RESUMO Conhecimento sobre as práticas de produção da árvore é essencial para apoiar projetos de restauração florestal, mas é ainda insuficiente para muitas espécies arbóreas. Maytenus boaria é uma árvore neotropical distribuída pelas montanhas temperadas e subtropicais da América do Sul. No centro da Argentina, é majoritariamente restrita nos remanescentes de floresta mais preservados. Tentativas de plantar esta espécie tiveram pouco sucesso devido às dificuldades de produção de mudas e baixa sobrevivência das plântulas. Montamos quatro ensaios com o objetivo de identificar as restrições à produção de mudas e plantio de campo. Sob condições de estufa, avaliamos os tratamentos de (i) pré-germinação e (ii) resposta das plântulas à inoculação com fungos micorrízicos arbusculares (FMA). No campo, nós plantadas mudas de M. boaria, bem como mudas da árvore mais abundante em nosso local de estudo, e avaliamos a (iii) sobrevivência e altura por 10 anos. Finalmente, (iv) nós quantificamos o recrutamento natural em tentativa de determinar o nicho de regeneração da M. boaria. A germinação variou de 13,1 a 29,2% entre os tratamentos. Sementes sem a polpa estratificadas a 5 °C obtiveram a maior germinação (29,2%). Concentração de fósforo na parte aérea das mudas tratadas com FMA foi significativamente maior (45%) do que em mudas não inoculadas. Sobrevivência das mudas de M. boaria foi semelhante ao da árvore mais abundante em nosso local de estudo, mas sua baixa altura sugeriu crescimento limitado. Nós gravamos baixa abundância de plântulas de M. boaria no campo, portanto, não fomos capazes de identificar as características do seu nicho de regeneração. Atividades de reflorestamento devem incluir a retirada da polpa das sementes e estratificação a 5 °C para melhorar a germinação. A capacidade de FMA para melhorar a nutrição deve ser avaliada em condições de campo.

ABSTRACT Knowledge about tree production practices is essential to support forest restoration projects, but is still lacking for many tree species. Maytenus boaria is a neotropical tree distributed across the temperate and subtropical South American mountains. In central Argentina, it is mainly restricted to the most preserved forest remnants. Attempts to plant this species have had little success due to difficulties in seedling production and low seedling survival. We set up four trials aiming to identify the constraints of seedling production and outplanting. Under greenhouse conditions, we evaluated (i) pre-germination treatments and (ii) seedling response to inoculation with arbuscular mycorrhizal fungi (AMF). In the field, we planted M. boaria saplings as well as saplings of the most abundant tree in our study site and recorded (iii) survival and height for 10 years. Finally, (iv) we quantified natural recruitment in an attempt to determine M. boaria regeneration niche. Germination varied from 13.1 to 29.2% among treatments. Depulped seeds stratified at 5 ºC showed the highest germination (29.2%). Shoot phosphorus concentration in AMF-treated seedlings was significantly higher (45%) than in non-inoculated seedlings. Survival of M. boaria saplings was similar to that of the most abundant tree in our study site, but their lower height suggested limited growth. We recorded low abundance of M. boaria seedlings in the field; therefore, we were unable to identify the characteristics of its regeneration niche. Reforestation activities should include seed depulping and stratification at 5 ºC to improve germination. The capacity of AMF to enhance nutrition should be evaluated under field conditions.

The plant-parasitic nematode Nacobbus aberrans is an endoparasite that induces gall formation in the roots and causes severe losses to diverse crops. Some populations of this nematode show preference for certain hosts, revealing the existence of "races/groups" with different behaviour and making nematode management difficult. A possible biological control alternative to reduce the damage caused by this species may be the use of arbuscular mycorrhizal fungi (AMF). In the present work, the effect of Glomus intraradices on tomato plants inoculated with the nematode at transplanting and three weeks later was tested. At 60 days, the following parameters were estimated: percentage of AMF colonization, root and aerial dry weight, number of galls and egg masses, and reproduction factor (RF=final population/initial population) of N. aberrans. AMF colonization was higher in the presence of the nematode. The use of AMF favoured tomato biomass and reduced the number of galls and RF on the plants inoculated with the nematode at transplanting.

The objective of this study was to determine patterns of arbuscular mycorrhizal (AM) colonization of Alnus acuminata Kunth at two natural forests in relation to soil parameters at two different seasons (autumn and spring). The soil parameters studied were field capacity, pH, electrical conductivity, available P, total N and organic matter. The percentage of AM colonization was estimated and correlated to soil properties and to two different seasons. The results indicate that the percentage of AM colonization varied among soil types and was higher in spring than autumn. A significant positive correlation was found between AM colonization and electrical conductivity, organic matter and total Nitrogen. Results of this study provide evidence that AM colonization of A. acuminata can be affected by some soil parameters and seasonality.

El objetivo de este estudio fue determinar el patrón de colonización micorrícico arbuscular (MA) de Alnus acuminata Kunth en dos bosques del Noroeste Argentino, en relación a los parámetros edáficos y en dos estaciones del año (otoño y primavera). Los parámetros edáficos estudiados fueron: capacidad de campo, pH, conductividad eléctrica, fósforo disponible, N total y materia orgánica. Se cuantificó el porcentaje de colonización MA y se lo correlacionó con las variables estudiadas (parámetros edáficos y estaciones). Los resultados indican que el porcentaje de colonización MA varió entre los dos tipos de suelo y las estaciones, siendo mayor en primavera. Se observó correlación positiva significativa entre el porcentaje de colonización MA y la conductividad eléctrica, materia orgánica y N total. Los resultados de este estudio indican que la colonización MA de A. acuminata puede ser afectada por algunos parámetros edáficos y la estacionalidad.