Effect of foliar application of salicylic acid and mycorrhiza on quantitative and qualitative traits of maize / Efeito da aplicação foliar de ácido salicílico e micorrizas em características quantitativas e qualitativas do milho

An experiment was performed to investigate the effect of mycorrhizal symbiosis and foliar application of salicylic acid on quantitative and qualitative traits of maize during 2018 and 2019 in the research farm of Islamic Azad University, Chalous Branch. Split plot in a randomized complete block design with three replications was used. Experimental factors included mycorrhiza species of (G. mosseae), (G. geosporum) and (G. intraradices) at two levels (no consumption and consumption of mycorrhiza) and salicylic acid at two levels (no consumption and consumption of 1 mµ of salicylic acid). Results of interaction effects of mycorrhiza and salicylic acid on the measured traits revealed that the maximum 1000-grain weight, grain yield, biological yield, phosphorus, potassium, nitrogen percentage and yield of maize grain protein were observed in G. mosseae treatment under foliar application of salicylic acid. Foliar application of salicylic acid increases the root length and provides the necessary conditions for increasing water and nutrient uptake alongwith increase in photosynthesis and thus allocates more photosynthetic substance for development of reproductive organs. Hence, it increases maize grain weight and accordingly grain yield. In general, the results revealed that mycorrhiza and foliar application of salicylic acid increase growth indicators, yield and yield components. It also improved the quality traits of the maize plant. Based on results, the interaction effect of G. mosseae treatment and foliar application of salicylic acid yielded better results than other treatments. Mycorrhiza increases the number of grain in the ear, the number of rows in the ear, increases the plant's ability to absorb phosphorus, and the increase of mycorrhiza along with salicylic acid shows the maximum grain yield in maize. Finally, it can be concluded that the use of mycorrhiza and salicylic acid can be effective in increasing grain in the plant.

Um experimento foi realizado para investigar o efeito da simbiose micorrízica e aplicação foliar de ácido salicílico em características quantitativas e qualitativas do milho durante 2018 e 2019 na fazenda de pesquisa da Universidade Islâmica Azad, Chalous Branch. Foi usada uma parcela dividida em um delineamento de blocos casualizados com três repetições. Os fatores experimentais incluíram espécies de micorrizas (G. mosseae, G. geosporum e G. intraradices) em dois níveis (sem consumo e com consumo de micorrizas) e ácido salicílico em dois níveis (sem consumo e com consumo de 1 mµ de ácido salicílico). Os resultados dos efeitos da interação de micorriza e ácido salicílico nas características medidas revelaram que peso máximo de 1.000 grãos, rendimento de grãos, rendimento biológico, fósforo, potássio, porcentagem de nitrogênio e rendimento de proteína de grão de milho foram observados no tratamento G. mosseae sob aplicação foliar de ácido salicílico. A aplicação foliar de ácido salicílico aumenta o comprimento da raiz e fornece as condições necessárias para aumentar a absorção de água e nutrientes juntamente com o aumento da fotossíntese e, assim, aloca mais substância fotossintética para o desenvolvimento dos órgãos reprodutivos. Assim, aumenta o peso do grão de milho e, consequentemente, o rendimento de grãos. Em geral, os resultados revelaram que a micorriza e a aplicação foliar de ácido salicílico aumentam os indicadores de crescimento, rendimento e componentes do rendimento. Também melhoram as características de qualidade da planta de milho. Com base nos resultados, o efeito de interação do tratamento G. mosseae e aplicação foliar de ácido salicílico produziu melhores resultados do que outros tratamentos. A micorriza aumenta o número de grãos na espiga, o número de fileiras na espiga e a capacidade da planta de absorver fósforo, e o aumento da micorriza junto com o ácido salicílico mostra o rendimento máximo de grãos no milho. Por fim, pode-se concluir que o uso de micorriza e ácido salicílico pode ser eficaz no incremento de grãos na planta.

Arbuscular mycorrhizal fungi activity in the rhizosphere of tree seedlings subjected to residual herbicides / Atividade de fungos micorrízicos arbusculares na rizosfera de mudas de árvores submetidas a herbicidas residuais

Abstract Trees occurring on the margins of agricultural areas can mitigate damage from residual herbicides. Rhizospheric microbial activity associated with trees is one of the main remedial capacity indicators. The objective of this study was to evaluate the rhizospheric microbiological activity in tree species subjected to the herbicides atrazine and sulfentrazone via the rhizosphere. The experiment was designed in four blocks and a 6 × 3 factorial scheme. The first factor consisted of six tree species from Brazil and the second of atrazine, sulfentrazone, and water solutions. Four herbicide applications were performed via irrigation. The total dry mass of the plants, mycorrhizal colonization, number of spores, basal respiration of the rhizospheric soil, and survival rate of bioindicator plants after phytoremediation were determined. Trichilia hirta had higher biomass when treated with atrazine and sulfentrazone. Herbicides decreased the microbial activity in Triplaris americana and did not affect the microbiological indicators of Myrsine gardneriana, Schizolobium parahyba, and Toona ciliata. Fewer bioindicator plants survived in soil with Triplaris americana and sulfentrazone. Microbiological indicators were influenced in different ways between species by the presence of herbicides in the rhizosphere.

Resumo As árvores que ocorrem nas margens das áreas agrícolas podem mitigar os danos dos herbicidas residuais. A atividade microbiana rizosférica associada às árvores é um dos principais indicadores de capacidade corretiva. O objetivo deste trabalho foi avaliar a atividade microbiológica rizosférica em espécies arbóreas submetidas aos herbicidas atrazina e sulfentrazone via rizosfera. O experimento foi estruturado em quatro blocos e esquema fatorial 6 × 3. O primeiro fator consistiu em seis espécies de árvores do Brasil e o segundo em soluções de atrazine, sulfentrazone e água. Quatro aplicações de herbicidas foram realizadas via irrigação. Foram determinados a massa seca total das plantas, colonização micorrízica, número de esporos, respiração basal do solo rizosférico e taxa de sobrevivência de plantas bioindicadoras após fitorremediação. Trichilia hirta apresentou maior biomassa quando tratada com atrazina e sulfentrazone. Os herbicidas diminuíram a atividade microbiana em Triplaris americana e não afetaram os indicadores microbiológicos de Myrsine gardneriana, Schizolobium parahyba e Toona ciliata. Menos plantas bioindicadoras sobreviveram no solo com Triplaris americana e sulfentrazone. Os indicadores microbiológicos foram influenciados de formas distintas entre as espécies pela presença dos herbicidas na rizosfera.

Characterization of the antagonism of the mycorrhizal fungus Waitea circinata against Magnaporthe oryzae, Cochliobolus miyabeanus, Monographella albescens and Sarocladium oryzaerice pathogens / Caracterização do antagonismo do fungo micorrízico Waitea circinata contra os patógenos do arroz Magnaporthe oryzae, Cochliobolus miyabeanus, Monographella albescens e Sarocladium oryzae

Rice production is affected by important pathogens such as Magnaporthe oryzae, Cochliobolus miyabeanus, Monographella albescens and Sarocladium oryzae, and orchid mycorrhizal fungi can contribute to the biocontrol of these diseases. The aim of this study was to characterize the antagonism mechanisms of W. circinata against rice pathogens. The indoleacetic acid (IAA) and lytic enzymes of W. circinata were quantified. The effectiveness of the bioagent and its metabolites was assessed in vitro. Antagonism in vivo against rice blast was also investigated. Waitea circinata produced IAA (2.3 µg ml¹), cellulase and polyphenol oxidase in a qualitative test. Glucanase, chitinase and protease were also produced in culture with cell walls and in co-culture with pathogens to explain antibiosis. W. circinata acts on direct antagonism by antibiosis and volatile metabolites. Mycelial suspension reduced M. oryzae conidial germination, appressorium formation, and rice blast by 61, 82 and 84%, respectively. W. circinata, a unique bioagent, controls four rice pathogens from mechanisms of parasitism and antibiosis. The results could contribute to new formulations containing this fungus, enzymes as well as its volatile metabolites.

A produção de arroz é afetada por patógenos importantes como Magnaporthe oryzae, Cochliobolus miyabeanus, Monographella albescens e Sarocladium oryzae, e fungos micorrízicos de orquídeas podem contribuir para o biocontrole dessas doenças. O objetivo deste estudo foi caracterizar os mecanismos de antagonismo de W. circinata contra patógenos do arroz. O ácido indolacético (AIA) e as enzimas líticas de W. circinata foram quantificadas. A eficácia do bioagente e seus metabólitos foi avaliada in vitro. O antagonismo in vivo contra a brusone do arroz também foi investigado. Waitea circinata produziu AIA (2,3 µg ml¹), celulase e polifenol oxidase em teste qualitativo. Glucanase, quitinase e protease também foram produzidas em cultura com paredes celulares e em co-cultura com patógenos para explicar a antibiose. W. circinata atua no antagonismo direto por antibiose e metabólitos voláteis. A suspensão micelial reduziu a germinação de conídios de M. oryzae, a formação de apressórios e a brusone do arroz em 61, 82 e 84%, respectivamente. W. circinata, um bioagente único, controla quatro patógenos do arroz a partir de mecanismos de parasitismo e antibiose. Os resultados podem contribuir para novas formulações contendo este fungo, enzimas, bem como seus metabólitos voláteis.

Arbuscular mycorrhizal fungi in wheat grown in copper contaminated soil / Fungos micorrízicos arbusculares no cultivo de trigo em solo contaminado com cobre

At high soil concentrations, copper (Cu) is toxic to plant development. Symbiosis carried out between microorganisms and plant species are alternatives to minimize plant toxicity in copper contaminated soil. The present study aimed to select species of arbuscular mycorrhizal fungi for the development of wheat plants in copper contaminated soil. The experimental design was completely randomized in a 4 × 6 factorial arrangement, with four sources of inocula: three species of arbuscular mycorrhizae (Acaulospora colombiana, Gigaspora Margarita and Rhizophagus clarus) and one without inoculum (control), and six doses of copper in the soil (0, 80, 160, 240, 320, and 400 mg kg-1), with seven replications. Plant height, root length, root volume, root dry mass, specific surface area, average root diameter, root, shoot and grain Cu content and mycorrhizal colonization rate were evaluated. Root dry mass and mycorrhizal colonization were negatively affected by high Cu doses in the soil. The mycorrhizal isolates Acaulospora Colombiana and Gigaspora Margarita provide greater wheat height, root length and specific surface area and lower Cu content. Mycorrhizal colonization with the fungi Acaulospora Colombiana, Gigaspora Margarita and Rhizophagus clarus results in lower copper content in wheat shoots and grains.(AU)

Em elevadas concentrações no solo, o cobre (Cu) é tóxico para o desenvolvimento dos vegetais. Simbioses realizadas entre microrganismos e espécies vegetais são alternativas para minimizar a toxidez das plantas em solo contaminado com cobre. O trabalho teve como objetivo selecionar espécies de fungos micorrízicos arbusculares para o desenvolvimento de plantas de trigo em solo contaminado com cobre. O delineamento experimental foi inteiramente casualizado em arranjo fatorial 4 × 6, sendo quatro fontes de inóculos: três espécies de micorrizas arbusculares (Acaulospora colombiana, Gigaspora margarita e Rhizophagus clarus) e sem inóculo (testemunha) e seis doses de cobre no solo (0, 80, 160, 240, 320 e 400 mg kg-1), com sete repetições. Avaliou-se a altura de plantas, comprimento de raiz, volume de raízes, massa seca de raiz, área superficial específica, diâmetro médio de raiz, teor de cobre na raiz, na parte aérea e no grão e porcentagem de colonização micorrízica. A massa seca de raiz e a colonização micorrízica foram afetadas negativamente com altas doses de Cu no solo. Os isolados micorrízicos Acaulospora Colombiana e Gigaspora Margarita proporcionam maior altura, comprimento de raiz e área superficial específica e menor teor de Cu no grão na cultura do trigo. A colonização micorrízica com os fungos Acaulospora Colombiana, Gigaspora Margarita e Rhizophagus clarus resulta em menor teor de cobre na parte aérea e nos grãos do trigo.(AU)

Genetic and symbiotic characterization of rhizobia nodulating legumes in a mining area in southeast Brazil

Identification and selection of nitrogen-fixing bacterial strains for inoculation into native leguminous tree species can assist in the recovery of degraded areas. Additionally, native strains from these areas are genetic resources adapted to these conditions and are thus suitable for selection. The aim of this study was to symbiotically and genetically characterize 18 bacterial strains from the Rhizobium and Bradyrhizobium genera isolated from Machaerium nyctitans, Platypodium elegans, and Ormosia arborea grown in a nursery in an iron mining area. Three experiments were conducted under axenic conditions in a greenhouse. The nodulation capacity of the strains was evaluated by the number (NN) and dry matter (NDM) of nodules. Symbiotic efficiency was evaluated based on the following parameters: SPAD index (SPAD), shoot dry matter (SDM), root dry matter (RDM), and total dry matter (TDM) of the plants, relative efficiency (RE), shoot nitrogen content (SNC), and total nitrogen content in the plant (TNC). The atpD and gyrB housekeeping genes and the nifH gene were sequenced for phylogenetic analysis, and the nodC and nodD symbiotic genes of the strains were amplified. Out of the 18 strains, 16 were authenticated by nodulation capacity in the species of origin. The SPAD variable allowed for the detection of differences between treatments before the SDM. Additionally, the SPAD index showed correlation with TNC, and the strain Bradyrhizobium sp., UFLA01-839, which may represent a new species, was outstanding in Machaerium nyctitans. The nifH, nodD, and nodC genes were detected in UFLA01-839.

Micorrização e respiração microbiana do solo sob o cultivo de maracujá e pinhão manso em diferentes regimes hídricos / Mycorrization and microbial respiration in soil under passion fruit and jatropha in different water regimes

Os fungos micorrízicos arbusculares (FMAs) e a população microbiana do solo ocupam papel de destaque em amenizar os efeitos causados pelo estresse hídrico em diversas culturas, entretanto se faz necessário estabelecer parâmetros sobre a dinâmica da interação desses microrganismos com as plantas em condições de estresse. Diante do exposto, o trabalho teve por objetivo avaliar a micorrização ea respiração microbiana do solo cultivado com mudas de maracujá amarelo e pinhão manso submetidas a diferentes níveis de água. O experimento foi realizado em vasos na casa de vegetação localizada na Universidade Estadual de Goiás, unidade de Ipameri. O delineamento utilizado foi inteiramente casualizado, e analisado em um esquema fatorial 2 x 7 sendo duas espécies de plantas (maracujá e pinhão manso) e sete níveis de fornecimento de água (25%, 50%, 75%, 100%, 125%, 150% e 175%) em relação a capacidade de campo (CC) do solo com cinco repetições, totalizando 70 parcelas experimentais de cultivo. Foram avaliadas a respiração microbiana do solo (RM), número de esporos micorrízicos (ESP) e colonização micorrízica (CM). Em termos de RM os solos responderam de forma distinta a alteração da umidade do solo, onde a microbiota do solo com pinhão manso se mostrou mais adaptada até aos 175% da CC que do maracujá. A condição de excesso hídrico provocou uma diminuição no ESP do solo de ambas a culturas, porém com efeito sendo mais significativo na cultura do maracujá que apresentou uma média de 77,2 esporos 50g-1 de solo. A CM do pinhão manso e do maracujazeiro foram afetadas negativamente com o aumento dos níveis de umidade do solo, porém o pinhão manso apresentou em média uma taxa de CM 38,5% maior que o maracujá. De maneira geral a microbiota do solo e os FMAs sob mudas de pinhão manso responderam melhor ao estresse hídrico.(AU)

Arbuscular mycorrhizal fungi (AMF) and the soil microbial population occupy a prominent role in mitigating the effects caused by water stress in several crops. However, it is necessary to establish parameters on the dynamics of the interaction of these microorganisms with plants under stress conditions. Given the above, this study aimed to evaluate the mycorrhization and microbial respiration of soil cultivated with yellow passion fruit and jatropha seedlings subjected to different water levels. The experiment was carried out in pots in a greenhouse located at the State University of Goiás, Ipameri unit. The design used was completely randomized and analyzed in a 2x 7 factorial scheme with two plant species (passion fruit and Jatropha curcas) and seven levels of water supply (25%, 50%, 75%, 100%, 125%, 150% and,175%) in relation to the field capacity (FC) of the soil with five replications, totaling 70 experimental cultivation plots. In addition, soil microbial respiration (MR), number of mycorrhizal spores (SPO) and mycorrhizal colonization (MC) were also evaluated. In terms of MR, the soils responded differently to changes in soil moisture, where the microbiota of the soil with Jatropha curcaswas more adapted up to 175% of CC than that of passion fruit. The excess water condition caused a decrease in the SPOof the soil of both crops, but with an effect being more significant in the passion fruit crop, which presented an average of 77.2 spores 50g-1of soil. The MC of Jatropha curcasand passion fruit were negatively affected with the increase of soil moisture levels, however,the Jatropha curcaspresented an average rate of MC 38.5% higher than the passion fruit. In general, the soil microbiota and the AMF under Jatropha seedlings responded better to water stress.(AU)

Beneficial services of Glomalin and Arbuscular Mycorrhizal fungi in degraded soils in Brazil

Reducing soil degradation and its impacts on the environment have been one of the main challenges of the 21st century, exacerbated by a direct link between increases in the human population and soil degradation that raises current and future food security concerns. Despite this, experiences worldwide reveal that degraded land restoration projects have either achieved little success or failed. Thus, understanding the underlying causes and devising appropriate restoration mechanisms is crucial. Soil amelioration using beneficial microorganisms, particularly arbuscular mycorrhizal fungi (AMF), is essential and pragmatic. Glomalin, a type of glycoprotein produced by arbuscular mycorrhizal fungi in the phylum Glomeromycota, contributes to the mitigation of soil degradation. Moreover, AMF and glomalin are highly correlated with other soil physico-chemical parameters and are sensitive to changes in the environment. As a result of this, they have been recommended for monitoring the recovery of degraded soil or stages of soil degradation. In this review, we discuss the role of AMF and glomalin in the restoration of degraded soils, including improvements to the soil structure and soil organic matter (SOM), microbial activity, reduction of fertility loss, bioremediation, and mitigation of the effects of drought and saline stress. We highlight the research gaps and discuss the prospects. This knowledge will improve our understanding of the ecological conduct of glomalin and AMF, stimulate future research, and be useful to sustainable restoration of degraded lands. Furthermore, we discussed the challenges and obstacles in the legislation and future perspectives on the production of inoculants based on AMF in Brazil.

Inoculation of arbuscular mycorrhizal fungi as a strategy to improve annatto (Bixa orellana L. ) growth

This study aimed to assess the occurrence of arbuscular mycorrhizal fungi (AMF) in annatto (Bixa orellana L.) cultivars and their response to AMF inoculation using biometric parameters. The occurrence surveys were conducted in annatto fields in three municipalities from Pernambuco Forest Zone: Lagoa de Itaenga, Gloria de Goitá, and Vitoria de Santo Antão, and in four cultivars (Red Piave, Green Piave, Red Peruvian Paulista, and Green Peruvian Paulista). In a greenhouse, biometric parameters of annatto seedlings of Red Piave, Red Peruvian Paulista, Embrapa-36, and Embrapa-37 cultivars inoculated with AMF isolated from annatto fields. The Red Piave cultivar exhibited greater root colonization than the Green Peruvian Paulista in the Lagoa de Itaenga and Vitoria de Santo Antão municipalities. The cultivar Red Piave showed a more beneficial association with AMF in plants and soil than cultivar Green Peruvian Paulista did, in both Lagoa de Itaenga and Vitoria de Santo Antão. AMF inoculation was effective in promoting the growth of annatto plants, particularly those inoculants with S. heterogama and C. etunicatum.

Inoculation of arbuscular mycorrhizal fungi as a strategy to improve annatto (Bixa orellana L. ) growth

This study aimed to assess the occurrence of arbuscular mycorrhizal fungi (AMF) in annatto (Bixa orellana L.) cultivars and their response to AMF inoculation using biometric parameters. The occurrence surveys were conducted in annatto fields in three municipalities from Pernambuco Forest Zone: Lagoa de Itaenga, Gloria de Goitá, and Vitoria de Santo Antão, and in four cultivars (Red Piave, Green Piave, Red Peruvian Paulista, and Green Peruvian Paulista). In a greenhouse, biometric parameters of annatto seedlings of Red Piave, Red Peruvian Paulista, Embrapa-36, and Embrapa-37 cultivars inoculated with AMF isolated from annatto fields. The Red Piave cultivar exhibited greater root colonization than the Green Peruvian Paulista in the Lagoa de Itaenga and Vitoria de Santo Antão municipalities. The cultivar Red Piave showed a more beneficial association with AMF in plants and soil than cultivar Green Peruvian Paulista did, in both Lagoa de Itaenga and Vitoria de Santo Antão. AMF inoculation was effective in promoting the growth of annatto plants, particularly those inoculants with S. heterogama and C. etunicatum.(AU)

Development of mycorrhizal soybean grown in coppercontaminated soil / Desenvolvimento da soja micorrízada cultivada em solo contaminado com cobre

High concentrations of copper in the soil are toxic to the development of plants and microorganisms. The aim of this study was to select arbuscular mycorrhizal fungi efficient for the development and yield of soybeangrown in copper-contaminated soil. The experiment was laid out in a completely randomized design with a 7 × 4 factorial arrangement corresponding to seven rates of copper (0, 80, 160, 240, 320, 400, and 480 mg kg-1 of soil) and four inocula (uninoculated control and three mycorrhizal fungi, namely, Acaulospora colombiana, Dentiscutata heterogama and Rhizophagus clarus), in seven replicates. Shoot height; collar diameter; number of grains per plant; shoot and root-system dry mass; leaf area; specific root surface; copper content and accumulation in the shoots, roots, and grain; chlorophyll parameters; and mycorrhizal colonization percentage were evaluated. Inoculation with the arbuscular mycorrhizal fungi Acaulospora colombiana, Dentiscutata heterogama and Rhizophagus clarus increases the phenological and physiological parameters of soybean and its yield when grown in soil contaminated with up to 480 mg kg-1 of copper applied to the soil. The Rhizophagus clarus isolate provides greater development and yield in soybean grown in soil contaminated with up to 480 mg kg-1 of copper applied to the soil, as compared with the other isolates.(AU)

O cobre em elevada concentração no solo torna-se tóxico ao desenvolvimento das plantas e microrganismo. O trabalho objetivou selecionar fungos micorrízicos arbusculares eficientes para o desenvolvimento e produtividade da soja cultivada em solo contaminado com cobre. O delineamento experimental foi em Inteiramente casualizado em arranjo fatorial 7 × 4, sendo, sete doses de cobre (0, 80, 160, 240, 320, 400 e 480 mg de cobre kg-1 de solo), quatro inóculos (testemunha sem inoculação e três fungos micorrízicos: Acaulospora colombiana, Dentiscutata heterogama e Rhizophagus clarus), com 7 repetições. Avaliou-se a altura da parte aérea, diâmetro do colo, número de grão por planta, massa seca da parte aérea e sistema radicular, área foliar, área superficial específica de raízes, teores e acúmulo de cobre na parte aérea, radicular e no grão, parâmetros da clorofila, e porcentagem de colonização micorrízica. A inoculação com fungos micorrízicos arbusculares Acaulospora colombiana, Dentiscutata heterogama, Rhizophagus clarus aumenta os parâmetros fenológicos e fisiológicos da soja e a sua produtividade soja em solo contaminado com até 480 mg kg-1 de cobre aplicado no solo. O isolado Rhizophagus clarus promove maior desenvolvimento da soja e aumenta sua produtividade em solo contaminado com até 480 mg kg-1 de cobre aplicado no solo em relação aos demais isolados.(AU)

Cover cropping system and mulching can shape soil microbial status in fruit orchards

The use of cover crop in agricultural fields has been well elucidated, especially regarding nitrogen fixation from legume crops and their function as weed protection. Furthermore, to cover crops can benefit the soil microbial community. This study aimed to evaluate and compare the benefits of mulching and cover cropping systems on soil microbial growth and activity, and their effects on plant mineral nutrition in pomelo (Citrus maxima ) and macadamia ( Macadamia integrifolia ) orchards. The treatments included: 1) control [Glyphosate herbicide (Roundup at 4 l per ha)], 2) manual weed control, 3) mulching with dead leaves from their respective trees (macadamia and pomelo), 4) millet, 5) faba bean, 6) millet + faba bean. All the treatments were applied for 120 days before soil and plant leaves were sampled for analyses. Plant mineral nutrition, soil microbial biomass C (MBC) and soil microbial biomass N (MBN); basal respiration (BRA), arbuscular mycorrhizal fungi (AMF) colonization (COL); number of AMF spores (SPO) in soil; total organic carbon (TOC) and total nitrogen (TN) were evaluated. Plant nutrition was not altered by the treatments; however, the MBC, COL and SPO markedly increased in response to mulching and faba bean + millet treatments. Especially in macadamia soils, these treatments had a great response to soil microbiology. Significant negative correlations were also detected for the COL, SPO, BRA and TOC with the Nutrient Balance Index (NBI). These results indicate that in short-term the cover cropping system is useful to improve the soil microbial growth and AMF formation in soils of pomelo and macadam orchards.

Cover cropping system and mulching can shape soil microbial status in fruit orchards

The use of cover crop in agricultural fields has been well elucidated, especially regarding nitrogen fixation from legume crops and their function as weed protection. Furthermore, to cover crops can benefit the soil microbial community. This study aimed to evaluate and compare the benefits of mulching and cover cropping systems on soil microbial growth and activity, and their effects on plant mineral nutrition in pomelo (Citrus maxima ) and macadamia ( Macadamia integrifolia ) orchards. The treatments included: 1) control [Glyphosate herbicide (Roundup at 4 l per ha)], 2) manual weed control, 3) mulching with dead leaves from their respective trees (macadamia and pomelo), 4) millet, 5) faba bean, 6) millet + faba bean. All the treatments were applied for 120 days before soil and plant leaves were sampled for analyses. Plant mineral nutrition, soil microbial biomass C (MBC) and soil microbial biomass N (MBN); basal respiration (BRA), arbuscular mycorrhizal fungi (AMF) colonization (COL); number of AMF spores (SPO) in soil; total organic carbon (TOC) and total nitrogen (TN) were evaluated. Plant nutrition was not altered by the treatments; however, the MBC, COL and SPO markedly increased in response to mulching and faba bean + millet treatments. Especially in macadamia soils, these treatments had a great response to soil microbiology. Significant negative correlations were also detected for the COL, SPO, BRA and TOC with the Nutrient Balance Index (NBI). These results indicate that in short-term the cover cropping system is useful to improve the soil microbial growth and AMF formation in soils of pomelo and macadam orchards.(AU)

Mycorrhization and saline stress response in Hyptis suaveolens / Micorrização e resposta ao estresse salino em Hyptis suaveolens

The objective of this study was to evaluate the physiological and biochemical mechanisms of adaptation of Hyptis suaveolens under osmotic stress due to salinity inoculations with a mycorrhizal fungal species. H. suaveolens seeds were germinated in polyethylene pots containing a substrate associated with or without arbuscular mycorrhizal fungi (AMF). After plant formation, treatments were treated with different salt concentrations (0.0, 35, 70, and 105 mM) and fungi (control and two types of AMF), totaling 12 treatments with three replicates. The experimental design used randomized blocks in a 4 x 3 factorial scheme, totaling 12 treatments with three replicates each. Salinity affected all measured physiological and biochemical variables, and the stress reduced dry matter content. Plants associated with AMF had increased dry matter compared to non-associated plants, and there were increased biochemical and physiological responses of AMF-colonized plants in the 35 mM NaCl treatment. However, saline stress negatively affected the development of H. suaveolens; and therefore, no attenuation of fungi was observed.(AU)

Este estudo teve como objetivo avaliar mecanismos fisiológicos e bioquímicos de adaptação de Hyptis suaveolens submetidas ao estresse osmótico decorrente da salinidade inoculadas com espécies de fungos micorrízicos. Sementes de H. suaveolens foram colocadas para germinar em vasos de polietileno contendo substrato associado, ou não, a FMA. Após o estabelecimento das plantas, foram iniciados os tratamentos com diferentes concentrações de sais (0,0; 35; 70 e 105 mM) e fungos (controle e dois tipos de FMA), perfazendo 12 tratamentos com três repetições. O delineamento experimental foi em blocos casualizados em esquema fatorial 4 x 3, perfazendo 12 tratamentos com três repetições cada. Observou-se, através de variáveis fisiológicas e bioquímicas, que a salinidade afetou todas as variáveis analisadas e o estresse promoveu redução no conteúdo de matéria seca. Verificou-se que plantas associadas com FMA apresentaram ganho de matéria seca em relação as não associadas e incremento de respostas bioquímicas e fisiológicas das plantas colonizadas no tratamento 35mM de NaCl. No entanto, o estresse salino afeta negativamente o desenvolvimento de H. suaveolens não sendo observado, portanto, atenuação dos fungos.(AU)

Yield increase of corn inoculated with a commercial arbuscular mycorrhizal inoculant in Brazil / Rendimento de grãos da cultura do milho com inoculante micorrízico arbuscular comercial no Brasil

Arbuscular mycorrhizal fungi (AMF) play an important role in plant growth. However, there are no reports of legally commercialized AMF-based inoculants for agricultural crops in Brazil. The objective of this research was to evaluate the agronomic efficiency of a Rhizophagus intraradices inoculant in combination with phosphate fertilization in grain yield of corn under different edaphoclimatic conditions in Brazil. Experiments were conducted in five Brazilian states (Goiás, Mato Grosso, Minas Gerais, Rio Grande do Sul and Santa Catarina) in a 2 x 3 factorial scheme, with two inoculation treatments (inoculated and non-inoculated seeds) and three doses of phosphate fertilization (0, 50 and 100% of the recommended P). At the end of the crop cycle (stages R4-R5), inoculation provided increases in biomass (average of 48%) regardless of the applied dose of P, higher P absorption, and 54% average increase in grain yield. In conclusion, the mycorrhizal inoculant increases biomass yield, P uptake and corn grain yield under different edaphoclimatic conditions in Brazil, especially in soils that originally had low or medium levels of available P.(AU)

Os fungos micorrízicos arbusculares (FMA) desempenham um papel importante no crescimento das plantas, no entanto, não há relatos de inoculantes legais baseados em AMF para culturas agrícolas no Brasil. O objetivo deste trabalho foi avaliar a eficiência agronômica de um inoculante a base de Rhizophagus intraradices em combinação com a adubação fosfatada no rendimento de grãos de milho sob diferentes condições edafoclimáticas no Brasil. Os experimentos foram conduzidos em cinco estados brasileiros (Goiás, Mato Grosso, Minas Gerais, Rio Grande do Sul e Santa Catarina) em esquema fatorial 2 x 3, com dois tratamentos de inoculação (sementes inoculadas e não inoculadas) e três doses de adubação fosfatada (0, 50 e 100% do P recomendado). No final do ciclo da cultura (estágios R4-R5), a inoculação proporcionou aumentos na biomassa (média de 48%), independentemente da dose aplicada de P, maior absorção de P e aumento médio de 54% no rendimento de grãos. Conclui-se que o inoculante micorrízico arbuscular aumenta a produção de biomassa, a absorção de P e a produtividade de grãos de milho em diferentes condições edafoclimáticas no Brasil, especialmente em solos que originalmente apresentavam níveis baixos ou médios de P.(AU)

Produtividade da soja em associação ao fungo micorrízico arbuscular Rhizophagus clarus cultivada em condições de campo / Production of soybean in association with the arbuscular mycorrhizal fungi Rhizophagus clarus cultivated in field conditions

A soja é fundamental para o progresso do agronegócio, porém sua produtividade pode ser afetada pelas mudanças climáticas. Assim, alternativas que aumentem o rendimento das plantas em condições adversas são fundamentais, e os fungos micorrízicos arbusculares (FMA) destacam-se, pois, associam-se as raízes das plantas aumentando a absorção de água e nutrientes. Assim, o objetivo deste trabalho foi avaliar a produtividade de plantas de soja a campo experimental em associação com o FMA Rhizophagus clarus sob condição de sistema irrigado e não irrigado. Ao final, avaliou-se parâmetros agronômicos e de simbiose com o FMA. O delineamento experimental foi em blocos casualizados com parcelas subdivididas, as médias obtidas foram submetidas à análise de variância e comparadas pelo teste Tukey (5%), utilizando software SISVAR. Plantas de soja quando associadas com FMA e cultivadas em condição não irrigada, obtiveram maior produtividade do que plantas no sistema irrigado, além de peso de 1000 grãos. Desta forma, conclui-se que a inoculação beneficia a produtividade da soja em condições de sistema não irrigado.(AU)

Soybeans are key to agribusiness progress, but their production can be affected by climate change. Thus, alternatives that increase the yield of the plants under adverse conditions are fundamental, and the arbuscular mycorrhizal fungi (FMA) stand out. Therefore, they associate the roots of the plants, increasing the absorption of water and nutrients. Thus, the objective of this work was to evaluate soybean yield in the field experiment in association with FMA Rhizophagus clarus under conditions of irrigated and nonirrigated system. In the end, agronomic and symbiosis parameters were evaluated with FMA. The experimental design was in randomized blocks with subdivided plots, the means obtained were submitted to analysis of variance and compared by the Tukey test (5%), using SISVAR software. Soybean plants when associated with FMA and cultivated in non-irrigated conditions, obtained higher productivity than plants in the irrigated system and weight of 1000 grains. In this way, it is concluded that inoculation benefits soybean yield under non-irrigated system conditions.(AU)

Produtividade da soja em associação ao fungo micorrízico arbuscular Rhizophagus clarus cultivada em condições de campo / Production of soybean in association with the arbuscular mycorrhizal fungi Rhizophagus clarus cultivated in field conditions

A soja é fundamental para o progresso do agronegócio, porém sua produtividade pode ser afetada pelas mudanças climáticas. Assim, alternativas que aumentem o rendimento das plantas em condições adversas são fundamentais, e os fungos micorrízicos arbusculares (FMA) destacam-se, pois, associam-se as raízes das plantas aumentando a absorção de água e nutrientes. Assim, o objetivo deste trabalho foi avaliar a produtividade de plantas de soja a campo experimental em associação com o FMA Rhizophagus clarus sob condição de sistema irrigado e não irrigado. Ao final, avaliou-se parâmetros agronômicos e de simbiose com o FMA. O delineamento experimental foi em blocos casualizados com parcelas subdivididas, as médias obtidas foram submetidas à análise de variância e comparadas pelo teste Tukey (5%), utilizando software SISVAR. Plantas de soja quando associadas com FMA e cultivadas em condição não irrigada, obtiveram maior produtividade do que plantas no sistema irrigado, além de peso de 1000 grãos. Desta forma, conclui-se que a inoculação beneficia a produtividade da soja em condições de sistema não irrigado.

Soybeans are key to agribusiness progress, but their production can be affected by climate change. Thus, alternatives that increase the yield of the plants under adverse conditions are fundamental, and the arbuscular mycorrhizal fungi (FMA) stand out. Therefore, they associate the roots of the plants, increasing the absorption of water and nutrients. Thus, the objective of this work was to evaluate soybean yield in the field experiment in association with FMA Rhizophagus clarus under conditions of irrigated and nonirrigated system. In the end, agronomic and symbiosis parameters were evaluated with FMA. The experimental design was in randomized blocks with subdivided plots, the means obtained were submitted to analysis of variance and compared by the Tukey test (5%), using SISVAR software. Soybean plants when associated with FMA and cultivated in non-irrigated conditions, obtained higher productivity than plants in the irrigated system and weight of 1000 grains. In this way, it is concluded that inoculation benefits soybean yield under non-irrigated system conditions.

Adaptabilidade de clones de eucalipto à inoculação de fungos micorrízicos em solo arenoso em São Domingos do Araguaia – PA / Adaptability of eucalyptus clones to the inoculation of mycorrhizal fungi in sand soil in São Domingos do Araguaia – PA

Atualmente, as espécies do gênero Eucalyptus figuram nas espécies mais importantes nas plantações florestais comerciais. Estas espécies apresentam dependência de associação micorrízica para o crescimento em condições de campo. Este estudo teve como objetivo avaliar a adaptabilidade de clones de eucalipto sob inoculação de fungos micorrízicos na região de Marabá, sudeste do estado do Pará, Brasil. O experimento foi instalado em delineamento de blocos ao acaso com três repetições, com 12 tratamentos e seis clones. O espaçamento das mudas foi de 3,0 x 3,0 metros, cada parcela com 56 árvores, sendo a metade inoculada com fungos micorrízicos (endomicorrízico e ectomicorrízico). A outra metade das mudas não foi inoculada e funcionou como controle. Cada clone continha 168 indivíduos, totalizando 1008 mudas de clones de eucalipto. A inoculação com isolados micorrízicos não promoveu o maior crescimento em diâmetro e altura dos clones. Os clones: híbrido de Eucalyptus urophylla x Eucalyptus camaldulensis (VM01), de Eucalyptus platyphylla (373) e híbrido de Eucalyptus urophylla x Eucalyptus grandis (1250) apresentaram as menores taxas de mortalidade. Portanto, os clones mais recomendados para a região de estudo foram: híbrido de Eucalyptus urophylla x Eucalyptus camaldulensis (VM01), híbrido de Eucalyptus urophylla x Eucalyptus grandis (A217), Eucalyptus platyphylla (373) e híbrido de Eucalyptus urophylla x Eucalyptus grandis (1250) devido aos seus maiores valores em diâmetro, altura e menor taxa de mortalidade.

Currently, the species of the genus Eucalyptus figure among the most important species for commercial forest plantations. These species present dependence on mycorrhizal association to grow in field conditions. This study had the objective to evaluate the adaptability of eucalyptus clones under inoculation of mycorrhizal fungi in the Marabá region, southeastern Pará state, Brazil. The experiment was set up in a complete random block design with three replicates, with 12 treatments, and six clones. Seedling spacing was 3.0 x 3.0 meters, each plot with 56 trees, where half of them were inoculated with mycorrhizal fungi (endomycorrhizal and ectomycorrhizal). The other half of the seedlings were not inoculated and worked as control. Each clone had 168 individuals, totalizing 1008 seedlings of eucalyptus clones. Inoculation with mycorrhizal isolates did not promote the highest growth in diameter and height of the clones. The clones: hybrid of Eucalyptus urophylla x Eucalyptus camaldulensis (VM01), Eucalyptus platyphylla (373) and hybrid of Eucalyptus urophylla x Eucalyptus grandis (1250) presented the lowest mortality rates. Therefore, the most recommended clones for the study region were: hybrid of Eucalyptus urophylla x Eucalyptus camaldulensis (VM01),hybrid of Eucalyptus urophylla x Eucalyptus grandis (A217),Eucalyptus platyphylla (373),and hybrid of Eucalyptus urophylla x Eucalyptus grandis (1250) due to their highest values in diameter, height, and lower mortality rate.

Adaptabilidade de clones de eucalipto à inoculação de fungos micorrízicos em solo arenoso em São Domingos do Araguaia PA / Adaptability of eucalyptus clones to the inoculation of mycorrhizal fungi in sand soil in São Domingos do Araguaia PA

Atualmente, as espécies do gênero Eucalyptus figuram nas espécies mais importantes nas plantações florestais comerciais. Estas espécies apresentam dependência de associação micorrízica para o crescimento em condições de campo. Este estudo teve como objetivo avaliar a adaptabilidade de clones de eucalipto sob inoculação de fungos micorrízicos na região de Marabá, sudeste do estado do Pará, Brasil. O experimento foi instalado em delineamento de blocos ao acaso com três repetições, com 12 tratamentos e seis clones. O espaçamento das mudas foi de 3,0 x 3,0 metros, cada parcela com 56 árvores, sendo a metade inoculada com fungos micorrízicos (endomicorrízico e ectomicorrízico). A outra metade das mudas não foi inoculada e funcionou como controle. Cada clone continha 168 indivíduos, totalizando 1008 mudas de clones de eucalipto. A inoculação com isolados micorrízicos não promoveu o maior crescimento em diâmetro e altura dos clones. Os clones: híbrido de Eucalyptus urophylla x Eucalyptus camaldulensis (VM01), de Eucalyptus platyphylla (373) e híbrido de Eucalyptus urophylla x Eucalyptus grandis (1250) apresentaram as menores taxas de mortalidade. Portanto, os clones mais recomendados para a região de estudo foram: híbrido de Eucalyptus urophylla x Eucalyptus camaldulensis (VM01), híbrido de Eucalyptus urophylla x Eucalyptus grandis (A217), Eucalyptus platyphylla (373) e híbrido de Eucalyptus urophylla x Eucalyptus grandis (1250) devido aos seus maiores valores em diâmetro, altura e menor taxa de mortalidade.(AU)

Currently, the species of the genus Eucalyptus figure among the most important species for commercial forest plantations. These species present dependence on mycorrhizal association to grow in field conditions. This study had the objective to evaluate the adaptability of eucalyptus clones under inoculation of mycorrhizal fungi in the Marabá region, southeastern Pará state, Brazil. The experiment was set up in a complete random block design with three replicates, with 12 treatments, and six clones. Seedling spacing was 3.0 x 3.0 meters, each plot with 56 trees, where half of them were inoculated with mycorrhizal fungi (endomycorrhizal and ectomycorrhizal). The other half of the seedlings were not inoculated and worked as control. Each clone had 168 individuals, totalizing 1008 seedlings of eucalyptus clones. Inoculation with mycorrhizal isolates did not promote the highest growth in diameter and height of the clones. The clones: hybrid of Eucalyptus urophylla x Eucalyptus camaldulensis (VM01), Eucalyptus platyphylla (373) and hybrid of Eucalyptus urophylla x Eucalyptus grandis (1250) presented the lowest mortality rates. Therefore, the most recommended clones for the study region were: hybrid of Eucalyptus urophylla x Eucalyptus camaldulensis (VM01),hybrid of Eucalyptus urophylla x Eucalyptus grandis (A217),Eucalyptus platyphylla (373),and hybrid of Eucalyptus urophylla x Eucalyptus grandis (1250) due to their highest values in diameter, height, and lower mortality rate.(AU)

Intercropping Acacia mangium stimulates AMF colonization and soil phosphatase activity in Eucalyptus grandis

Arbuscular mycorrhizal fungi (AMF) are very important to plant nutrition, mostly in terms of acquisition of P and micronutrients. While Acacia mangium is closely associated with AMF throughout the whole cycle, Eucalyptus grandis presents this symbiosis primarily at the seedling stage. The aim of this study was to evaluate the dynamics of AMF in these two tree species in both pure and mixed plantations during the first 20 months after planting. We evaluated the abundance, richness and diversity of AMF spores, the rate of AMF mycorrhizal root colonization, enzymatic activity and soil and litter C, N and P. There was an increase in AMF root colonization of E. grandis when intercropped with A. mangium as well as an increase in the activity of acid and alkaline phosphatase in the presence of leguminous trees. AMF colonization and phosphatase activities were both involved in improvements in P cycling and P nutrition in soil. In addition, P cycling was favored in the intercropped plantation, which showed negative correlation with litter C/N and C/P ratios and positive correlation with soil acid phosphatase activity and soil N and P concentrations. Intercropping A. mangium and E. grandis maximized AMF root colonization of E. grandis and phosphatase activity in the soil, both of which accelerate P cycling and forest performance.

Characterization of Ectomycorrhizal species through molecular biology tools and morphotyping

Mycorrhizae are mutualistic associations between fungi and plant roots. These symbiotic associations are abundant and occur in 75 to 80 % of plants. Ectomycorrhizal fungi are very important in ecosystems, because their mutualistic association with plants of different species helps nutrients and water absorption, as well as protection of the host plant against pathogens and abiotic stresses. Most ectomycorrhizal fungi belong to the Basidiomycota class, such as the following genera: Amanita, Hebeloma, Hysterangium, Laccaria, Lactarius, Rhizopogon, Russula, Scleroderma, Suillus, Tricholoma, among others. Morphological studies on ectomycorrhizae report important results in understanding the species biodiversity. However, the use of molecular biology nowadays is indispensable. Among the various molecular tools available, there is consensus about the use of tools based on sequencing of the Internal Transcribed Spacer (ITS) of fungi rDNA, aiding in species characterization and construction of phylogenetic studies. The ITS region is of easy amplification, it has multicopy nature and enables differentiation between species. The objective of this study was to show that the use of molecular biology tools associated with morphotyping to characterize species of ectomycorrhizae is more effective than when they are used on their own.