Tiempos de Cambio: Repensar América Latina

América Latina está en movimiento. Frente al frágil desarrollo económico de la región, ya son pocos los que ponen en duda el fracaso del neoliberalismo: Pues, lo que más ha crecido durante las últimas décadas no han sido las economías nacionales, sino sobre todo la dependencia del mercado mundial, la pobreza y la desigualdad social. Y para muchos, la última década de la esperanza se ha convertido en una década de desesperanza. Desde hace unos años, también el mapa político de América Latina está cambiando susceptiblemente: Cada vez son más los gobiernos, partidos y movimientos sociales que exigen un cambio de paradigma económico y político, dando nuevamente prioridad a la justicia social, al incremento de la participación y al desarrollo local. Sin embargo, hasta ahora, estas nuevas ideas y prácticas todavía han sido muy poco concretas, divergentes y opuestas, frecuentemente difusas y hasta confusas. Ello es razón suficiente para reflexionar a más profundidad sobre políticas innovadoras más allá del neoliberalismo, más allá del los “tiempos de cambio”. El libro “Tiempos de cambio - Repensar América Latina” del politólogo alemán Hans-Jürgen Burchardt retoma tal desafío y en vez de recetar nuevas panaceas, empieza con un inventario histórico y sobrio. En él se explican y examinan términos que solían ocupar y monopolizar la política de antes, términos que ahora hay que llenar con nuevos contenidos. Algunos de ellos se refieren a los temas más importantes de nuestro futuro: globalización, Estado, democracia, sociedad civil, descentralización, pobreza y justicia social, y relaciones entre el Norte rico y el Sur pobre. Se trata de problemas y soluciones entre ayer y mañana, entre desarrollos probables y alternativas posibles. Pero no se ofrecen respuestas simplistas, y tampoco se pretende convencer de un paradigma único. Se trata más bien de estimular discusiones y debates, indispensables para encontrar alternativas prometedoras para el futuro. Hoy en día, las perspectivas de América Latina ya no se encuentran fuera del continente. Han sido demasiadas las ocasiones en las que los conceptos y estrategias de otros han llevado al fracaso. Por ende, lo más importante ahora es aprender de las experiencias y errores, fortalezas y debilidades propios, en vez de volver a seguir a las propuestas ajenas. Por lo tanto, el trasfondo de las reflexiones aquí presentadas siempre es América Latina. Debido a esto se proporcionan respuestas claras a la pregunta si la política de Cuba o la Revolución bolivariana de Venezuela contiene elementos de un modelo para el futuro que pueda indicar un camino a seguir. Los nuevos “tiempos de cambio” brindan múltiples oportunidades de acción, pero al mismo tiempo requieren conocimientos sobre las realidad y las opciones existentes. El libro de Burchardt ayuda a desarrollar una posición propia en la creciente complejidad de nuestros tiempos. Invita a participar de manera activa y competente en la creación de una política innovadora de la región y a la vez a reinventar América Latina.

Studies on arbuscular mycorrhiza (AM) in the Alentejo (Portugal) using pea mutants resistant to AM fungi as a control tool for field conditions

The utilization and management of arbuscular mycorrhiza (AM) symbiosis may improve production and sustainability of the cropping system. For this purpose, native AM fungi (AMF) were sought and tested for their efficiency to increase plant growth by enhanced P uptake and by alleviation of drought stress. Pot experiments with safflower (Carthamus tinctorius) and pea (Pisum sativum) in five soils (mostly sandy loamy Luvisols) and field experiments with peas were carried out during three years at four different sites. Host plants were grown in heated soils inoculated with AMF or the respective heat sterilized inoculum. In the case of peas, mutants resistant to AMF colonization were used as non-mycorrhizal controls. The mycorrhizal impact on yields and its components, transpiration, and P and N uptake was studied in several experiments, partly under varying P and N levels and water supply. Screening of native AMF by most probable number bioassays was not very meaningful. Soil monoliths were placed in the open to simulate field conditions. Inoculation with a native AMF mix improved grain yield, shoot and leaf growth variables as compared to control. Exposed to drought, higher soil water depletion of mycorrhizal plants resulted in a haying-off effect. The growth response to this inoculum could not be significantly reproduced in a subsequent open air pot experiment at two levels of irrigation and P fertilization, however, safflower grew better at higher P and water supply by multiples. The water use efficiency concerning biomass was improved by the AMF inoculum in the two experiments. Transpiration rates were not significantly affected by AM but as a tendency were higher in non-mycorrhizal safflower. A fundamental methodological problem in mycorrhiza field research is providing an appropriate (negative) control for the experimental factor arbuscular mycorrhiza. Soil sterilization or fungicide treatment have undesirable side effects in field and greenhouse settings. Furthermore, artificial rooting, temperature and light conditions in pot experiments may interfere with the interpretation of mycorrhiza effects. Therefore, the myc- pea mutant P2 was tested as a non-mycorrhizal control in a bioassay to evaluate AMF under field conditions in comparison to the symbiotic isogenetic wild type of var. FRISSON as a new integrative approach. However, mutant P2 is also of nod- phenotype and therefore unable to fix N2. A 3-factorial experiment was carried out in a climate chamber at high NPK fertilization to examine the two isolines under non-symbiotic and symbiotic conditions. P2 achieved the same (or higher) biomass as wild type both under good and poor water supply. However, inoculation with the AMF Glomus manihot did not improve plant growth. Differences of grain and straw yields in field trials were large (up to 80 per cent) between those isogenetic pea lines mainly due to higher P uptake under P and water limited conditions. The lacking N2 fixation in mutants was compensated for by high mineral N supply as indicated by the high N status of the pea mutant plants. This finding was corroborated by the results of a major field experiment at three sites with two levels of N fertilization. The higher N rate did not affect grain or straw yields of the non-fixing mutants. Very efficient AMF were detected in a Ferric Luvisol on pasture land as revealed by yield levels of the evaluation crop and by functional vital staining of highly colonized roots. Generally, levels of grain yield were low, at between 40 and 980 kg ha-1. An additional pot trial was carried out to elucidate the strong mycorrhizal effect in the Ferric Luvisol. A triplication of the plant equivalent field P fertilization was necessary to compensate for the mycorrhizal benefit which was with five times higher grain yield very similar to that found in the field experiment. However, the yield differences between the two isolines were not always plausible as the evaluation variable because they were also found in (small) field test trials with apparently sufficient P and N supply and in a soil of almost no AMF potential. This similarly occurred for pea lines of var. SPARKLE and its non-fixing mycorrhizal (E135) and non-symbiotic (R25) isomutants, which were tested in order to exclude experimentally undesirable benefits by N2 fixation. In contrast to var. FRISSON, SPARKLE was not a suitable variety for Mediterranean field conditions. This raises suspicion putative genetic defects other than symbiotic ones may be effective under field conditions, which would conflict with the concept of an appropriate control. It was concluded that AMF resistant plants may help to overcome fundamental problems of present research on arbuscular mycorrhiza, but may create new ones.