chinese fir promotes the microecological imbalance of rhizosphere and bulk soil, and remarkably reduced soil microbial community diversity. These results can provide a scientific support for the implementation of future management measures for fir plantations (e.g., fertilization, addition of microbial fungicides, and construction of mixed forests).

Uji Sinergitas Rendaman Tembakau (Nicotiana tabacum L.) dengan Jamur Trichoderma spp. Secara In Vitro dan Potensinya Sebagai Gabungan Biopestisida Alami

Management of plant pests and diseases can prevent crop failure of agricultural commodities. Trichoderma spp. is a type of biological control fungus. Tobacco can be used as a vegetable pesticide. However, the synergy of tobacco and Trichoderma spp. when applied simultaneously in controlling pathogens is not yet known, considering the content of the active compound nicotine in tobacco which has antifungal properties, it is necessary to conduct this study with the aim of knowing the effect of tobacco immersion on the growth of the fungus Trichoderma spp. and if there is no inhibition then both will have the potential as a combination of natural biopesticides. This study used a completely randomized design (CRD). The treatment tried was different concentrations of tobacco soak mixed with PDA as a culture medium for Trichoderma spp. The concentrations tested were 0% (T0, positive control), 5% (T1), 10% (T2), 15% (T3), and 20% (T4). The negative control used a fungicide with the active ingredient mankozeb. Each treatment was repeated 3 times. Colony thickness and color data were observed visually by descriptive method. Meanwhile, data on colony diameter, number of spores, dry weight of mycelium were analyzed by F test, if significantly different, then followed by DMRT test with a confidence level of 5%. Based on research that has been carried out from July-August 2021, the results obtained on PDA media with tobacco soaking content with concentrations of 0% (K+), 5% (T1), 10% (T2), 15% (T3), 20% (T4 ) can be grown with Trichoderma spp., while the media with the addition of synthetic fungicides made from mankozeb is not grown. The difference in concentration showed different growth results and the effective concentration in this research was 15%, because at 20% concentration there was a decrease in spore density and mycelium dry weight.

Monitoring Coffee Leaf Rust (Hemileia vastatrix) on Commercial Coffee Farms in Hawaii: Early Insights from the First Year of Disease Incursion

Coffee leaf rust (CLR, Hemileia vastatrix) is considered the most damaging coffee disease worldwide, causing reduced yields and even plant death. CLR was detected in Hawaii for the first time in 2020, and quickly spread across the state. We initiated a CLR monitoring program in Kona, West Hawaii Island, to track the spread of this new invasive disease across a broad elevational gradient. The goals of the program were to assist growers in the early detection of CLR, to characterize patterns of disease incidence across the region, and to collect information on farm agronomics, management practices, and costs to apply fungicides, all of which can be used to develop Integrated Pest Management (IPM) strategies for this pathogen. We monitored 30 coffee lots in Kona, located between 204 and 875 m elevation. Average CLR incidence remained below 4% early in the season and increased to 36% during harvest. We observed no significant difference in CLR incidence between low-, mid- and high-elevation farms. A significant reduction in the number of leaves per branch was observed at the end of the harvest season, and a significant negative correlation was found between the number of leaves per branch and maximum CLR severity. Mean disease incidence and mean severity were observed to have a significant positive correlation. Incidence increased above threshold levels (5%), despite most growers applying preventative fungicides 3–10 times throughout the season, suggesting that improved coverage and timing of applications is needed along with the addition of systemic fungicides. Our study provides the first insights into CLR disease patterns under the unique and variable conditions under which Hawaiian coffee is grown, and will aid in the development of IPM programs that can be used to sustain Hawaii’s coffee industry under this new threat.

Arbuscular mycorrhizal fungi promote small-scale vegetation recovery in the forest understorey.

Root-associating arbuscular mycorrhizal (AM) fungi foster vegetation recovery in degraded habitats. AM fungi increase nutrient availability for host plants; therefore, their importance is expected to be higher when nutrient availability is low. However, little is known about how small-scale variation in nutrient availability influences plant and AM fungal communities in a stable ecosystem. We conducted a 2-year field study in the understorey of a boreonemoral forest where we examined plant and AM fungal communities at microsites (15cm diameter) with intact vegetation cover and at disturbed microsites where vegetation was cleared away and soil was sterilized to remove soil biota. We manipulated soil nutrient content (increased with fertilizer, unchanged, or decreased with sucrose addition) and fungal activity (natural or suppressed by fungicide addition) at these microsites. After two vegetation seasons, manipulations with nutrient content resulted in significant, although moderate, differences in the content of soil nutrients (e.g. in soil phosphorus). Suppression of fungal activity resulted in lower richness, abundance and phylogenetic diversity of AM fungal community, independently of microsite type and soil fertility level. Plant species richness and diversity decreased when fungal activity was suppressed at disturbed but not in intact microsites. The correlation between plant and AM fungal communities was not influenced by microsite type or soil fertility. We conclude that small-scale variation in soil fertility and habitat integrity does not influence the interactions between plants and AM fungi. The richness, but not composition, of AM fungal communities recovered fast after small-scale disturbance and supported the recovery of species-rich vegetation.

How to cope with the vulnerability of site specific fungicides on the control of Asian soybean rust

Asian soybean rust (ASR) caused by Phakopsora pachyrhizi is the most important disease of the crop. The pathogen is highly aggressive under field conditions when the environmental conditions favor the disease development. The disease was first described in Japan, in 1902 and in 1914, it had already spread to several countries in Southeast Asia.). The first report in South America was made in Brazil in 1979 in wild soybeans and later in 2001 in the soythern area of the country in comercial plantations. P. pachyrhizi can naturally infect a wide range of plant species, including 41 species in 17 genera of the Fabaceae family. The symptoms of the disease can be seen on the abaxial and eventually on the adaxial surface of the lesions. In susceptible varieties the number of uredia per lesion varies from four to eight and the latent period around seven days. P. pachyrhizi requires more than 8 hours a day of continuous leaf wetness, and the optimal temperature for maximum germination around 22oC. There is no varieties with complete resistance to the disease available to planting. The main method of control of the disease is the application of fungicides. The main groups of fungicides to control the disease belongs to the demetilation inhibitores (DMI’s), quinone outside inhibitor (QoI’s) and carboxamides (SDHI). But with the continuous spraying with DMI’s and QoI’s alone to control ASR resistant mutants of P. pac HIhyrhizi multiplied in the population over the country. The use of mixture of DMI’S with QoI’s in the beginning proportioned resonable controle of the disease. But few years latter P. pachyrhizi acquired resistance to the mixture of triazol with stobolurins. Then it was introduced the carboxamide group (SDHI) to use in mixture with triazol with stobolurins. The triple mixture was then recommended for more a few years giving good results. Finally researchers decided to incorporate multisite fungicides in a mixture with triazol, strobilurin and or carboxamide to minimize the probability to build up resistant mutants in the population of P. pachyrhizi. The addition of multisite fungicides in a mixture with site specific is very important to reinforce the fight against fungal resistance. In conclusion to cope with the vulnerability of P. pachyrhizi to site specific fungicides the strategy has to involve integration of measures such as sanitary vacuum, rotation of a mixture of different biochemical mechanisms of action plus multisite, avoid sequential and curative applications, use of early cultivars and sowing at the beginning of the recommended season, eliminate voluntary soybean plants from the field, use of fungicides in the onset of preventively at least once before the planting lines closed, sowing at the beginning of the recommended season, and use of cultivars with resistance gene (s) to reduce the number of spraying. The present overview discuss how difficult is to cope with the resistance of P. pachyrhizi to site specific fungicides.

Biocides provide a source of carbon and nitrogen directly to surviving microbes and indirectly through a pulse in microbial necromass

Biocides have been frequently used to understand the roles of fungi and bacteria on soil carbon (C) and nitrogen (N) cycling. However, addition of biocides to soil can result in unwanted temporary increases in C and N supply to surviving microbes due to a pulse in microbial necromass, and where biocides can directly be used as sources of C and N. We assessed temporary dynamics in microbial biomass C (MBC) and N (MBN), soil respiration and gross N mineralization (GNM) during a 22-day laboratory incubation after addition of fungicides (captan, cycloheximide) and bactericides (bronopol, oxytetracycline) in a grassland soil. We also assessed whether captan and bronopol were a C source for remaining microbes based on δ13C measurements in respired CO2. As expected, fungicides decreased and bactericides increased fungi:bacteria ratios, while all biocides decreased MBC and MBN. However, respiration (except for oxytetracycline) and GNM (particularly for bronopol) increased after biocide addition, likely because of a pulse in necromass causing increased substrate supply to the surviving microbes. We further detected biocide-derived CO2 up to 10 days for captan, and 22 days for bronopol, suggesting that they can be an important source for C by surviving microbes. However, soil-derived CO2 remained higher without biocide, indicating that necromass was the most important source for higher soil respiration after biocide addition. We recommend repeated additions of biocides to suppress regrowth of target microbes, and use of 13C and 15N labeled substrates, when studying effects of fungi and bacteria on C and N dynamics.

Addition of Mancozeb to DMI + QoI, and SDHI + QoI Co-formulations Improving Control of Asian Soybean Rust

The reduced sensitivity of Phakopsora pachyrhizi to site-specific fungicides used to control Asian soybean rust by the current co-formulations needs investigation. To improve the rust control the performance of cyproconazole + picoxystrobin, tebuconazole + picoxystrobin, cyproconazole + azoxystrobin, epoxyconazole + pyraclostrobin, fluxapyroxade + pyraclostrobin, benzovindiflupyr + azoxystrobin, prothioconazole + trifloxystrobin and cyproconazole + trifloxystrobin mixtures added by five doses of the multisite mancozeb were evaluated. The fungicides were sprayed at four growth stages the first performed at R1 growth stage and the others with 15-18 days intervals. The rust severity was quantified, the control was calculated, the percentage of chlorophyll and the yield of soybean were determined. The mean of rust control by the mixtures without addition of the multi-site fungicide was 46% (21 to 71%). There was an increase in control efficiency due to addition and mancozeb doses in all treatments. Control over 80% was obtained with tebuconazole + picoxystrobin, fluxapyroxade + pyraclostrobin, benzovindiflupyr + azoxystrobin, and prothioconazole + trifloxystrobin added at least of 2.0 kg/ha mancozeb. In unsprayed plots the maximum 78% severity corresponded to 59% damage. There was an increase in chlorophyll content and soybean yield as a function of the mancozebe increased doses: 2,019 kg/ha in the unsprayed control and in the best treatment 5,132 kg/ha. Actual control reduction due to fungal decrease in sensitivity can be improved by the multi-site fungicide addition.

Flutriafol and azoxystrobin: An efficient combination to control fungal leaf diseases in corn crops

The performance of a new formulation of fungicide, azoxystrobin and flutriafol (AZXFLT), was evaluated in the control of fungal leaf spots in corn crops in Brazil. Two experiments were realized in the 2nd harvest (late growing season) in 2015 and 2016, and one in the 1st harvest (normal growing season) in 2016/2017. The area under the disease progress curve (AUDPC) was evaluated for the following leaf diseases that occurred in each experiment: northern leaf blight (Exserohilum turcicum), southern corn rust (Puccinia polysora), gray leaf spot (Cercospora zeae-maydis), maize white spot (Pantoea ananatis) and Diplodia leaf streak (Stenocarpella macrospora). The productivity and economic viability of each treatment were estimated. The experimental design was a randomized block with 4 replications. The AZXFLT formulation was evaluated at a dose of 62.5 + 62.5 g active ingredient (a.i.) ha−1 in two applications and 75 + 75 g a.i. ha−1 in one and two applications in the February 2015 and November 2016 planted experiments. In the February 2016 planted experiment, AZXFLT (75 + 75 g a.i. ha−1 in two applications) was evaluated separately and in combination with mancozeb, chlorothalonil, copper hydroxide, copper phosphite, difenoconazole and propiconazole. All fungicides reduced the AUDPC of all diseases and provided an increase in productivity, with positive financial returns when compared with treatment without fungicide. There was a greater emphasis on treatments with AZXFLT in two applications of 75 + 75 g a.i. ha−1. The addition of protective fungicides contributed to increased productivity and economic viability.

Carbon and nitrogen dynamics affected by litter and nitrogen addition in a grassland soil: Role of fungi

Fungi are critical for carbon (C) and nitrogen (N) dynamics in forest soils, but much less is known about their activity in grassland soils. Here we examined how fungal activity affected C and N cycling in a grassland soil with and without litter and N addition. Soil from a semi-natural grassland was amended with and without a fungicide (cycloheximide) to manipulate fungal activity, with and without N (20 mg N kg−1 soil as KNO3), and with and without grass litter (27 g litter kg−1 soil). Soil respiration, N2O emission, gross N mineralization, microbial biomass C (MBC) and N (MBN), available NH4+, NO3−, dissolved organic C (DOC) and N (DON) were measured during a 10-day incubation experiment. We observed that the fungicide decreased soil respiration on average by 59% but increased gross N mineralization on average by 59% with litter addition. Fungicide addition decreased N2O emission both with and without litter addition. Furthermore, N addition enhanced fungal activity, but only with litter addition when fungi became limited by N. We conclude that fungi play an important role in decomposing litter and N2O emission in grasslands but that fungal activity is sensitive to external N addition without litter inputs.

Climate change, snow mold and the Bromus tectorum invasion: mixed evidence for release from cold weather pathogens.

Climate change is reducing the depth and duration of winter snowpack, leading to dramatic changes in the soil environment with potentially important ecological consequences. Previous experiments in the Intermountain West of North America indicated that loss of snowpack increases survival and population growth rates of the invasive annual grass Bromus tectorum; however, the underlying mechanism is unknown. We hypothesized that reduced snowpack might promote B. tectorum population growth by decreasing damage from snow molds, a group of subnivean fungal pathogens. To test this hypothesis, we conducted greenhouse and field experiments to investigate the interaction between early snowmelt and either fungicide addition or snow mold infection of B. tectorum. The greenhouse experiment confirmed that the snow mold Microdochium nivale can cause mortality of B. tectorum seedlings. In the field experiment, early snowmelt and fungicide application both increased B. tectorum survival, but their effects did not interact, and snow mold inoculation had no effect on survival. We did find interactive effects of snowmelt and fungal treatments on B. tectorum seed production: with ambient snowpack, M. nivale inoculation reduced seed production and fungicide increased it, whereas in the early snowmelt treatment seed production was high regardless of fungal treatment. However, treatment effects on seed production did not translate directly to overall population growth, which did not respond to the snow melt by fungal treatment interaction. Based on our mixed results, the hypothesis that reduced snowpack may increase B. tectorum fitness by limiting the effects of plant pathogens deserves further investigation.

Micropropagation, plantlets production estimation and ISSR marker-based genetic fidelity analysis of Guadua magna and G. angustifólia

ABSTRACT The bamboo species Guadua magna and G. angustifolia have been propagated nearly exclusively by conventional techniques of vegetative propagation. Micropropagation is a promising technique and an alternative to conventional ones. This study aimed to micropropagate plants, estimate the plantlets production and analyze the genetic fidelity of G. magna and G. angustifolia by ISSR molecular markers. Mother plants of both species were cultivated in a greenhouse, and either sprayed or not with fungicide. In the laboratory, microcuttings were disinfested and established in MS culture medium with 3.0 mL L-1 of Plant Preservative Mixture (PPM®) and 1 mL L-1 of Carbendazin®. The contamination-free shoots were multiplied in liquid or semi-solid MS medium with 3.0 mg L-1 of BAP for five subcultures. Rooting was performed in liquid or semi-solid MS1/2 medium, plus 3.0 mg L-1 of IBA. Acclimatization was performed on a commercial substrate, in a growth chamber, and the genetic fidelity of the clones produced was analyzed via ISSR markers. The addition of fungicide and PPM® to the medium reduced the contamination in G. magna, but not in G. angustifolia. The liquid medium was more efficient than the semi-solid one for the multiplication of both species, which showed production potentials between 760 and 920 plants per initial microcutting, after five subcultures. Rooted plants exhibited a survival rate of up to 100 % in acclimatization. No polymorphic regions were found in the clones analyzed by ISSR at the end of the fifth subculture, suggesting that micropropagation is a safe technique for the large-scale multiplication of bamboos.

Initial state of soil microbial communities determines their stress response

The relationships between microbial communities biodiversity and soil functions are difficult to identify. In most cases, the establishment of these links requires alteration of microbial communities. In this work, we deliberately chose to subject soils to an unrealistic dose of biocide (fungicide 1000 times the recommended dose) in order to modify soil microbial communities. Two different soils were chosen from a luvisol, with contrasting land-uses: a long-term arable cropping plot (CC) and a permanent grassland (PG). Microbial communities were assessed by the measurement of the total microbial biomass via the quantification of total soil DNA. Total bacterial and fungal abundances and different bacterial taxa were measured by qPCR of rRNA genes. Results showed that fungicide stress significantly reduced total microbial and fungal biomass in PG and CC soils and decreased bacterial biomass only in CC soil. In both soils, fungicide stress decreased the abundance of Acidobacteria and Bacteroidetes. The Proteobacteria groups were insensitive or increased after fungicide addition. Enzyme activities and soil carbon mineralization were evaluated. In both soils, fungicide stress reduced cellulase, β-glucosidase and dehydrogenase activities, while N-acetyl-glucosaminidase was not affected. Xylanase activity was not affected in PG soil and it was inhibited in CC soil. Changes in structural and functional profiles of microbial communities were not correlated in the PG soil and were negatively correlated in the CC soil. To conclude, this work comfirms that the responses of microbial communities to stress depend on the nature of applied stress, measured functions and initial state of microbial communities.

Physiological potential of maize seeds submitted to different treatments and storage periods

Abstract: The aim of the study was to evaluate seed germination and vigor of maize subjected to different products and storage periods. The experimental design was completely randomized in a split plot on time. In the plots were distributed nine treatments: an untreated control, one treatment called “standard treatment”, with addition of fungicide (fludioxonil + metalaxyl-M) and insecticide (thiamethoxam). From the standard treatment, six treatments with combinations of inoculant (Azospirillum brasilense), micronutrients (nitrogen + potassium + zinc + boron + copper + iron + manganese + molibdenium) and bioregulator. Lastly, a treatment called “complete treatment” including all products. In subplots the storage periods of zero, 15, 30, 45, 60 and 90 days were evaluated. Seed vigour of maize was reduced by seed treatments and storage. Micronutrients addition resulted in higher fitotoxicity in comparison to the addition of other products, regardless of storage period. The treatment with the combination of fungicide, insecticide and inoculant proved to be feasible, and was the most promising seed treatments. None of the studied treatments affected the germination in up to 45 days of storage, however the complete treatment with 3200 mL .100 kg-1 reduced seed vigour.

<b>Population density of <i>Beauveria bassiana</i> in soil under the action of fungicides and native microbial populations

This study investigated whether populations of naturally-occurring soil bacteria, fungi and actinomycetes influence the effect of fungicides on the survival and growth of Beauveria bassiana . The toxicity of methyl thiophanate, pyraclostrobin, mancozeb and copper oxychloride at the recommended doses was analyzed in culture medium and in soil inoculated with fungus at various time points after addition of fungicides. All fungicides completely inhibited the growth and sporulation of B. bassiana in the culture medium. The fungicides were less toxic in soil, emphasizing the action of the microbial populations, which interfered with the toxic effects of these products to the fungus. Actinomycetes had the greatest influence on the entomopathogen, inhibiting it or degrading the fungicides to contribute to the survival and growth of B. bassiana in soil. Native populations of fungi and bacteria had a smaller influence on the population density of B. bassiana and the action of fungicides towards entomopathogen. The toxic effect of the fungicides was greater when added to the soil one hour before or after inoculation than at 48h after inoculation.

Fungal-mediated mortality explains the different effects of dung leachates on the germination response of grazing increaser and decreaser species

Depending on their response to grazing, grassland species can be categorized as grazing increasers or decreasers. Grazing by livestock includes several different activities that can impact species differently. Recent evidence suggest that one of these actions, dung deposition, can reduce the germinative performance of decreaser species, thus favouring increasers. The present study tested the hypothesis that decreased germinative success of decreaser species is caused by a greater activity of fungal pathogens under the influence of dung leachates. We performed a phytotron experiment analysing the germination and fungal infections of fourteen species from Mediterranean grasslands. Species were grouped into phylogenetically-related pairs, composed of an increaser and a decreaser species. Seeds of each species were germinated under four different treatments (control, dung leachate addition, fungicide addition and dung leachate and fungicide addition), and the differences in germination percentage, germination speed and infection rate between each increaser species and its decreaser counterpart were analysed. Decreaser species were more affected by mortality than increaser ones, and these differences were higher under the presence of dung leachates. The differences in germinative performance after excluding the effect of seed mortality did not differ between treatments, showing that the main mechanism by which dung leachates favour increaser species is through increased mortality of the seeds of decreaser species. Drastic reductions in the number of dead seeds in the treatments including fungicide addition further revealed that fungal pathogens are responsible for these differences between species with different grazing response. The different vulnerabilities of increaser and decreaser species to the increased activity of fungal pathogens under the presence of dung leachates seems the main reason behind the differential effect of these leachates on species with different grazing response.