No abstract

No abstract

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 (qCO 2 ). The organic management led to an increase in all variables with the exception of EE-BRSP and qCO 2 . 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, CO 2 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.

The effect of arbuscular mycorrhizal fungi (AMF) on micropropagated banana plantlets was evaluated during the acclimatization period. Plants were inoculated with Acaulospora scrobiculata, Glomus elarum or Glomus etunicatum. After cultivation in a greenhouse for 3 months, height, leaf area, fresh weight and dry matter of root and shoots, levei of AMF colonization, nutrient levei, photosynthesis and transpiration rate, water potential and stomatal conductance were measured. The number of AMF spores produced in each treatment was also determined. Plantlets inoculated with AMF had greater height, leaf area and fresh weight of shoots and roots, as well as higher rates of photosynthesis and transpiration than controls. Plants inoculated with Glomus were superior in most of the evaluated parameters.

In the Northeast of Brazil, expansion of guava crops has been impaired by Meloidogyne enterolobii that causes root galls, leaf fall and plant death. Considering the fact that arbuscular mycorrhizal Fungi (AMF) improve plant growth giving protection against damages by plant pathogens, this work was carried out to select AMF efficient to increase production of guava seedlings and their tolerance to M. enterolobii. Seedlings of guava were inoculated with 200 spores of Gigaspora albida, Glomus etunicatum or Acaulospora longula and 55 days later with 4,000 eggs of M. enterolobii. The interactions between the AMF and M. enterolobii were assessed by measuring leaf number, aerial dry biomass, CO2 evolution and arbuscular and total mycorrhizal colonization. In general, plant growth was improved by the treatments with A. longula or with G. albida. The presence of the nematode decreased arbuscular colonization and increased general enzymatic activity. Higher dehydrogenase activity occurred with the A. longula treatment and CO2 evolution was higher in the control with the nematode. More spores and higher production of glomalin-related soil proteins were observed in the treatment with G. albida. The numbers of galls, egg masses and eggs were reduced in the presence of A. longula. Inoculation with this fungus benefitted plant growth and decreased nematode reproduction.

The production of inoculum is one of the hindrances in the large scale application of arbuscular mycorrhizal fungi (AMF). The objective of this work was to evaluate the effect of nutrient solutions with or without TrisHCl buffer, on sporulation of AMF. The experiment was carried out in a greenhouse, using a substrate with sand and vermiculite (1:1 v/v). Fifty spores of Gigaspora margarita, Scutellospora heterogama, and Glomus etunicatum were inoculated in Sorghum vulgare (sorghum) or Panicum miliaceum (fodder millet). The substrate received the following nutrient solutions: Hoagland with 3 μM P (S1); Long Ashton II with 15.9 μM P (S2) and Hoagland with 20 μM P (S3), with or without 50 mM of Tris-HCl buffer (pH 6.5); the control treatment, consisting of a soil + sand + vermiculite (2:1:1 v/v) substrate was irrigated with deionized water. Ten weeks after the beginning of the experiment sporulation did not differ in treatments with sorghum. Panicum miliaceum promoted higher sporulation of the AMF than sorghum, and differences among treatments with nutrient solutions were observed. Production of spores of G. margarita and S. heterogama increased significantly after addition of buffer in S1 and S2, while that of G. etunicatum was improved when the substrate was irrigated with S1 + buffer and S3 solutions. Solution S1 + buffer benefited sporulation of the three fungi. However, as observed, each AMF, host, and substrate system should be studied separately for establishment of the most favorable conditions for inoculum production.

A gravioleira, cujos frutos apresentam elevado potencial para exportação, é de fácil adaptação ao Semi-Árido nordestino, e a sua produção, economicamente importante, vem sendo estimulada. O uso de adubos orgânicos associados à inoculação com fungos micorrízicos arbusculares (FMA) pode ser útil na formação de mudas frutíferas, porém o efeito da adição de adubo na simbiose com gravioleira (Annona muricata L. 'Morada') não é conhecido. Foi investigado o efeito de FMA multiplicado em substrato com resíduo orgânico na formação de mudas de gravioleira mantidas em substratos com fertilizante. O delineamento foi inteiramente casualizado, em fatorial de 2×5: 2 substratos (solo sem ou com 10% de vermicomposto) e cinco tratamentos de inoculação (Acaulospora longula Spain & Schenck e Gigaspora albida Schenck & Smith produzidos em substratos com ou sem resíduo orgânico e controle não inoculado), com quatro repetições. Após 102 dias, avaliou-se: massa seca da parte aérea e radicular, altura, diâmetro do caule, taxa de crescimento, produção de esporos de FMA e de glomalina, atividade enzimática do solo, respiração microbiana, colonização micorrízica total, arbuscular e hifálica. Em geral, a inoculação com FMA estimulou o crescimento, mas no tratamento adubado as mudas em simbiose com G. albida não foram beneficiadas pela associação. O uso de vermicomposto estimulou a colonização micorrízica, a respiração microbiana, a atividade enzimática e a produção de glomalina no solo, porém reduziu a esporulação de A. longula. A utilização de FMA e vermicomposto pode constituir alternativa na produção de mudas de gravioleira, pois reduziu à metade o tempo de formação das mudas e pode reduzir em 75% a dose de adubo a ser aplicada. No entanto, a escolha de FMA compatíveis com o hospedeiro é indispensável para garantir respostas positivas. A aplicação conjunta de FMA e adubo orgânico também pode melhorar a qualidade do solo, contribuindo para a produção sustentável de mudas desta e de outras fruteiras.

-(Role of autoctone community of arbuscular mycorrhizal fungi (AMF) on the development of native plant species in revegetated restinga dunes from coastal region of Paraíba State). Association of arbuscular mycorrhizal fungi (AMF) and plant roots constituted one of the most important ways to mitigate the impact of disturbed area. The aim of this work was to characterize the AMF community in the soil from revegetated dune area and to analyze its infl uence on the native plant development. Soils were collected in rainfall season in the revegetated area. Glomalin-related soil protein production (GRSP), glomerospores density and diversity were evaluated. The infl uence of AMF autoctone community was determined for two native plants: Tabebuia roseo-alba (Ridl.) Sandw. (peroba) and Tocoyena selloana Schum. (jenipapo-bravo). Experimental design for each species was completely randomized with 10 replicates, two treatment -native soil (SN) and disinfested native soil (SND) -were tested. Parameters evaluated were: height, shoot diameter, leaf number and area, shoot and root dry mass, nutrient contents, glomerospore density, mycorrhizal colonization and glomalin-related soil protein production (GRSP). In dune revegetated soil was found 1 glomerospore g -1 soil and 1.20 ± 0.04 mg GRSP g -1 soil, and six AMF species were identifi ed. Native soil promoted more development to plant and fungi. Mycorrhizal colonization in peroba was 80% and in jenipapobravo 60%. Then, AMF are present in revegetated area after mining contributing to growth of native plant species studied in greenhouse conditions, suggesting that their performance is affected by arbuscular mycorrhiza symbiosis.Key words -arbuscular mycorrhiza, native plant species, restinga RESUMO -(O papel da comunidade de fungos micorrízicos arbusculares (FMA) autóctones no desenvolvimento de espécies vegetais nativas em área de dunas de restinga revegetadas no litoral do Estado da Paraíba). A simbiose entre fungos micorrízicos arbusculares (FMA) com raízes de plantas vasculares constitui uma das mais importantes formas de mitigar o impacto das áreas pertubadas. O trabalho objetivou caracterizar a comunidade de FMA presente no solo de área de duna revegetada e avaliar sua infl uência sobre o desenvolvimento de espécies nativas. Foi realizada coleta de solo durante o período chuvoso em área revegetada, avaliando-se: produção de proteínas do solo relacionadas à glomalina (PSRG), densidade e diversidade de glomerosporos. A infl uência da comunidade nativa de FMA foi determinada para duas espécies vegetais nativas: Tabebuia roseoalba (Ridl.) Sandw. (peroba) e Tocoyena selloana Schum. (jenipapo-bravo). Para cada espécie foram testados dois tratamentos -solo nativo (SN) e solo nativo desinfestado (SND) -em delineamento inteiramente casualizado com 10 repetições. Ao fi nal foram avaliados: altura, diâmetro do caule, número de folhas, área foliar, biomassa seca e conteúdo de nutrientes nas partes aérea e radicular, densidade de glomerosporos, colonização micorrízica hifálica, ar...