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The influence native endophytes have on grass establishment and productivity was evaluated by cocultivating Bouteloua eriopoda (Torr.) Torr. (black grama) or Sporobolus cryptandrus (Torr.) Gray (sand dropseed) seedlings with endophyte-laden calli from three of four native grass and shrub species: Atriplex canescens (Pursh) Nutt. (fourwing saltbush), S. cryptandrus, Sporobolus airoides (Torr.) Torr. (alkali sacaton), and B. eriopoda in vitro. Following cocultivation, grass seedlings were hardened and transferred to three replicate field plots, each containing 16 grass plants of a single species that had been cocultivated with a single callus species. Plant establishment rates, heights, crown diameters, aboveground biomass, seed yields, and seed quality were compared. In B. eriopoda (black grama), significant increases in plant biomass were not observed. However, early plant heights and crown diameters, establishment rates, and stolon production were higher in some callus treatments. In S. cryptandrus (sand dropseed), all variables were positively influenced by one or more of the endophyte treatments. Biomass increases ranged from 2.5-to threefold over untreated plants, and harvested seed increased 5.9-fold in plants treated with endophytes from A. canescens (fourwing saltbush). Seed quality, determined by purity, germination rates, and tetrazolium assays, did not differ across endophyte treatments for either grass. There is evidence that endophyte transfer is responsible for the altered vigor of treated plants. Resumen Se evaluó la influencia que los endófitos nativos tienen en el establecimiento y productividad de los zacates al co-cultivar plántulas de Bouteloua eriopoda (Torr.) Torr. (''black grama'') o Sporobolus cryptandrus (Torr.) Gray (''sand dropseed'') con callos conteniendo de endofitos de tres de cuatro especies nativas de zacates y arbustos: Atriplex canescens (Pursh) Nutt. (''fourwing saltbush''), S. cryptandrus, Sporobolus airoides (Torr.) Torr. (''alkali sacaton'') y B. eriopoda in-vitro. Despue´s del co-cultivo, las plántulas de los zacates fueron aclimatadas y transferidas a campo con tres repeticiones, cada parcela conteniendo 16 plántulas de una especie de zacate, que habían sido co-cultivadas con un callo de una sola especie. Se compararon las tasas de establecimiento, alturas, diámetros de corona, biomasa ae´rea y rendimiento de semilla y su calidad. En B. eriopoda (''black grama'') no se observaron incrementos significativos de la biomasa vegetal. Sin embargo, la altura y diámetro de la corona en etapas tempranas, las tasas de establecimiento y la producción de estolones fueron mayores en algunos de los tratamientos con callos. En S. cryptandrus (''sand dropseed''), todas las variables fueron influenciadas positivamente por uno o mas de los tratamientos de endófitos. Los incrementos de biomasa estuvieron en un rango de 2.5 a 3 veces más de lo producido por las plantas sin tratar y la semilla cosechada fue 5.9 veces más en las plantas tratadas con endofitos provenientes de A. canescens (''four...

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The diatom community was studied in 110 sites within the Guadalquivir River catchment area, South Spain, in order to test the applicability of diatom biotic indices developed in other European regions to this site and to provide a useful tool for monitoring water quality in the river basin. We identified 399 taxa and calculated five diatomic indices (Specific Polluosensitivity Index (IPS), Biological Diatom Index, Trophic Diatom Index, Index of the European Economic Community, and Diatom-based Eutrophication Pollution Index (EPI-D)). Since the indices analyzed were highly correlated, their results could be compared. The indices that gave the best results were the EPI-D followed by the IPS, the latter being the most widely used index in Iberian catchments. Nevertheless, the EPI-D presented certain advantages: (1) this index correlated the best with the water chemistry in the catchment area; (2) EPI-D is not sensitive to the presence of taxa belonging to the Achnanthidium minutissimum complex frequently present in the Guadalquivir basin. Nevertheless, EPI-D retains its effectiveness and thus constitutes an easier index for application from a taxonomical standpoint. We estimated the general water quality of the entire basin on the basis of EPI-D. According to these results, 55% of the sites had either high or good water quality. The species that better characterized each water quality category in the study area were: A. minutissimum (high and good), Amphora pediculus (moderate), Nitzschia frustulum (poor), and Nitzschia capitellata (bad).