Palabras-clave: malva blanca, temperatura, potencial osmótico, estrés salino.ABSTRACT -S. bonariensis (white mallow), tolerant to glyphosate, is important for the practice of direct sowing in Argentina. The germinating behavior of the species at different temperature conditions (namely 5, 10, 15, 20, 25, 30, 35, 40, 20/10, 25/15, and 30/20 °C in a 12 hour photoperiod of light); saline stress (0, 30, 50, 70, 90, 130, and 150 mM of sodium chloride solutions); and water stress (0, -0.2, -0.4, -0.6, -0.8, -1.

RESUMEN -El Índice de Agresividad Espacial (IAE) es un parámetro bioecológico que indica las características de la distribución de malezas. No existen antecedentes sobre el tema en el cultivo de algodón. El objetivo de este trabajo fue determinar el IAE para Chenopodium album (CHEAL) y relacionarlo con las pérdidas de rendimiento. Se trabajó durante la campaña 2007-2008 en el Campo Experimental de la EEA INTA Santiago del Estero, con el cultivar Guazuncho-INTA. Para el cálculo del IAE, se utilizó un modelo que emplea: altura de planta sobresaliente, su biomasa seca y superficie infestada; número de descendientes, biomasa seca y altura media de los mismos. Dentro del cultivo, en 200 m 2 , fueron marcadas 10 áreas de 1 m 2 . Se realizaron análisis estadísticos paramétricos, ANOVA y Tukey (0,05). Los resultados fueron: a) Algodón: peso de parcela medio: 105.000 g; peso por planta: 597 g; el total de plantas: 79,30; altura media: 0,5951 m; rendimiento medio: 2592 kg ha -1 y, b) CHEAL: peso por parcela: 4920 g; n o de plantas por parcela media: 18,7; altura media: 2,72 m; altura de planta madre de maleza: 3,45 m; 187 plantas hijas, medias con 2,40 m de altura y 58 g de biomasa seca, en la parcela de la planta sobresaliente. El rendimiento de algodón fue de 2.329,50 kg ha -1 en el testigo y las pérdidas medias fueron de 89,76%. El IAE obtenido fue de 3,76 (bajo-intermedio) e indica que, en la distribución, actúan numerosas plantas que se desarrollan en torno a una maleza principal. Con un menor IAE, son mayores las pérdidas producidas en el cultivo de algodón.Palabras-clave: CHEAL, distribución, malezas, modelo, rendimiento.ABSTRACT -The Space Aggressiveness Index (SAI) is a bio-ecological parameter that depicts weed distribution characteristics. There are not antecedents about this subject in cotton crop. This paper was aimed at determining the space aggressiveness index for Chenopodium album (CHEAL) and relating it to yield losses. Work was done on the Guazuncho-INTA cultivar throughout the 2007-2008 campaign in La Maria Experimental Field, EEA INTA Santiago del Estero. To compute the space aggressiveness index a model that includes the outstanding height, dry biomass, and infected area of the individual plant together with the quantity, dry biomass and average height of the offspring was used. The 200 sq m cropland was divided into ten plots and parametric statistical analyses, ANOVA, and Tukey test (0,05) were made. As to the the results obtained were: a) Cotton: -average weight per plot: 105.000 g; -weight per plant: 597 g; total number of plants: 79,30; average height: 0,59 m; average yield: 2,592 kg ha 1 and, b) CHEAL: weight per plot: 4,290 g; average number of individuals per plot: 18,7; average height: 2,72 m; parent plant height: 3,45 m whereas for the offspring the figures were: 187 individuals; average height: 2,40 m; average dry matter: 58 g in plot of surpassing plant. Cotton yield was 2,329,50 kg ha -1 and crop losses were of 89,76%. The space aggressiveness index obtained was that of 3,76 (i.e. low-in...

The occurrence of interspecific hybridization is not the only requirement for gene transfer from a crop to a wild relative. Both crop and wild chromosomes must pair and recombine during meiosis and recombined sequences must be incorporated into the wild genome by subsequent backcrossing. The purpose of this memory is to analyze some of the main processes responsible of the success of gene transfer between related species.It has focused in the case of crop wheat, one of the most important cultivated species at world level, and some of its wild relatives.To evaluate extraspecific transfer from wheat, Triticum turgidum×Aegilops and Triticum aestivum×Aegilops hybrids have been obtained. Several species belonging to the genus Aegilops are the most widespread among the closest wheat relatives in the mediterranean basin, therefore they are prone to gene introgression from crop wheat by natural hybridization. These species are: Aegilops geniculata, Ae. cylindrica , Ae. neglecta, Ae. triuncialis and Ae. ventricosa.Genomic in situ hybridization (GISH) has proven to be very useful for discrimination of parental genomes in interspecific hybrids and derivatives, and it is being routinely used in many polyploid complexes. When used for the analysis of Metaphase-I associations in interspecific hybrids, GISH reveals the outcome of synapsis and crossing-over between the constituent genomes. Metaphase-I pairing of different Triticum×Aegilops hybrids has been analyzed by in situ hybridization experiments that combined both total genomic DNA probes and repeated DNA probes, namely, pAs1 from Ae. tauchii and ribosomal pTa71 probe. As a result, discrimination was increased so it has been possible to analyze the homoeologous pairing level and pattern at Metaphase-I for some chromosome regions. Metaphase-I pairing level has been variable and mainly dependent on wheat parent, though there must be some other factors, genotypic or not, affecting the pairing level. The pattern of homoeologous Metaphase-I association was consistent in different genotypes of each hybrid combination and also in different wheat×Aegilops combinations. GISH has revealed that wheat-Aegilops pairing has exceeded 60% of the whole pairing amount. On average, A genome sequences are much more likely to be