Native Arbuscular Mycorrhizal Fungi Promote Plukenetia volubilis Growth and Decrease the Infection Levels of Meloidogyne incognita.

The use of arbuscular mycorrhizal fungi (AMF) offers promising benefits to agriculture in the Amazon regions, where soils are characteristically acidic and nutrient-poor. The purpose of this research was to investigate the potential effects of two recently described species of AMF (Nanoglomus plukenetiae and Rhizoglomus variabile) native to the Peruvian Amazon for improving the plant growth of Plukenetia volubilis (inka nut or sacha inchi) and protecting the roots against soil pathogens. Two assays were simultaneously conducted under greenhouse conditions in Peru. The first focused on evaluating the biofertilizer effect of AMF inoculation, while the second examined the bioprotective effect against the root knot nematode, Meloidogyne incognita. Overall, the results showed that AMF inoculation of P. volubilis seedlings positively improved their development, particularly their biomass, height, and the leaf nutrient contents. When seedlings were exposed to M. incognita, plant growth was also noticeably higher for AMF-inoculated plants than those without AMF inoculation. Nematode reproduction was significantly suppressed by the presence of AMF, in particular R. variabile, and especially when inoculated prior to nematode exposure. The dual AMF inoculation did not necessarily lead to improved crop growth but notably improved P and K leaf contents. The findings provide strong justification for the development of products based on AMF as agro-inputs to catalyze nutrient use and uptake and protect crops against pests and diseases, especially those that are locally adapted to local crops and cropping conditions.

Diversity of leaf endophytic fungi in mangrove plants of Northeast Brazil

With the aim of increasing the knowledge about endophytic fungi, a group of microorganisms with high biotechnological potential and a valuable source of useful metabolites, a survey in leaves of mangrove plants (Avicennia schaueriana, Laguncularia racemosa, and Rhizophora mangle) was performed at the Itamaracá Island, PE, Brazil. Leaves were collected, during two seasons, dry and rainy, superficially sterilized and fragments maintained in Petri dishes with Potato dextrose agar (PDA) at 28º ± 2º C until isolation of the fungi. Fourty taxa were isolated: 25 species representing 19 genera and 15 morphotypes determined as Mycelia sterilia. Leaves of L. racemosa hosted the highest number of colony forming units (CFU) and taxa. Guignardia sp. and Colletotrichum gloeosporioides were the most frequently isolated, while Glomerella cingulata was the only species found in association with the three host plants. The proportional importance of each fungus differed among hosts. The similarity of fungi species between the two seasons reached only 4.2%, and that between the hosts was also low, with the maximum (A. schaueriana x L. racemosa) reaching 24.2%. Sphaerosporium, as well as Chloridium virescens var. virescens, Microsphaeropsis arundinis, Penicillium pinophilum, Periconia cambrensis, Phoma herbarum, P. diachenii, P. obscurans, Sordaria prolifica and Torula elisii are reported for the first time as endophytic in tropical regions.

Soil biochemistry and microbial activity in vineyards under conventional and organic management at Northeast Brazil

The São Francisco Submedium Valley is located at the Brazilian semiarid region and is an important center for irrigated fruit growing. This region is responsible for 97% of the national exportation of table grapes, including seedless grapes. Based on the fact that organic fertilization can improve soil quality, we compared the effects of conventional and organic soil management on microbial activity and mycorrhization of seedless grape crops. We measured glomerospores number, most probable number (MPN) of propagules, richness of arbuscular mycorrhizal fungi (AMF) species, AMF root colonization, EE-BRSP production, carbon microbial biomass (C-MB), microbial respiration, fluorescein diacetate hydrolytic activity (FDA) and metabolic coefficient (qCO2). The organic management led to an increase in all variables with the exception of EE-BRSP and qCO2. Mycorrhizal colonization increased from 4.7% in conventional crops to 15.9% in organic crops. Spore number ranged from 4.1 to 12.4 per 50 g-1 soil in both management systems. The most probable number of AMF propagules increased from 79 cm-3 soil in the conventional system to 110 cm-3 soil in the organic system. Microbial carbon, CO2 emission, and FDA activity were increased by 100 to 200% in the organic crop. Thirteen species of AMF were identified, the majority in the organic cultivation system. Acaulospora excavata, Entrophospora infrequens, Glomus sp.3 and Scutellospora sp. were found only in the organically managed crop. S. gregaria was found only in the conventional crop. Organically managed vineyards increased mycorrhization and general soil microbial activity.

O Vale do Submédio São Francisco é localizado na região do semi-árido brasileiro, sendo um importante centro da fruticultura irrigada, responsável por 97% da exportação nacional de uvas de mesa, incluindo as uvas sem sementes. Baseado no fato de que a fertilização orgânica pode melhorar a qualidade do solo, comparou-se o efeito do manejo orgânico e convencional sobre a atividade microbiana do solo e o estado micotrófico de videiras produtoras de uvas sem sementes. Foi avaliado o número de glomerosporos, número mais provável de propágulos (NMP), riqueza de espécies de fungos micorrízicos arbusculares (FMA), colonização de FMA, produção de PSRG-FE, carbono da biomassa microbiana (C-BM), respiração microbiana, atividade de hidrólise do diacetato de fluoresceína (FDA) e quociente metabólico (qCO2). O manejo orgânico aumentou todas as variáveis, com exceção da PSRG-FE e do qCO2. A colonização micorrízica foi 4.7% no cultivo convencional e 15.9% no orgânico. O número de esporos variou de 4.1 a 12.4 por 50 g-1 solo em ambos os sistemas de manejo. O NMP de propágulos de FMA foi de 79 cm-3 solo no sistema convencional e 110 cm-3 solo no sistema orgânico. O carbono microbiano, a emissão de CO2 e a atividade do FDA apresentaram incrementos de 100 a 200% no cultivo orgânico. Treze espécies de FMA foram identificadas, a maioria no sistema orgânico. Acaulospora excavata, Entrophospora infrequens, Glomus sp.3 e Scutellospora sp. foram registradas apenas na cultura orgânica; S. gregaria foi exclusiva no cultivo convencional. O cultivo orgânico dos parreirais favorece a micorrização e a atividade microbiana do solo.

Soil biochemistry and microbial activity in vineyards under conventional and organic management at Northeast Brazil

The São Francisco Submedium Valley is located at the Brazilian semiarid region and is an important center for irrigated fruit growing. This region is responsible for 97% of the national exportation of table grapes, including seedless grapes. Based on the fact that organic fertilization can improve soil quality, we compared the effects of conventional and organic soil management on microbial activity and mycorrhization of seedless grape crops. We measured glomerospores number, most probable number (MPN) of propagules, richness of arbuscular mycorrhizal fungi (AMF) species, AMF root colonization, EE-BRSP production, carbon microbial biomass (C-MB), microbial respiration, fluorescein diacetate hydrolytic activity (FDA) and metabolic coefficient (qCO2). The organic management led to an increase in all variables with the exception of EE-BRSP and qCO2. Mycorrhizal colonization increased from 4.7% in conventional crops to 15.9% in organic crops. Spore number ranged from 4.1 to 12.4 per 50 g-1 soil in both management systems. The most probable number of AMF propagules increased from 79 cm-3 soil in the conventional system to 110 cm-3 soil in the organic system. Microbial carbon, CO2 emission, and FDA activity were increased by 100 to 200% in the organic crop. Thirteen species of AMF were identified, the majority in the organic cultivation system. Acaulospora excavata, Entrophospora infrequens, Glomus sp.3 and Scutellospora sp. were found only in the organically managed crop. S. gregaria was found only in the conventional crop. Organically managed vineyards increased mycorrhization and general soil microbial activity.

O Vale do Submédio São Francisco é localizado na região do semi-árido brasileiro, sendo um importante centro da fruticultura irrigada, responsável por 97% da exportação nacional de uvas de mesa, incluindo as uvas sem sementes. Baseado no fato de que a fertilização orgânica pode melhorar a qualidade do solo, comparou-se o efeito do manejo orgânico e convencional sobre a atividade microbiana do solo e o estado micotrófico de videiras produtoras de uvas sem sementes. Foi avaliado o número de glomerosporos, número mais provável de propágulos (NMP), riqueza de espécies de fungos micorrízicos arbusculares (FMA), colonização de FMA, produção de PSRG-FE, carbono da biomassa microbiana (C-BM), respiração microbiana, atividade de hidrólise do diacetato de fluoresceína (FDA) e quociente metabólico (qCO2). O manejo orgânico aumentou todas as variáveis, com exceção da PSRG-FE e do qCO2. A colonização micorrízica foi 4.7% no cultivo convencional e 15.9% no orgânico. O número de esporos variou de 4.1 a 12.4 por 50 g-1 solo em ambos os sistemas de manejo. O NMP de propágulos de FMA foi de 79 cm-3 solo no sistema convencional e 110 cm-3 solo no sistema orgânico. O carbono microbiano, a emissão de CO2 e a atividade do FDA apresentaram incrementos de 100 a 200% no cultivo orgânico. Treze espécies de FMA foram identificadas, a maioria no sistema orgânico. Acaulospora excavata, Entrophospora infrequens, Glomus sp.3 e Scutellospora sp. foram registradas apenas na cultura orgânica; S. gregaria foi exclusiva no cultivo convencional. O cultivo orgânico dos parreirais favorece a micorrização e a atividade microbiana do solo.

Production and infectivity of inoculum of arbuscular mycorrhizal fungi multiplied in a substrate supplemented with Tris-HCl buffer

The effect of adding Tris-HCl buffer on production and infectivity of AMF inoculum was investigated. Sporulation of Glomus etunicatum, Acaulospora longula and Gigaspora albida was improved in solution with buffer. The infectivity of G. etunicatum increased after storage, what suggests that the inoculum of this isolate is benefited by storage.

O efeito da adição do tampão Tris-HCl na produção e infectividade de inóculo foi investigado. A esporulação de Glomus etunicatum, Acaulospora longula e Gigaspora albida foi incrementada utilizando solução com tampão. A infectividade de G. etunicatum aumentou após estocagem, sugerindo que o inóculo deste isolado é beneficiado pelo armazenamento.