Uided Maaze Tiburcio Cavalcante

Crescimento de mudas de maracujazeiro-doce (Passiflora alata Curtis) associadas a fungos micorrízicos arbusculares (Glomeromycota)

Para determinar o efeito de fungos micorrizicos arbusculares sobre o crescimento de mudas de maracujazeiro-doce foi conduzido, em casa de vegetacao, experimento com delineamento inteiramente casualizado usando cinco tratamentos de inoculacao (200 esporos/planta de Acaulospora longula Spain & Schenck, Gigaspora albida Schenck & Smith, Glomus etunicatum Becker & Gerd., Scutellospora heterogama (Nicol. & Gerd.) Walker & Sanders e controle nao inoculado), com sete repeticoes. A cada 20 dias foram avaliados altura e numero de folhas e ao final do experimento (90 dias): diâmetro do caule, biomassa, area foliar, colonizacao micorrizica e densidade de esporos de FMA na rizosfera. A partir de 70 dias foram evidenciadas diferencas no numero de folhas; aos 90 dias as plantas inoculadas com G. albida apresentaram maior altura que as demais, que nao diferiram significativamente entre si. Plantas associadas com esse fungo apresentaram, em relacao ao controle, incrementos de 2.138% e 1.430% nas biomassas fresca e seca da parte aerea, 1.937% na biomassa fresca da raiz e 2.671% na area foliar. Apesar de nao existir especificidade de hospedeiro na associacao micorrizica arbuscular, apenas G. albida promoveu respostas significativas no maracujazeiro-doce, indicando a existencia de maior compatibilidade funcional entre esses simbiontes.

Produção de mudas de maracujazeiro-doce micorrizadas em solo desinfestado e adubado com fósforo

The objective of this work was to identify the required P dose and efficient arbuscular mycorrhizal fungi (AMF) to promote growth of seedlings of sweet passion fruit. An experiment was carried out at the greenhouse, in a randomized design with a factorial 2x4x4: two soil conditions (disinfected or not), four treatments of inoculation (inoculated or not with Gigaspora albida, Scutellospora heterogama and native AMF from the rhizosphere of sweet passion fruit plants), four doses of available P (Mehlich-1) (8 - natural soil -, 12, 16 and 20 mg dm -3 ), with four replicates. Native AMF promoted growth of seedlings after 30 days of inoculation, while other fungi stimulated plant development after 45 days. Quadratic models indicated maximum values of plant height in soil, with P values estimated between 15.40 and 16.07 mg dm -3 in disinfected soil and 14.85 and 15.60 mg dm -3 in non disinfected soil, obtained in treatments with S. heterogama and G. albida, respectively. Higher spores density and mycorrhizal colonization were observed in treatments with these fungi, comparing with the native AMF. Growth of sweet passion fruit seedlings can be improved by mycorrhization with selected AMF, with reduction of time spent on seedling production.

Fungos endofíticos em Annona spp.: isolamento, caracterização enzimática e promoção do crescimento em mudas de pinha (Annona squamosa L.)

Endophytic isolates of fungi were obtained from leaves, stems and roots of 110 sweetsop and 90 soursop plants from Pernambuco. Twenty-nine isolates were analyzed for production of extracellular enzymes by qualitative assay in Petri dishes containing specific solid media, and for the capacity to promote growth of sweetsop seedlings. These isolates were identified as Acremonium (10.34%), Aspergillus (3.45%), Chaetomium (3.45%), Colletotrichum (10.34%), Cylindrocladium (13.8%), Fusarium (31.03%), Glomerella (3.45%), Nigrospora (6.9%), Penicillium (6.9%) and Phomopsis (10.34%). Nineteen isolates showed lypolytic activity while five showed proteolytic activity; cellulolytic and amylolytic activity were not detected. Eleven isolates of the genera Acremonium (GFR6 and GRR1), Colletotrichum (GFR4 and PFR4), Phomopsis (PFR3 and GCR4), Cylindrocladium (GRR4), Chaetomium (GRR7) and Fusarium (GRR5, PRR1 and PRR6) efficiently improved plant growth. Increase in shoot dry matter of sweetsop seedlings ranged from 23.2 to 32.7%; there was no increase in root dry matter. It is worthy of note that 20 isolates caused significant (P = 0.05) reduction in root dry matter of sweetsop seedlings. In apparently healthy tissues of sweetsop and soursop plants, some fungi promote shoot growth or reduce root growth, while others have no effect on growth of sweetsop seedlings.

Interactions between an arbuscular mycorrhizal fungus (Scutellospora heterogama) and the root-knot nematode (Meloidogyne incognita) on sweet passion fruit (Passiflora alata)

The effects of inoculation of sweet passion fruit plants with the arbuscular mycorrhizal (AM) fungus Scutellospora heterogama on the symptoms produced by Meloidogyne incognita race 1 and its reproduction were evaluated in two greenhouse experiments. In the 1st, the M. incognita (5000 eggs/plant) and S. heterogama (200 spores/plant) inoculations were simultaneous; in the 2nd, the nematodes were inoculated 120 days after the fungal inoculation. In both the experiments, 220 days after AM fungal inoculation, plant growth was stimulated by the fungus. In disinfested soil, control seedlings (without S. heterogama) were intolerant to parasitism of M. incognita, while the growth of mycorrhized seedlings was not affected. Sporulation of S. heterogama was negatively affected by the nematodes that did not impair the colonization. M. incognita did not affect mycorrhizal seedling growth. The establishment of mycorrhiza prior to the nematode infection contributed for the reduction of symptoms severity and reproduction of M. incognita in disinfested soil.

Efeito de fungos micorrízicos arbusculares no crescimento de mudas de Leucaena leucocephala (Lam.) de Wit. em solos de caatinga sob impacto de mineração de cobre

The arbuscular mycorrhizal fungi (AMF) can promote plant tolerance to heavy metals and have been indicated for use in revegetation processes. The effect of native and introduced AMF on the growth of seedlings of Leucaena leucocephala on soils of caatinga biome impacted by copper mining (Mineracao Caraiba, Jaguarari Municipality, Bahia State) was evaluated. The experiment was set up in a complete randomized design, in a 3 × 4 factorial arrangement, considering soil from preserved caatinga and substrates of a site from which the topsoil was removed and a site which received copper waste; and four inoculation treatments (uninoculated control, inoculated with Glomus etunicatum, Acaulospora longula, and a mixture of the two fungi), with five replicates. Independently of the inoculation treatment, the area where the topsoil was removed was more indicated for preparing the seedlings of leucaena, while the soil from the waste site was not suitable for growth of this plant and the establishment of mycorrhizal association. Although infective, G. etunicatum was not efficient in promoting growth of leucaena in the impacted areas, while the native AMF, A. longula and the mixture of fungi contributed to the development of the seedlings.

Uso de fungos micorrízicos arbusculares (FMA) na promoção do crescimento de mudas de pinheira (Annona squamosa L., Annonaceae)

Arbuscular mycorrhizal fungi (AMF) can be used to promote seedling growth of fruit trees, but their effect on sugar apple is not known. We investigated the role of two isolates of AMF (Acaulospora longula and Gigaspora albida) in promoting the growth of sugar apple seedlings. The experimental design was completely randomized with six treatments and four replicates (totaling 24 units): 1) uninoculated control; 2) uninoculated control in fertilized soil; 3) inoculated with A. longula in soil, 4) inoculated with A. longula in fertilized soil, 5) inoculated with G. albida in soil; 6) inoculated with G. albida in fertilized soil. Seedlings with two leaves were inoculated in the region of the roots with soil-inocula with 200 spores of G. albida or A. longula. After 140 days in a greenhouse the height, leaf number, stem diameter, leaf area, fresh and dry weight of shoot and root, root colonization and production of spores were evaluated. The seedlings benefited from G. albida mycorrhiza when grown in unfertilized soil. Mycorrhizal inoculation did not increase the growth of seedlings in soil with vermicompost. The use G. albida is an alternative in the production of sugar apple seedlings, instead of fertilizers.

Interdependência na absorção e redistribuição de fósforo entre planta mãe e filha de bananeira

Although knowledge of the interdependence between banana mother and daughter plants is important to establish adequate management practices, the subject has been little studied in Brazil. An experiment was set up to measure 32P redistribution between mother and daughter plants, grown for 2, 4 and 6 months, with and without P fertilization, applying 32P in the soil. Masses increased until the last harvest, being higher in mothers (1450 g) than in daughters (900 g), without fertilizer effect. Rhizomes had the highest plant biomasses (53-68%) and corm the lowest ones (2-4%), while the opposite occurred with P rates (0.14-0.26 e 0.33-0.54%). At all harvests, there were redistribution between mothers and daughters, and vice versa, but while mothers retained most of their P, although declining with time (95 to 78%); daughters divided their P equally with their mothers, except at the last harvest when they retained more (60%). More 32P was translated to rhizomes and pseudo stems and less to corms, with leaves and roots at intermediate positions. However, 32P concentrations per mass or total P units were higher in the corms. Therefore, mothers and daughters remained interdependent, with ample distribution of the absorbed 32P, although with preference for the corms.