A. García Ciudad

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

Abstract Near infrared reflectance spectroscopy (NIRS) was tested to predict the nitrogen (N) and mineral concentration [for the elements phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), manganese (Mn), iron (Fe), copper (Cu), and zinc (Zn)] in natural grassland samples. The samples wrere 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 calibration sample set were regressed on the corresponding spectral data using a stepwise multiple regression analysis. 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 (Co), and 3.9 and 0.79 ...

Patterns of aboveground herbage production and nutritional quality structure on semiarid grasslands

Abstract Botanical composition, aboveground biomass, protein, fibre content, and dry matter digestibility (DMD) were used as tools for studying the production and nutritional quality in semiarid grasslands. The study was carried out in herbaceous communities from Central‐West of Spain over a period of five consecutive years (1986–1990). The grassland typologies were mainly related to their positions in topographical gradients (slopes) which characterize the regional landscape. The mean values for the production of aboveground biomass in the communities range between 126 and 304 g/m2 which seem fitted with the possibilities of those areas. The botanical composition is different in the two zones of the slope (upper and lower) and it responds to a defined pattern. Vegetation in the lower zones is dominated by grasses and in the upper zones by forbs. The correlation between production and botanical fractions considered (grasses, legumes and forbs) is significant for the grass group. The results show also that...

Use of near infrared reflectance spectroscopy to assess forage quality of a mediterranean shrub

Abstract Shrubs are an important source of food for domestic livestock and wildlife in semiarid areas. This is particularly true during dry periods when forage from natural pastures is scarce and its quality is low. Cytisus multiflorus is a leguminous shrub which is endemic to the Northwestern Iberian peninsula. This species occurs in poor soils and in degraded or marginal areas. The objective of this study was to evaluate the potential of near infrared reflectance spectroscopy (NIRS) to determine quality attributes of Cytisus multiflorus as a forage feed. NIRS calibrations were developed for crude protein, neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin, cellulose, hemicellulose, ash, and organic dry matter digestibility (OMD). The sample population used included different plant parts and plants of different ages, and was collected in the Spanish province of Salamanca. Calibration models were accurate for the prediction of crude protein (r 2 = 0.99; Standard error of prediction (SEP) = 3.8 g kg−1), OMD (r 2 = 0.98; SEP = 15.7 g kg−1), NDF (r 2 = 0.98; SEP = 13.3 g kg−1), ADF (r 2 = 0.94; SEP = 19.1 g kg−1), cellulose (r 2 = 0.96; SEP = 12.2 g kg−1), and ash (r 2 = 0.91; SEP = 1.1 g kg−1). The results of the lignin and hemicellulose calibrations had lower accuracy (r 2 = 0.76; SEP = 7.0 g kg−1 for lignin and r 2 = 0.88; SEP = 13.6 g kg−1 for hemicellulose). The results showed that NIR spectroscopy can be used for the rapid and accurate prediction of quality attributes in samples of the mediterranean shrub Cytisus multiflorus.

Ergovaline levels in cultivars of Festuca arundinacea

This work was funded by the “Junta de Castilla y Leon “ (CSI3/98). Beatriz R. Vazquez de Aldana was supported by a Research Contract from the Spanish “Ministerio de Ciencia y Tecnologia”.

First report of choke disease caused by Epichloë baconii in the grass Agrostis castellana.

Agrostis castellana is common in semiarid natural grasslands of the province of Salamanca, Spain. In this area, plants showing fungal stromata in their stems were observed in July of 2001. These symptoms are typical of choke disease, caused by Epichloë species in several grasses (3). In this disease, external fungal stromata develop around the leaf sheath of the flag leaf during the reproductive cycle of the plant host. As a result, the inflorescence does not emerge. In natural populations of A. castellana, less than 1% of plants showed disease symptoms, and all the stems of infected plants were sterilized by stromata. Intercellular endophytic mycelium was observed by microscopy in stem pith of diseased plants, but not on samples of 30 apparently healthy plants (1). Ergovaline, a fungal alkaloid, was not detected in lyophilized samples of infected plant tissue (2). In a fungal culture obtained from surface-disinfected leaf sheaths of a diseased plant (1), reniform conidia and conidiophores characteristic of the genus Epichloë were observed (4). To determine the fungal species, the nucleotide sequence of the ITS1-5.8SrRNA-ITS2 region and the three first introns of the beta-tubulin gene were obtained (EMBL Accession Nos. AJ490938 and AJ490939). When compared to those of other Epichloë species, these sequences identified the fungus from A. castellana as E. baconii (3). This fungus has been previously described as a pathogenic fungal endophyte in other Agrostis and Calamagrostis species (3,4). The fact that all stems of infected plants were diseased, infection incidence was low, and no alkaloids were detected in plants suggests that this grass-endophyte interaction is pathogenic and not mixed or mutualistic. References: (1) E. Clark et al. J. Microbiol. Methods 1:149, 1983. (2) N. Hill et al. Crop Sci. 33:331, 1993. (3) A. Leuchtmann et al. Mycol. Res. 102:1169, 1998. (4) J. White Jr. Mycologia 85:444, 1993.