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The occurrence in Scotland of arbuscular mycorrhizal fungi (AMF) infective on Alnus glutinosa and the effects on early growth of inoculation of seedlings with AMF and Frankia were investigated. AMF characteristic of G/omiw-like fungi were detected microscopically in A. glutinosa roots from mineral and loam but not from highly organic soils. Both GJomus- and Gigaspora-like fungi were detected only in roots from sandy soils. Glasshouse experiments showed that Glomus and Gigaspora species gave higher colonisation of roots, and were of higher compatibility with the host plant, than Acutelospora or Scutettospora species. Colonisation by AMF increased nodulation by Frankia and vice versa. Inoculation with AMF alone and dual inoculation with Gigaspora rosea and Frankia inhibited growth of young A. glutinosa seedlings. Initially after inoculation, AMF colonisation was poor allowing the host to meet the requirements of both developing symbioses. Mycorrhizal plants inoculated with Frankia 15 days after AMF inoculation, were under significant stress and this delayed the beneficial effects of AMF and Frankia symbiosis. Seedlings compensated for the cost of symbiosis by developing a larger, leafy shoot in a period of 25-30 days after AMF inoculation, with or with out, Frankia nodulation. A significant increase in root length and branching detected after inoculation with AMF and Frankia must impose additional energy requirements. However, the stimulation of lateral root branching that follows AMF colonisation may facilitate nutrient uptake, thus helping the plant to overcome the disadvantages of early retardation of shoot growth. Competition with adjacent plant species for below ground space may also be enhanced thus facilitating competition for growing space with other plant species. These factors may be part of a strategy that assists the survival of very young seedlings in the field. The data obtained suggest that delaying Frankia inoculation for 3-4 weeks after inoculation with selected AMF should improve the production in Scottish nurseries of robust, well nodulated and mycorrhizal seedlings.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The Leucaena is a tree specie that it is able to improve the soil and can give food for animals. It is an alternative to farmer in dry periods in Northest. Seeds of leucaena (Leucaena leucocephala Lam) from two populations (Reserva Florestal Ibura and Campus da Universidade Federal de Sergipe), were collected and storage for different periods as goal their utilization as alternative culture aiming agroecosystem sustainability. The objective of this work was to evaluate the physiological and sanitary seed quality and fungi infection to seedlings obtained of seeds storage for 2, 28 and 48 months. The seeds were storage in paper bags inside a refrigerated chamber with 40% of humidity at 10 ± 1° C and the experiments carried out in Phytosanitary Clinical, Tissues Culture and Vegetal Breeding Laboratory and Seeds Laboratory of Universidade Federal de Sergipe from February through December, 2005. It was used a statistical totally randomized design with four replications. It was detected in batches of 48 and 28 months fungi from Aspergillus and Penicillium genus. For seeds storage for 2 months it was detected Pestalotiopsis, Fusarium and Curvularia genus. In concerned to infection of the fungi it was verified the Aspergillus was able to cause hypocotyls necrosis on seedlings. For seeds physiological analysis tests as Germination Speed Index (IVG), Emergence Speed Index (IVE), Electrical Conductivity (CE), Accelerate Ageing (EA), Humidity (%U) and isozymes were carried out. It was verified the seeds storage for two months presented higher values of IVG. In the CE test the seeds storage for two months and submitted to accelerate ageing during 24 hours presented the higher values of CE. The isozyme markers showed alteration in patterns of bands intensity and absence of alteration in protein subunit which permit to infer the batches besides from different provenances, probably were not genetically divergent. This fact corroborates to justify the comparison made in this work. It was observed a decreasing in values of germination with increasing storage periods which suggest vigor lost. It was recommended the storage the leucaena seeds for a period maximum of two years for the conditions of present work. / A leucena (Leucaena leucocephala Lam.) é uma espécie arbórea, capaz de contribuir para o melhoramento do solo, além de servir de forragem para o gado, possibilitando ao agricultor uma alternativa para as regiões áridas do Nordeste. É uma espécie bem adaptada às regiões secas, conseguindo se manter verde por grande parte do ano. Sementes de leucena provenientes de duas populações (Reserva Florestal Ibura e Campus da Universidade Federal de Sergipe) foram coletadas e armazenadas em diferentes épocas do ano visando a sua utilização como alternativa para a sustentabilidade de agroecossistemas. O objetivo do presente trabalho foi avaliar a qualidade fisiológica e sanitária e a transmissão de fungos associados às sementes armazenadas por 2, 28 e 48 meses em sacos de papel dentro de câmara fria com 40% de umidade a 10 ± 1° C. Os experimentos foram realizados na Clínica Fitossanitária, no Laboratório de Biotecnologia e Cultura de tecidos e no Laboratório de Sementes da Universidade Federal de Sergipe, no período compreendido entre fevereiro e dezembro de 2005. Para a análise fisiológica das sementes, empregou-se o delineamento inteiramente casualizado com 4 repetições e as sementes testadas foram previamente submetidas ao envelhecimento acelerado. Testes como Índice de Velocidade de Germinação (IVG), Índice de Velocidade de Emergência (IVE), Condutividade Elétrica (CE), Envelhecimento Acelerado (EA), Grau de Umidade (%U) e isoenzimas foram realizados. No teste de sanidade, nos lotes de 28 e 48 meses de armazenamento, fungos dos gêneros Aspergillus e Penicillium foram detectados Já nas sementes do lote de 2 meses de armazenamento, gêneros como Pestalotiopsis, Fusarium e Curvularia foram detectados e observou-se uma maior diversidade de gêneros fúngicos neste lote do que nos demais. Não foi verificada transmissão de fungos das sementes para as plântulas. Na análise fisiológica, verificou-se para as sementes armazenadas por 2 meses os maiores valores de IVG. No teste de CE as sementes com 2 meses de armazenamento submetidas ao EA por 24 horas apresentaram maiores valores. As análises usando marcadores isoenzimáticos mostraram alterações na intensidade de bandas dos perfis eletroforéticos e ausência de alterações nas subunidades protéicas, o que permite inferir que os lotes, apesar de serem de procedências diferentes, provavelmente não são geneticamente divergentes, o que pode justificar as comparações realizadas no presente trabalho. Observou-se, ainda, uma queda nos valores de germinação com o aumento nos períodos de armazenamento, sugerindo uma perda no vigor.