Potencial del hongo endofíto epichloë festucae para la mejora del cesped.

{ESP} Algunas especies de gramíneas forrajeras o cespitosas de importancia económica como Festuca arundinacea, Festuca rubra y Lolium perenne son huéspedes de hongos endofíticos de los géneros Neotyphodiumy Epichloë. Estos hongos tienen la capacidad de infectar las plantas sin inducir síntomas, se transmiten eficientemente por semilla y producen alcaloides tóxicos que pueden afectar a herbívoros que consumen plantas infectadas. Festuca rubra es una gramínea que se cultiva para formar céspedes deportivos y ornamentales. En España lamayoría de las plantas de Festuca rubra en poblaciones naturales están infectadas por el hongo Epichloë festucae. Varios estudios han mostrado que la asociación con Epichloë festucae es beneficiosa para las plantas, cuya tolerancia a situaciones de estrés causado por factores bióticos (herbívoros, hongos patógenos) o abióticos (exceso o deficiencia de nutrientes, sequía) esmayor al estar asociadas a Epichloë festucae. Esta especie fúngica tiene un buen potencial como factor útil para la mejora de variedades de Festuca rubra destinadas a céspedes. El hongo posee características que facilitan la producción industrial de variedades de F. rubra infectadas. Estas variedades podrían ser cultivadas con un coste económico ymedioambiental inferior al de las variedades no infectadas.{ENG} Some economically important turf and forage grasses are hosts of Epichloë and Neotyphodium fungal endophytes. These fungi can asymptomatically infect their plant hosts, are vertically transmitted by seed, and produce toxic alkaloids which are toxic to herbivores. Festuca rubra is cultivated as an sports and ornamental turfgrass. In Spain, about 70% of the plants in wild populations are infected by Epichloë festucae. Several studies have shown that the association with this fungal endophyte is beneficial for the plants whose tolerance to biotic (herbivore and fungal pathogen attack) and abiotic stress (nutrient deficiency or excess, drought) is greater when infected. Epichloë festucae has an important potential as an useful factor for turfgrass cultivar improvement. Large scale production of infected seeds is feasible because of several characteristics of the fungal life cycle. Endophyte infected cultivars are likely to perform better than non infected ones in situations of low maintenance lawns, and to require less economic input for theirmaintenance

Allelopathic potential of invasive Ulmus pumila on understory plant species

In Petriplate bioassay and Pot culture, we studied the allelopathic potential of leaf litter of Siberian elm (Ulmus pumila L.) invasive tree species on the germination and growth of three herbaceous plant native species (Dactylis glomerata L., Trifolium repens L. and Chenopodium album L.) commonly found in riparian understory communities. Two assays were done with leaf litter of U. pumila from riverine ecosystems (i). the effects of aqueous litter extracts in Petri dish assays and (ii). the effect of litter residues in pot experiments. The leaf litter extracts inhibited the radicle growth of D. glomerata and T. repens but did not effect the germination. However in pots, leaf litter inhibited the germination speed of C. album and growth of D. glomerata and T. repens. Our results showed the allelopathic potential of U. pumila litter, which reduced the growth of understory species (T. repens and D. glomerata). In the litter of U. pumila many phenolic compounds (hidroxibenzoic, ferulic, coumaric, protocatechuic, vanillic and rosmarinic acids, and quercetin) were detected.project POII10-0179-4700 of the Junta de Comunidades de Castilla La ManchaPeer reviewe

The symbiosis with the fungal endophyte Epichloe festucae affects the phosphorus content of Festuca rubra.

XLIV Reunión Científica de la Sociedad Española para el Estudio de los Pastos. 10-14 de mayo de 2004, Salamanca (España){ESP}En los pastos de dehesas de Salamanca cerca del 70%. de las plantas de Festuca rubra están permanentemente infectadas por el hongo endofítico Epichloe festucae. Se realizó un experimento de campo en el cual se comparó el contenido de fósforo en cinco líneas de F. rubra, cada una de las cuales estaba compuesta por una versión endofítica y otra no infectada. En plantas en estado vegetativo se detectó un aumento estadísticamente significativo del contenido de P en las plantas infectadas de todas las líneas. Este efecto también se observó en plantas en estado reproductivo, pero en este caso no hubo diferencias tan pronunciadas debidas a la infección. También se ha observado una tendencia a una mayor producción de biomasa por parte de las plantas infectadas por Epichloe festucae.{ENG}In the dehesa grasslands of the province of Salamanca, close to 70% of the Festuca rubra plants are infected by the fungal endophyte Epichloe festucae. An experiment was done to compare the phosphorus content in five half-sib families of Festuca rubra. Each family was composed by an endophyte infected and an endophyte free version of the half-sib plants. In plants in vegetative state, the P content was significantly higher for infected plants in analyses conducted at two different years. During the reproductive state of the plants, a non-significant similar trend was observed. Biomass production was also higherin infected that in non-infected plants.Este trabajo se ha financiado con el proyecto AGL 2002-02766 del Plan Nacional 1 +D. Agradecemos la colaboración de María Romo, Yolanda Arnaiz y Carlos Estévez

Mineral content in semiarid grassland systems affected by community structure and soil characteristics

This work was supported by the European Union project nº 8001-CT90-0021.Mineral element concentrations in plants and their relationships with botanical composition and soil characteristics were analyzed over two consecutive years in herbage samples from semiarid grassland systems (central-western Spain) affected by a topographic gradient. There were not significant differences in the mineral concentration of the plant community between sampling years suggesting that factors other than those related to interannual climatic variation are more important in determining the mineral concentration of plant community in semiarid grasslands. A significant effect of slope position on aboveground biomass production, soil characteristics and plant tissue nutrient contents was found. As compared to the upper and middle zones, the lower zones of slope showed greater aboveground biomass production, a lower proportion of forbs, a higher proportion of grasses, higher concentrations of N, Ca, Mg and Na in botanical groups, and lower concentrations of P and K in botanical components. Stepwise multiple regression analysis showed that most of the variation in N, P, K, Ca, and Mg concentrations in the plant community along the slope can be explained by botanical composition and its specific mineral content. Several soil properties (organic matter, total N, total C, coarse sand) proved to be significantly correlated with the N, Ca, Mg, and Na concentrations of grasses, legumes and forbs, indicating an increase in plant tissue concentrations with increasing eutrophic status in soil from the upper to the lower zones of the slope. The P and K concentrations of legumes and forbs varied according to the phosphorus or potassium contents in soil, which decreased from the upper and middle to the lower zones. The results showed that the mineral concentrations of botanical components were dependent on soil characteristics in different ways.Peer reviewe

Estimation of mineral content in natural grasslands by near infrared reflectance spectroscopy

Near infrared reflectance spectroscopy (NIRS) was tested to predict nitrogen and mineral concentration (N, P, K, Ca, Mg, Na, Mn, Fe, Cu and Zn) in natural grassland samples. The samples were taken from different community types according to the topographic gradient, at different maturation stages and during a period of four consecutive years. A subset of 95 samples was selected on the basis of the spectral variation. Chemical values from the calibratíon sample set were regressed on the corresponding spectral data using a stepwise multiple regression analysís. Another subset of 75 samples was used as the validation set. Standard errors of prediction and correlation coefficients, respectively, were: 0.71 and 0.97 (N), 0.22 and 0.73 (P), 1.83 and 0.84 (K), 0.83 and 0.92 (Ca), 0.15 and 0.92 (Mg), 3.94 and 0.66 (Na), 44 and 0.84 (Mn), 19 and 0.75 (Fe), 1.01 and 0.77 (Cu), 3.9 and 0.79 (Zn).This work was supported by the European Uníon (Contract N 8001-CT90-0021). Thanks are due to L.G. Criado, C. Estévez and M. Hernández for their assistance in the field work.Peer reviewe

Evaluation of alfalfa varieties in the province of Salamanca

XLV Reunión Científica de la SEEP (Sesión: Producción Vegetal)Se realiza un estudio comparativo de 26 variedades registradas de alfalfa (Medicago sativa L.), cultivadas en regadío en la provincia de Salamanca, evaluando la producción y contenido de proteína bruta. El primer año del experimento se realizaron cuatro cortes, siendo la producción en el primer corte significativamente más baja que en el resto. La producción total anual oscila entre 8160 kg ha-1 en la variedad “Baraka” y 10109 kg ha-1 en “Bar MS 82439”, con un valor medio sobre todas las variedades de 9370 kg ha-1. El contenido de proteína bruta oscila entre 19,30% en la variedad “Almar” y 23,47% en la variedad “Aragón”.{ENG}Dry matter production and protein content were evaluated in 26 alfalfa (Medicago sativa L.) varieties grown under irrigation in the province of Salamanca. In the first year four harvests were made. The dry matter production of the first haverst was the lowest. The annual dry matter production ranged between 8160 kg ha-1 in “Baraka” and 10109 kg ha-1 in “Bar MS 82439”, with a mean value across varieties of 9370 kg ha-1. The protein content ranged between 19.30% in “Almar” and 23.47% in “Aragón” variety.Este trabajo ha sido realizado con financiación del Ministerio de Ciencia y Tecnología (AGL2002-02766 AGR-FOR

Infection with the fungal endophyte Epichloë festucae may alter the allelopathic potential of red fescue

16 páginas, 3 tablas, 2 figurasRed fescue (Festuca rubra) is a perennial grass used as both forage and turfgrass. Asymptomatic plants of this species are systemically infected by the fungal endophyte Epichloë festucae, which has a beneficial effect on the infected plants. The aim of this study was to determine the effect of the endophyte Epichloë festucae on the allelopathic potential of Festuca rubra against four associated pasture species that are also considered as weeds in lawns, Trifolium pratense, Trifolium repens, Lotus corniculatus, and Plantago lanceolata. Two experiments were designed to evaluate the allelopathic effect of extracts from the roots and leaves of endophyte-infected (E+) and non-infected (E-) plants on the germination and seedling growth of the four target species. Regardless of the endophyte status of the host plant, leaf extracts elicited a stronger reduction in germination and seedling growth than root extracts. Extracts from E+ plants reduced the speed of germination index of Trifolium spp. to a greater extent than those from E- plants. Radicle length of the target species was the parameter most affected by the presence of the endophyte in F. rubra. Root extracts from E+ plants had a greater inhibitory effect on the radicle growth of the target species than did root extracts from E- plants. A greater concentration in total phenolic compounds was found in the roots of E+ plants than of E-; however, this difference was not observed in the leaves. Thus, the allelopathic potential of F. rubra is altered in infected plants.This work was funded by project AGL2008-01159AGR from the Spanish Ministry of Science and Innovation and FEDER. Thanks are due to Dr. Nuria Pedrol for helpful comments in the experimental design and procedures and to Dr. Iñigo Zabalgogeazcoa for comments that improved the manuscript.Peer reviewe

Decomposition and biological colonization of native and exotic leaf litter in a Central Spain stream

Riparian invasion by exotic trees may lead to changes in the quality of leaf-litter inputs to freshwater ecosystems. Leaflitter inputs are especially important in headwater streams, where aquatic food webs largely depend on the organic matter provided by the terrestrial vegetation. In a headwater stream of Central Spain, North of Guadalajara Province (Tagus basin) we compared the decomposition and biological colonization of leaf litter among two exotic (Ailanthus altissima Mill. Swingle and Robinia pseudoacacia L.) and two native trees (Fraxinus angustifolia Vahl. and Populus alba L.) co-existing in riparian zones. We hypothesized a lower biological colonization of exotic leaves due to organisms have not co-evolved with the exotic trees according to the Novel Weapons Hypothesis (NWH) and, consequently, lower decomposition rates of exotic leaves. To test our hypothesis, litter bags with different mesh sizes (coarse (C) and fine (F)), were used to distinguish between the total and microbial decomposition. The litter bags were placed in the stream and recovered after 2, 20, 39, 62 and 82 days of incubation. After each collection, we assessed the amount of remaining litter, analysed the nitrogen (N) and phosphorous (P) in the litter, identified the macroinvertebrates and quantified the fungal biomass. Consistent with our hypothesis, we found greater fungal biomass buildup on native leaves than on exotic leaves. However, decomposition rates (k) were species-specific, being the ranking in C-bags (A. altissima = F. angustifolia > P. alba > R. pseudoacacia) slightly different than in F-bags (A. altissima > F. angustifolia > P. alba > R. pseudoacacia). The k in both the C-bags and F-bags were correlated with leaf traits, such as lignin, acid detergent fibre (ADF) and lignin:P. There was not a clear effect of the exotic species on macroinvertebrate variables, but the contribution of macroinvertebrates to litter decomposition was lower in exotic litter than in native litter, as shown by a lower ratio between k in C-bags and k in F-bags (kC : kF). Our results supported that invasive species might impact both biological colonization and decomposition rates in stream ecosystems by the addition of different quality leaf litter when compared to native vegetation. The differences in the biological colonization may be explained by the NWH, but differences in the decomposition rates were better explained by litter quality