Herbicide management information is lacking for recently developed turf-type bahiagrass germplasm. The objective of this study was to evaluate the herbicide tolerance of nine experimental bahiagrass genotypes compared to the industry standard ‘Argentine’. The experimental entries included Argentine and ‘Wilmington’ mutants, and wild-type breeding lines. Plants were grown under greenhouse conditions, and 12 herbicides were applied at 1× and 2× labeled rates. Bentazon, bromoxynil, carfentrazone + 2,4-D + MCPP + dicamba, and carfentrazone were classified as safe. Fluroxypyr, halosulfuron, and triclopyr + clopyralid reduced growth >50% when applied at twice the label rate. Fenoxaprop, sulfentrazone + imazethapyr, and thiencarbazone + iodosulfuron + dicamba reduced growth and caused turfgrass injury above an acceptable threshold (≥20%). In general, the Argentine mutants showed greater herbicide injury compared to the Wilmington mutants. However, metsulfuron exceeded the acceptable injury threshold and stopped growth in all the genotypes, Argentine and genotype WT6 were the least injured by this herbicide. The experimental genotype WT6 consistently showed the greatest herbicide tolerance. Except for one genotype (WT4), the experimental genotypes responded similarly or better than Argentine to the tested herbicides, except for metsulfuron.

This paper presents a multidimensional indicator of institutional quality in Argentina for the period 1862-2008. Initially, it describes a set of variables that aim to measure issues related to the legal framework prevailing in Argentina and its implementation, such as changes in the Constitution and the provincial Constitutions, declarations of state of siege and federal interventions, freedom of press, central bank independence. The indicator is then constructed through the principal component analysis.

The results suggest that periods of high institutional quality in Argentina coincided with the most expansion and relative progress. In other words, poor institutional quality would not only be reflected in lower growth rates but also compromises the ability to follow those countries with the best performace.

Introduction. The emergence of P. caerulea L. seeds was studied for the first time, in order to obtain useful information for cultivation of this plant with ornamental, edible and medicinal values. Materials and methods. Different treatments (aril removal, mechanical and chemical scarification and combinations of them) were performed on fresh seeds before sowing. The treatments simulated different paths that the seeds may follow in nature in this ornithochorus species, those which small growers could reproduce before cultivation. Seed emergence was recorded periodically for 16 months in a greenhouse. Seed emergence initial time, percentage and speed were calculated. Results and discussion. Seeds immersed in hydrochloric acid (chemical scarification) did not germinate, but the rest of the treatments were successful. Emergence percentages were low in most of the treatments and speed was slow in all of them. The minimum seed emergence initial time was 25 days. The curve of the accumulated number of seeds emerged followed an oscillating sigmoid pattern. Conclusion. It is suspected that dormancy exists, which will be dealt with in another paper.

This article reports on the ecological preferences of benthic diatoms in relation to pH, conductivity and organic pollution-eutrophication and their tolerance spectrums. Three Pampean streams subjected to different human impacts were studied. The bottom substrate of these streams is mostly composed of slime-clay with low proportions of gravel and sand ; in consequence, the epipelon is the most represented benthic community. Samples were taken seasonally between 1997-1998 at 9 sampling sites. In each sampling station ten sub-samples were collected by pipetting a superficial layer (5-10 mm) of sediment from different places. Physico-chemical parameters were measured. Considering the ranges of pH, conductivity and organic pollution-eutrophicationthe diatom's tolerance spectrums were established. 162 diatom species were identified. More than 50 % of speciesoccurred in sites where the conductivity was lower than 600 µS cm-1. More than 50 % of species had their preference range in sites with moderate organic matter and nutrient content. Diatom species found show defined preferences for organic pollution-eutrophication, but show less consistent responses for conductivity and, particularly, hydrogen ions content.

The life cycle of a brackish-water population of Palaemonetes argentinus, a normally freshwater shrimp from the warm temperateregion of eastern South America, was studied in Mar Chiquita coastal lagoon, Argentina. In 1995, recruitment took placein January, followed by two growth periods, the first at the beginning of summer and the second from the end of winter throughmost of spring. Females reached a larger size than males. Ovigerous females, probably belonging to two cohorts, were foundfrom October 1995 to February 1996, with a maximum number in November (93 %). Their average size and fecundity varied duringthe breeding period. The sex ratio did not significantly differ from 1:1 except in November. Evidence of mature oocytes inthe ovaries was found in ovigerous and postovigerous shrimps, suggesting that they breed twice a year. However, only some femalesof the first cohort produced a second hatch in 1995. The maximum number of undifferentiated embryos carried by a femalewas 250; there was a positive relationship between fecundity and size. Larvae were collected together with adults from Novemberto March. The life history is similar to that described in several freshwater populations. Differences are restricted to chronologicalaspects such as a shorter unimodal breeding period and are probably related to climatic factors, since Mar Chiquita is nearthe southern limit of the geographic range of the species. Data presented here suggest interannual variations in reproductive patternsthat lead, sometimes, to a longer bimodal breeding period.

In Buenos Aires province, the river Samborombón, which is typical of the plain, was sampled monthly during 1986-1987 inresearch carried out both on its physico-chemicalcharacteristics and the communities present - plankton, phytobenthos, zoobenthos -. In this paper the structure and function of phytoplankton and benthic algal communities in the different sections of the river are compared. Both communities have definite limits as their components are not shared and show different strategies. Likewise, the environmental conditions along the river are variable, leading to differences in the planktonic and benthic algae at the locations studied.

The Holotype of Spaniotoma (Smittia) bilobulata Edwards, 1931 : 299, is redescribed and transferred to the genusPseudosmittia (Goetghebuer) Brundin 1956 emended by Saether 1981. Furthermore P. neobilobulata sp.n. is describedand figured. The genus is first recorded in Argentina.