Multivariate analysis approach to evaluate a germplasm collection of Hedysarum coronarium L.

Autochthonous germplasm collected in Spain (Ca´diz and Baleares provinces), Italian ecotypes and cultivated material supplied by a commercial firm were analysed by using a multivariate approach applied to a set of morphological traits. According to these analyses the cultivated material could clearly be separated from the autochthonous germplasm. Variation was observed among the traits studied; Principal Stem Diameter, Leaf Area at Flowering and Susceptibility to Oidium were the main traits in grouping and separating sulla (Hedysarum coronarium L.) entries. A new ecotype (Tarifa) could be used in plant breeding as being a source of resistance to Oidium. The multivariate approach appears to be a valid system for germplasm evaluation in sulla with a higher discriminant capacity than multiple single trait analysis.     

Correction to: Thermal biology of Tuta absoluta: demographic parameters and facultative diapause

Journal of Pest Science - Formula, Equation 2 and the table 3 are published incorrectly in the original publication of the article. The correct version of the article is given below     

Genetic variance components and genetic effects among eleven diverse upland cotton lines and their F2 hybrids

Selecting high yielding upland cotton, Gossypium hirsutum L. lines with improved fiber quality is a primary breeding goal. A diverse set of ten cultivars and one breeding line were crossed in a half diallel. Parents and F₂ hybrids were grown in three environments at Mississippi State, MS. Ten agronomic and fiber traits were analyzed by a mixed linear model approach based on the additive-dominance genetic model. Variance component, genetic effects and genetic correlations were calculated. ‘Acala Ultima’ was a desirable general combiner for fiber length, uniformity, strength, micronaire, lint percentage, and boll weight. ‘FiberMax 966’ was a desirable general combiner for fiber length, uniformity, strength, and all agronomic traits. ‘Tamcot Pyramid’ and M240 were poor general combiners for both fiber and agronomic traits. ‘Coker 315’ was a good general combiner for fiber length, uniformity, micronaire, boll weight, boll number, and yield. Heterozygous dominance effects were associated with several crosses, which suggest their use as hybrids.     

Root growth and phosphorus uptake in wide‐ and narrow‐row soybeans

Most of the research comparing the effect of different row spacing on seed yield in soybeans [Glycine max (L.) Merr.] has been focused on row spacing effects on aboveground crop characteristics such as leaf area, right interception, pod number, or biomass accumulation and their relationships with seed yield. Little work has been done on the effects of narrow‐row spacing on root distribution. Plant distribution may also affect root distribution and interroot competition, and therefore, exploration and use of soil resources. A field experiment was carried out on the Pampas (Argentina) to determine the effect of narrow‐row spacing on root distribution within the topsoil in soybean, and whether different root distributions affect phosphorus uptake. In December 1993, soybeans were planted at two row spacings, narrow rows (0.35 m) and wide rows (0.70 m). Root density was measured during seed filling (92 days after planting) at several points within the inter‐row space down to a soil depth of 30 cm. Aboveground biomass was harvested at maturity and phosphorus (P) uptake was measured. Below the row line, narrow‐row soybeans showed a greater root density than the wide row treatment at 5–10 cm depth, while roots of the wide‐row soybeans had more lateral growth. Root density at both sides of the row down to a depth of 5 cm was greater for the wide‐row treatment. Average root density for each depth for a section of 70 cm wide across the row line indicated there was no significant difference between treatments at any depth. The fewer number of rows for the wide‐row spacing was compensated by a greater lateral extension of roots within the interrow space. This compensation resulted in a similar root density at each depth for both planting patterns, narrow and wide rows. Aboveground biomass and phosphorus concentration in plant tissue at maturity were not affected by row spacing. A similar phosphorus uptake for both treatments was consistent with the lack of effect of the different plant distribution on soil exploration by roots and on aboveground biomass accumulation.     

Modelling start of oak pollen season in different climatic zones in Spain

Quercus pollen and meteorological data for several years from eight sites in Spain have been statistically analysed to select the threshold temperature and calculate the mean heat accumulation for predicting the Quercus pollination start in different climatic areas. The growing degree days method, which assumes the daily temperature varies as a sine wave, was used for heat accumulation calculations. Threshold temperatures between 4 and 12 °C were chosen using linear regression equations forced through the origin and their root mean square error (RMSE) of predicted against the observed dates for each observation site. Above the threshold, the average growing degree days (up to 1999) for the studied years was taken as the predictor value. Results showed a relationship between the selected threshold and elevation and a stronger and statistically significant correlation between threshold and yearly mean temperature, for each site. Regression analysis indicated that the selected threshold and the calculated heat accumulation were optimum for most of the localities. The validity of the results was tested using the meteorological data for the year 2000 as independent variable and this confirmed that there were only a few days difference between the predicted and observed day of the first pollen release for most of the studied localities.     

Images of asteroid 21 Lutetia: a remnant planetesimal from the early Solar System

Images obtained by the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) cameras onboard the Rosetta spacecraft reveal that asteroid 21 Lutetia has a complex geology and one of the highest asteroid densities measured so far, 3.4 ± 0.3 grams per cubic centimeter. The north pole region is covered by a thick layer of regolith, which is seen to flow in major landslides associated with albedo variation. Its geologically complex surface, ancient surface age, and high density suggest that Lutetia is most likely a primordial planetesimal. This contrasts with smaller asteroids visited by previous spacecraft, which are probably shattered bodies, fragments of larger parents, or reaccumulated rubble piles.     

Se-enriched mycelia of Pleurotus ostreatus: distribution of selenium in cell walls and cell membranes/cytosol

The incorporation of Se to fungi has been studied, focusing on element distribution among different cellular compartments and, in particular, polysaccharide structures contained in cell walls. Se-enriched mycelia of Pleurotus ostreatus were obtained in submerged cultures. The incorporation of selenium from the growth medium to mycelia was observed with the relative distribution between cytosol plus cell membranes fraction (CCM) and cell walls fraction (CW) of about 44 and 56%, respectively. CCM fractions were analyzed by size exclusion chromatography with on-line UV (280 nm) and ICP-MS detection (80Se). The results obtained showed selenium binding to components of different molecular masses (about 24% of total selenium coeluted with the compounds of molecular mass > 10 kDa). A polysaccharide-containing fraction of mycelia was treated alternatively with Tris-HCl at pH 7.5 or with chitinase. Better solubility and increased contribution of low molecular mass compounds were observed in chitinase extracts (UV detection), confirming the degradation of polysacharides by the enzyme. The total area under the ICP-MS chromatogram of chitinase extract was 2 times higher with respect to the area for Tris-HCl extract. Furthermore, the relative contribution of selenium in the low molecular mass fraction (molecular mass < 1 kDa) in chitinase extract was 72% as compared to 45% in Tris-HCl extract (based on peak area measurements with respect to total area under the chromatogram). The results obtained suggest selenium binding to chitin-containing polysaccharide structures in fungi cell walls.     

The chemical composition of rainfall in a city of Northern Spain

A study was carried out over a period of 4 yr on precipitation in Santander, a coastal city with heavy rainfall in the north of Spain. An increase in acidity was found for the latter period studied, from April 1984 to April 1985, possibly due to a change in the meteorology of the area in this period. The correlations between the ions themselves, and with pollution from SO₂ and suspended particulate matter, as well as possible correlations with meteorological variables were analyzed using a multiple linear regression method. The influence of mid- and long-range transport of pollutants was also analyzed and found to be important when air masses come from highly industrialized zones both in Central Europe and in neighboring Spanish regions, although the contribution of the latter to total acid deposition is less owing to low frequency and the usually low volume of precipitation.