Chickpea (Cicer arietinum L.), one of the most cultivated legumes worldwide, is crucial for the economy of several countries and a valuable source of nutrients. Yields may be severely affected by Ascochyta blight, a disease caused by the fungus Ascochyta rabiei. Molecular and pathological studies have not yet managed to establish its pathogenesis, since it is highly variable. Similarly, much remains to be elucidated about plant defense mechanisms against the pathogen. Further knowledge of these two aspects is fundamental for the development of tools and strategies to protect the crop. This review summarizes up-to-date information on the disease’s pathogenesis, symptomatology, and geographical distribution, as well as on the environmental factors that favor infection, host defense mechanisms, and resistant chickpea genotypes. It also outlines existing practices for integrated blight management.

Sinorhizobium meliloti is a soil bacterium of great agricultural importance because of its ability to fix atmospheric nitrogen in symbiotic association with alfalfa (Medicago sativa) roots. We looked into the involvement of exopolysaccharides (EPS) in its survival when exposed to different environmental stressors, as well as in bacteria–bacteria and bacteria–substrate interactions. The strains used were wild-type Rm8530 and two strains that are defective in the biosynthesis of EPS II: wild-type Rm1021, which has a non-functional expR locus, and mutant Rm8530 expA. Under stress by water deficiency, Rm8530 remained viable and increased in number, whereas Rm1021 and Rm8530 expA did not. These differences could be due to Rm8530′s ability to produce EPS II. Survival experiments under saline stress showed that viability was reduced for Rm1021 but not for Rm8530 or Rm8530 expA, which suggests the existence of some regulating mechanism dependent on a functional expR that is absent in Rm1021. The results of salinity-induced stress assays regarding biofilm-forming capacity (BFC) and autoaggregation indicated the protective role of EPS II. As a whole, our observations demonstrate that EPS play major roles in rhizobacterial survival.

La aplicación de nuevos desafíos conceptuales-metodológicos y pluridisiplinarios han llevado a la necesidad de preparar a los estudiantes en el desarrollo de diversas habilidades para la incorporación de nuevos conceptos o la transformación de los ya existentes. El objetivo de esta investigación ha sido diseñar y desarrollar una propuesta desde el enfoque constructivo de la enseñanza de la Botánica con el fin de favorecer la conceptualización científica en los estudiantes. Este estudio de caso se llevó a cabo en el curso de Botánica Sistemática Agrícola (BSA), del 1° año de la carrera Ingeniería Agronómica. Se desarrolló una propuesta didáctica para potenciar y andamiar los procesos de aprendizaje conceptual de los estudiantes; para su estudio se observaron clases y se administró un cuestionario exploratorio en tres momentos, el cual consistió en plantear una pregunta abierta sobre un concepto clave inicial para conocer la percepción del estudiante al respecto; en nuestro caso la pregunta fue ¿Qué es la Botánica? Los resultados muestran el grado de avance desde la primer instancia a la tercera, en el primer momento se puede apreciar que los estudiantes tienen conocimientos previos no escolarizados con un grado leve de complejidad y precisión, que fue el punto de partida para considerar la evolución y transformación del mismo a través del presente estudio, en el segundo momento se observó la inclusión de algunos conceptos teóricos claves, y finalmente en el tercer momento se muestra en cada caso una definición más completa y compleja, con constructos más sólidos, incluyendo conceptos de Botánica como de otras ciencias afines. La conceptualización científica, dio lugar a un cambio conceptual, y a la superación de la pluridisciplinariedad como obstáculo epistemológico y su génesis en la transformación del concepto.

In this research, the features that characterize the university consultation classes and tertiary institutes have been described. Although these spaces are not within the prescribed curriculum, they do appear in the messages that teachers post on the billboards. Participation in consultation classes is somewhat arbitrary: the days, times and spaces in which they are offered are set by each teacher. The methodology was a multiple case study. Seven teachers from various universities and tertiary institutes of Río Cuarto, Sampacho and Villa Mercedes participated, as well as ten students who attended the consultation classes. The data were collected through non-participant observations and individual and semi-structured interviews. The results show the relevance in the collaborative construction of professional and socio-emotional skills, work autonomy, learning from genuine problems, the construction of identity processes and shared goals. These features, added to the particularities of the teaching methods, the place where the consultation classes are held and the length of time, allow us to think about the complexity that these learning areas go through.

Most of the weeds that emerge in agricultural fields come from the soil seed bank. The changes that occur in it are of vital importance for weed control and generate variations in magnitude and time of emergence. The objective of this work was to characterize the composition and abundance of the soil seed bank in two types of crops under a livestock rotation. The study area is located in "Pozo del Carril" establishment, an experimental field of the Agronomy and Veterinary Medicine Faculty at the National University of Río Cuarto (FAV-UNRC) near La Aguada, Argentina. removal (SR) and with removal (CR). The size of the seed bank, Wealth (S), Specific Diversity (H') and Equity (J') were analyzed, using the washing and sieving method. Depths were analyzed: 0-5 and 5-10 cm. The largest size of the Soil Seed Bank was found in the first 5 cm of the soil for the two treatments analyzed and the highest value was shown by the treatment without removal at that depth, showing how removal has a differential influence on the distribution of the soil and weed seed bank in the ground. Annual-summer species dominated the seed bank in all treatments, with Eleusina indicating the highest contribution. No significant differences were found between wealth, equity and diversity among the farms analyzed. It is concluded that tillage systems influence the vertical distribution of weed seeds in the first 10 cm of the soil and affect the composition and size of the weed seed bank.