Yield Formation in Mediterranean durum wheats under two contrasting water regimes based on path-coefficient analysis

The components of grain yield are altered by adverse growing conditions as the effects of certain environmental factors on crop growth and yield differ depending upon the developmental stages when these conditions occur. Path-coefficient analysis was used to investigate the main processes influencing grain yield and its formation under Mediterranean conditions. Twenty-five durum wheat genotypes, consisting of four Spanish commercial varieties and 21 inbred lines from the ICARDA durum wheat breeding program, were grown during 1997 and 1998 under both rainfed and irrigated conditions in southern Spain. {P}ath-coefficient analysis revealed that under favourable conditions grain yield depended in equal proportion on the three primary yield components (i.e. spikes m⁻², grains spike⁻¹, and mean grain weight), whereas in the rainfed experiments, variations in grain yield were due mainly to spikes m⁻² and to a lesser extent to grains spike⁻¹. Compensatory effects were almost absent under irrigated treatments; however, under water shortage, spikes m⁻² exerted a negative influence on grain spike⁻¹ due mainly to a negative interrelationship between tiller production and apical development. These compensatory effects could partially explain the restricted success in durum wheat breeding observed in water-limited environments of the Mediterranean region. Under rainfed conditions the number of spikes m⁻² depended mainly on the ability for tiller production, whereas in the irrigated experiments the final number of spikes was determined mostly by tiller survival.     

Influence of cropping on the content,composition and dynamics of organic residue in the soil of the plough layer

Organic residue (OR) forms the undecomposed part of soil organic matter (SOM). The majority of it originates from plant remains, but to a certain extent it may also be derived from manure and from the remains of heterotrophic soil organisms. The OR content and dynamics are influenced by management practices (crop rotation, tillage, manuring). The main objective of this work was to study the effect of cropping on the content, fractional composition (coarse and fine fragments) and annual turnover of nonhumified SOM or OR in arable Podzoluvisol in the conditions of south Estonia and to evaluate the role of OR in the humus status of soil. Using the soil-coring method, the OR content and composition and underground phytomass (UGP) as a source of OR in the plough layer were studied. The soil cores (252) were taken during 1991–1992 from three long-term field trials cropped with wheat, barley, rye, potatoes and short-term clover-grass mixtures. The sample plots selected from field trials were tilled conventionally and fertilized according to normal Estonian soil management practice (with a mean rate of N₈₀P₂₃K₄₀ kg ha^-1 year^-1). The average OR content in arable soil ranged from 1.0 to 1.6 g ash-free dry matter (DM_af) kg^-1 soil. The greatest amount of UGP (2.85 g DM_af kg^-1), as a source of OR in soil, was estimated for the 2-year clovergrass mixture. Soil organic carbon accumulated in the composition of OR forms 5.7% of the total organic carbon pool of the plough layer. In regular cropping systems the OR content and pool seem to fluctuate within limits determined by the pedoecological conditions of the soil.     

Genetic Relationship between <Emphasis Type="Italic">Castanea sativa</Emphasis> Mill. Trees from North-western to South Spain Based on Morphological Traits and Isoenzymes

This study is focused in the main chestnut growing areas from north- to south-western Spain. We studied 50 accessions corresponding to 22 cultivars named by local growers; 11 from Andalucía, 9 from Castilla-León, and 2 from Extremadura. These were compared with 22 types classified previously in Galicia (82 accessions). Ten morphological traits and five isoenzyme systems were used to classify them and establish genetic relationships. A lower genetic variability has been found in Extremadura (middle Spain) and Andalucía (south) than in Galicia (north western) which may be because of the lower importance of the crop in those areas and the geographic barriers between them. Galicia could be the origin of the types found in Castilla-León, Extremadura, and south-western Andalucía, and the types found in Central Andalucía were closer to those found in Castilla-León and Extremadura. Most accessions studied (117/132) could be classified positively, making 37 out of 44 cultivars found from northern to southern Spain. Three groups of synonymies were found in Castilla-León: ‘Brava’ and ‘Negral’, ‘Gallego’ and ‘Injerto’, and ‘Rapega’ and ‘Verdello’. Most of the Spanish types have been propagated as a principal clone. Variability within the types is important and must be considered to select the best clones as cultivars.     

Effects of sewage sludge amendment on humic acids and microbiological properties of a semiarid Mediterranean soil

The residual effects of adding 40 t ha^–1 sewage sludge (SL) to a degraded soil cropped with barley were investigated after 9 and 36 months in a field experiment under semiarid conditions. The principal soil properties were apparently still affected by SL amendment 9 months after application but the effects disappeared after 36 months. With respect to control soil humic acids (HAs), the SL-HA was characterized by higher contents of S- and N-containing groups, smaller contents of acidic groups, a prevalent aliphaticity, extended molecular heterogeneity, and smaller degrees of aromatic polycondensation and humification. Amendment with SL caused an increase in N, H, S and aliphaticity contents and a decrease in C/N ratios and O and acidic functional group contents in soil HAs isolated 9 months after SL application. These effects tended to decrease after 36 months, most probably because the slightly humified SL-HA was mineralised over time through extended microbial oxidation, while only the most recalcitrant components such as S-containing and aromatic structures were partially accumulated by incorporation into soil HA. Microbial biomass, basal respiration, metabolic quotient and enzymatic activities increased in soil 9 months after SL application, possibly because of increased soil microbial metabolism and enhanced mineralisation processes. After 36 months these properties returned to values similar to those of the unamended soil, presumably due to the loss of energy sources.     

Bovine blood components: fractionation, composition, and nutritive value

The objective of this research work was to fractionate bovine blood, collected hygienically in a slaughterhouse, into blood plasma protein concentrate, red blood cell concentrate, globin isolate, and a carboxymethylcellulose-heme iron (CMC-heme) complex. All four fractions were studied for proximate composition and amino acid and mineral contents. The nutritive value of plasma protein concentrate and globin isolate was comparatively studied using rat bioassays. The amino acid content in plasma protein concentrate is well balanced and produced net protein utilization and net protein ratio equivalent to 95% those of casein. Globin isolate ( approximately 91% protein) is deficient in isoleucine and S-containing amino acids and was unable to support rat growth at 10% concentration in the diet. Red blood cell concentrate and the isolated CMC-heme complex were good sources of bioavailable iron. Iron availabilities for CMC-heme and whole blood cell concentrate, related to ferrous sulfate as 100%, were 64 and 70%, respectively.     

Spatial patterns of diversity and genetic erosion of traditional cassava (<Emphasis Type="Italic">Manihot esculenta</Emphasis> Crantz) in the Peruvian Amazon: An evaluation of socio-economic and environmental indicators

This study evaluates quantitatively the suitability of the use of site-specific socio-economic and environmental data as indicators to rapidly assess patterns of diversity and genetic erosion risk in cassava. Socio-economic data as well as farmers’ estimation of genetic erosion were collected in the study area, the Ucayali region of the Peruvian Amazon, through interviews with 285 cassava farmers in 50 communities, while diversity was assessed based on agromorphological characterization of 295 cassava accessions. Using multivariate regression analyses, 50 and 45% of the variation in respectively diversity and genetic erosion estimation could be explained by a selected set of socio-economic and environmental indicators. In both regression models four out of the total of 38 variables proved to contribute significantly (at p < 0.10 level). Additionally, the study revealed that farmers are a good direct source of information on the diversity present at community level, which can contribute to the development of methodologies to assess diversity more rapidly. The results of this study are valuable for the development of models to rapidly assess diversity dynamics in large areas.     

Measurement of coupled nitrification-denitrification in paddy fields affected by Terrazole,a nitrification inhibitor

Coupled nitrification-denitrification and potential denitrification were measured as ¹⁵N₂O and ¹⁵N₂ evolution rates in ammonium sulphate-treated rice soils with or without Terrazole [5-ethoxy-3 (trichloromethyl) 1,2,3 Thiadizole] under laboratory and field conditions. The greatest coupled nitrification-denitrification activity was found after drying and rewetting the soil, with maximum values of 322 ng N cm^–2 h^–1 in the laboratory and 90.8 ng N cm^–2 h^–1 in the field. These ¹⁵N₂O + ¹⁵N₂ evolution rates were about 10 times lower than potential denitrification in these soils. These results and the observed decrease in ¹⁵N₂O + ¹⁵N₂ evolution rate in soils treated with Terrazole (60% under laboratory conditions and 52% under field conditions) indicate that denitrification was limited by coupled nitrification-denitrification activity. Oxygen and previous addition of ammonium sulphate appear to control the rate of ¹⁵N₂O + ¹⁵N₂ evolution in ammonium sulphate-fertilised soils.     

The effect of<Emphasis Type="Italic"> Hormogaster elisae</Emphasis> (Hormogastridae) on the abundance of soil Collembola and Acari in laboratory cultures

This microcosm study investigated the effect of Hormogaster elisae on the abundance of soil Collembola and Acari in laboratory cultures. Two types of microcosm were prepared: type I consisted of plastic boxes with a 2-mm mesh cage containing two H. elisae, and type II consisted of plastic boxes without a cage. The respective controls contained no earthworms. All of them were kept at 18°C and 20% moisture for 21 days. After this period of time the microcosms were tested and microarthropods were extracted, identified and counted. In general, more microarthropods were recovered from the soils without earthworms. There were significant differences between the soils with respect to the abundance of Collembola (Isotomidae and Sminthuridae), and Acari (Gamasida and Oribatida). The results suggest that, under the experimental conditions employed, H. elisae reduces the abundance of these groups of microarthropods. This may be due to several reasons. A change in environmental heterogeneity produced by H. elisae is suggested. A possible interspecific relationship between these two groups due to competition or depredation is also discussed.     

Volatile compounds in Spanish, French, and American oak woods after natural seasoning and toasting

The volatile composition (volatile phenols, phenolic aldehydes, furanic compounds, lactones, phenyl ketones, and other related compounds) of Spanish oak heartwood of Quercus robur, Quercus petraea,Quercus pyrenaica, and Quercus faginea was studied by gas chromatography/mass spectrometry, in relation to the processing in barrels cooperage and in relation to the French oak of Quercus robur (Limousin) and Quercus petraea (Allier) and American oak of Quercus alba (Missouri), which are habitually used in cooperage. The volatile composition of seasoned oak woods varied according to individual trees, species, and origins, and the differences were more significant in Spanish species with respect to American species than with respect to French species. The toasting process influenced the volatile composition of wood. It led to high increases in the concentration of volatile phenols, furanic aldehydes, phenyl ketones, and other related structures, but the effect on w-lactones levels depended on species and origin. The volatile composition in Spanish oak species evolved during toasting like in French and American oak, but quantitative differences were found, especially important in American species with respect to European species.     

Volatile compounds in a spanish red wine aged in barrels made of Spanish, French, and American oak wood

A red Rioja wine was aged in barrels made of Spanish oak wood (Quercus robur, Quercus petraea,Quercus pyrenaica, and Quercus faginea) during 21 months. The concentrations of some volatile compounds [syringaldehyde, vanillin, eugenol, maltol, guaiacol, 4-ethylphenol, cis and trans isomers of beta-methyl-gamma-octalactone, 2-furfuraldehyde, 5-methyl-2-furfuraldehyde, 5-(hydroxymethyl)-2-furfuraldehyde, and furfuryl alcohol] were studied in these wines and compared with those of the same wine aged in barrels made from French oak of Q. robur (Limousin, France) and Q. petraea (Allier, France) and American oak of Quercus alba (Missouri). Similar concentrations of these compounds were found in wines aged in Spanish and French oak wood barrels, and significantly different concentrations were found with respect to wines aged in barrels made of American oak wood, indicating a different behavior. Thus, wines with different characteristics were obtained, depending on the kind of wood. Also, the kind of wood had an important influence on sensory characteristics of wine during the aging process. Spanish oak wood from Q. robur, Q. petraea, and Q. pyrenaica can be considered to be suitable for barrel production for quality wines, because a wine aged in barrels made of these Spanish oak woods showed similar and intermediate characteristics to those of the same wine aged in French and American oak woods usually used in cooperage.