A germination study of herbicide-resistant field poppies in Spain

Field poppy, Papaver rhoeas L., is a very common weed in winter cereals in North-Eastern Spain. Its control is becoming difficult due to expanding herbicide resistance. To control field poppies there are alternative strategies such as non-chemical control that take into account the weed emergence period. However, there is a lack of knowledge of P. rhoeas emergence patterns in semi-arid conditions. Thus, here we conducted pot experiments on the emergence of P. rhoeas. We aimed to describe the emergence period and to quantify the emergence of a susceptible and of a herbicide-resistant P. rhoeas population at two locations in Catalonia, Spain, from 1998 to 2001 and until 2004 at one of them. Therefore, pots containing seeds of both populations were established at the two locations and emergence was recorded monthly. We studied the origin of the population, the sowing location, the effect of cultivation and the sowing year. First, we found that the main emergence peaks in our experiments occurred in autumn, accounting for between 65.7 and 98.5% of the annual emergence from October to December, and only little emergence was recorded in spring. This emergence pattern is different from those found in the literature corresponding to Northern European countries, where in some cases main flushes occur only in autumn, in spring and winter or only in spring. The emergence was mainly affected by cultivation, but the effect of light stimulus was observed several months later. As a consequence, cultivation should be done in early autumn, promoting emergence during the whole autumn and winter so that emerged seedlings can be controlled before sowing a spring crop. Second, most experiments showed that the emergence was significantly higher in the first autumn than in the following seasons, e.g. 4.1% emergence in the first year and only 2.1, 2.3, 0.5 and 0.6% new emergence at one of the locations for the second, third, fourth and fifth years. Thus, after having a severe P. rhoeas infestation causing a big seed rain, emergence should be stimulated by autumn cultivation in the following season and seedlings controlled by trying to deplete the soil seed bank as much as possible. Despite the fact that emergence will be staggered throughout several years and that there was a significant relationship between rainfall and emergence, so that dry years will cause a smaller emergence rate of the weed, these findings define a cultural management strategy to reduce P. rhoeas infestations and to contribute to integrated weed management strategies combining it with other tools.

Cultural control of herbicide-resistant Lolium rigidum Gaud. populations in winter cereal in Northeastern Spain

Lolium rigidum Gaud. is one of the most common weed species in winter cereals in Northeastern Spain. Herbicide resistance has been growing since the mid 90's and exclusive herbicide use is not enough in many cases, so that it is necessary to combine as many control tools as possible. Six field trials have been conducted during the cropping seasons 2001-02, 2002-03 and 2003-04 on winter cereal infested with herbicide resistant L. rigidum in Northeastern Spain testing different cultural control strategies. Sowing delay was conducted at five fields, mouldboard ploughing at four fields, the combination of sowing delay and ploughing at two fields, increasing the cereal sowing density and combined with sowing delay at one field. Sowing delay was confirmed to have an irregular efficacy depending on the L. rigidum emergence during the delay period. In the trials, weed emergence was reduced up to 88% in the best case but there was no effect in two cases. Ploughing had a more constant efficacy and reduced weed emergence between 50 and 80% although stoniness impeded in one occasion a correct soil inversion causing a very low efficacy. Increasing the cereal sowing rate did not reduce the weed population. The combination of the different methods did not increase significantly the individual efficacy, and one method was clearly more effective than the other, depending on the trial. In fields with high L. rigidum density, these methods are not effective enough and need to be combined with other methods, which are discussed in the text.

Annual and seasonal changes in production and composition of grazed clover-grass mixtures in organic farming

Selostus: Alsike-, puna- ja valkoapilan vaikutus laitumen tuottoon luonnonmukaisessa tuotannossa

Growth, production and quality of pineapple in response to herbicide use

In pineapple fields, weed competition is exacerbated by the fact that the crop is small and has a very slow vegetative development. The objective of this study was to determine the effects of herbicides on growth, yield and quality of pineapple, cultivar 'Pérola'. The experimental design was in randomized blocks with four treatments and four replications. Treatments consisted of weeding by hoe and the herbicides diuron; fluazifop-p-butyl and atrazine + S-metolachlor applied in post-emergence. The characteristics evaluated monthly during the vegetative stage were stem diameter, D-leaf length, number of leaves, number of emitted leaves and percentage of natural floral induction. In the reproductive phase, evaluations were made of average fruit weight (g) with and without crown, fruits length and diameter, number of slip, slip-sucker and sucker type seedlings, determination of soluble solids and pH in the pulp. There was no effect of herbicide treatment on the vegetative growth characteristics. Stem diameter increased until 330 days after planting, showing a decrease after this period. The D-leaf grew over time in all treatments, although phytotoxicity symptoms were observed after the first application of herbicides. The traits evaluated on the reproductive phase showed no significant differences in response to treatments. Therefore, the use of diuron fluazifop-p-butyl and atrazine + S-metolachlor did not affect growth, yield and fruit quality of pineapple, cultivar 'Pérola'.

Bose-Fermi mixtures in optical lattices

Using mean field theory, we have studied Bose-Fermi mixtures in a one-dimensional optical lattice in the case of an attractive boson-fermion interaction. We consider that the fermions are in the degenerate regime and that the laser intensities are such that quantum coherence across the condensate is ensured. We discuss the effect of the optical lattice on the critical rotational frequency for vortex line creation in the Bose-Einstein condensate, as well as how it affects the stability of the boson-fermion mixture. A reduction of the critical frequency for nucleating a vortex is observed as the strength of the applied laser is increased. The onset of instability of the mixture occurs for a sizably lower number of fermions in the presence of a deep optical lattice.

Protein loop compaction and the origin of the effect of arginine and glutamic acid mixtures on solubility, stability and transient oligomerization of proteins

Addition of a 50 mM mixture of l-arginine and l-glutamic acid (RE) is extensively used to improve protein solubility and stability, although the origin of the effect is not well understood. We present Small Angle X-ray Scattering (SAXS) and Nuclear Magnetic Resonance (NMR) results showing that RE induces protein compaction by collapsing flexible loops on the protein core. This is suggested to be a general mechanism preventing aggregation and improving resistance to proteases and to originate from the polyelectrolyte nature of RE. Molecular polyelectrolyte mixtures are expected to display long range correlation effects according to dressed interaction site theory. We hypothesize that perturbation of the RE solution by dissolved proteins is proportional to the volume occupied by the protein. As a consequence, loop collapse, minimizing the effective protein volume, is favored in the presence of RE.

A novel set of DIP-STR markers for improved analysis of challenging DNA mixtures.

Currently available molecular biology tools allow forensic scientists to characterize DNA evidence found at crime scenes for a large variety of samples, including those of limited quantity and quality, and achieve high levels of individualization. Yet, standard forensic markers provide limited or no results when applied to mixed DNA samples where the contributors are present in very different proportions (unbalanced DNA mixtures). This becomes an issue mostly for the analysis of trace samples collected on the victim or from touched objects. To this end, we recently proposed an innovative type of genetic marker, named DIP-STR that relies on pairing deletion/insertion polymorphisms (DIP) with standard short tandem repeats (STR). This novel compound marker allows detection of the minor DNA contributor in a DNA mixture of any gender and cellular origin with unprecedented resolution (beyond a DNA ratio of 1:1000). To provide a novel analytical tool useful in practice to common forensic laboratories, this article describes the first set of 10 DIP-STR markers selected according to forensic technical standards. The novel DIP-STR regions are short (between 146 and 271 bp), include only highly polymorphic tri-, tetra- and pentanucleotide tandem repeats and are located on different chromosomes or chromosomal arms to provide statistically independent results. This novel set of DIP-STR can target the amplification of 0.03-0.1 ng of DNA when mixed with a 1000-fold excess of major DNA. DIP-STR relative allele frequencies are estimated based on a survey of 103 Swiss individuals. Finally, this study provides an estimate of the occurrence of informative alleles and a calculation of the corresponding random match probability of the detected minor DIP-STR genotype assessed across 10,506 pairwise conceptual mixtures.

Exploring the relative DNA contribution of first and second object's users on mock touch DNA mixtures

Contact stains recovered at break-in crime scenes are frequently characterized by mixtures of DNA from several persons. Broad knowledge on the relative contribution of DNA left behind by different users overtime is of paramount importance. Such information might help crime investigators to robustly evaluate the possibility of detecting a specific (or known) individual's DNA profile based on the type and history of an object. To address this issue, a contact stain simulation-based protocol was designed. Fourteen volunteers either acting as first or second object's users were recruited. The first user was required to regularly handle/wear 9 different items during an 8-10-day period, whilst the second user for 5, 30 and 120 min, in three independent simulation sessions producing a total of 231 stains. Subsequently, the relative DNA profile contribution of each individual pair was investigated. Preliminary results showed a progressive increase of the percentage contribution of the second user compared to the first. Interestingly, the second user generally became the major DNA contributor when most objects were handled/worn for 120 min, Furthermore, the observation of unexpected additional alleles will then prompt the investigation of indirect DNA transfer events.

On the Rule of Mixtures for Predicting Stress-Softening and Residual Strain Effects in Biological Tissues and Biocompatible Materials

In this work, we use the rule of mixtures to develop an equivalent material model in which the total strain energy density is split into the isotropic part related to the matrix component and the anisotropic energy contribution related to the fiber effects. For the isotropic energy part, we select the amended non-Gaussian strain energy density model, while the energy fiber effects are added by considering the equivalent anisotropic volumetric fraction contribution, as well as the isotropized representation form of the eight-chain energy model that accounts for the material anisotropic effects. Furthermore, our proposed material model uses a phenomenological non-monotonous softening function that predicts stress softening effects and has an energy term, derived from the pseudo-elasticity theory, that accounts for residual strain deformations. The model’s theoretical predictions are compared with experimental data collected from human vaginal tissues, mice skin, poly(glycolide-co-caprolactone) (PGC25 3-0) and polypropylene suture materials and tracheal and brain human tissues. In all cases examined here, our equivalent material model closely follows stress-softening and residual strain effects exhibited by experimental data

Singlet oxygen reactivity in water-rich solvent mixtures

The 3-methylindole (3MI) oxygenation sensitized by psoralen (PSO) has been investigated in 100%, 20% and 5% O2-saturated water/dioxane (H2O/Dx) mixtures. The lowering of the ¹O2* chemical rate when water (k chem∆3MI = 1.4 × 109 M-1 s-1) is replaced by deuterated water (k chem∆3MI = 1.9 × 108 M-1 s-1) suggests that hydrogen abstraction is involved in the rate determining step. A high dependence of the chemical rate constant on water concentration in H2O/Dx mixtures was found showing that water molecules are absolutely essential for the success of the 3MI substrate oxidation by ¹O2* in water-rich solvent mixtures.

Síntese e avaliação da atividade fitotóxica de derivados da α-Santonina

Mixtures of α-Santonin and various solvents were irradiated by either high or low pressure mercury lamps. The photochemical reactions afforded lumisantonin (11) (76% in acetonitrile), (3S,3aS,9bS)-3,6,6-trimethyl-3,3a,4,5-tetrahydronafto[1,2-b]furan-2,7(6H,9bH)dione (12) (100% in acetonitrile), 10α-acetoxy-3-oxo-1,7αH,6,11βH-guaia-4-en-6,12-olide (8) (26% in acetic acid), 10α-hydroxy-3-oxo-1,7αH,6,11βH-guaia-4-en-6,12-olide (10) (32%) and (E)-3-((3S,3aS,7aS)-3-methyl-2-oxo-6-(propan-2-ylidene)hexahydrobenzofuran-7-(7aH)-ylidene)propanoic acid (9) (44%) (in water/ acetic acid 1:1, v/v). Lactone 12 was also prepared by irradiation of lumisantonin in diethyl ether. Lactones 8 and 10 were converted, respectively, into the 10α-acetoxy-3β-hydroxy-1,7αH,6,11βH-guaia-4-en-6,12-olide (13) (87%) and 3β,10α-dihydroxy-1,7αH,6,11βH-guaia-4-en-6,12-olide (14) (75%) by sodium borohydride reduction. The effects of the compounds on the development of radicle of Sorghum bicolor and Cucumis sativus were evaluated.

Reaction mixtures formed by nitrite and selected sulfa-drugs showed mutagenicity in acidic medium

Nitrite, which is present in preserved meat and can be produced in the oral cavity by reduction of nitrate taken from vegetables, could react in stomach with nitrosatable drugs, giving genotoxic-carcinogenic N-nitroso compounds (NOC). The mutagenicity of reaction mixtures formed by sodium nitrite and selected sulfa-drugs (sulfathiazole, HST; phtalylsulfathiazole, PhST; complex Co(II)-sulfathiazole, Co(II)-ST) in acidic medium was evaluated using the Salmonella typhimurium reverse mutation assay (Ames test), with TA98 and TA 100 strains. The reactions were carried out at room temperature, with a mole ratio [nitrite]/[sulfa-drug] > 1. The three reaction mixtures showed mutagenic effects in the considered range.

Rapid and accurate hplc-dad method for the determination of the herbicide bispyribac-sodium in surface water, and its validation

A new method is described for the determination of the herbicide bispyribac-sodium in surface water, especially from river and irrigated rice water samples. The method involves extraction in solid phase and quantification by high performance liquid chromatography with diode array detection (HPLC-DAD). After optimization of the extraction and separation parameters, the method was validated. The method presented average recoveries of 101.3 and 97.7%, under repeatability and intermediate precision conditions, respectively, with adequate precision (RSD from 0.9 to 7.5%). The method was applied for the determination of bispyribac-sodium in surface water samples with a limit of detection of 0.1 μg L-1.

Thermodynamic study of the solubility of sodium naproxen in some ethanol + water mixtures

By using the van't Hoff and Gibbs equations the apparent thermodynamic functions Gibbs energy, enthalpy, and entropy of solution for sodium naproxen in ethanol + water cosolvent mixtures, were evaluated from solubility data determined at temperatures from (278.15 to 308.15) K. The drug solubility was greatest in neat water and lowest in neat ethanol at all the temperatures studied. By means of non-linear enthalpy-entropy compensation analysis, it follows that the dissolution process of this drug in ethanol-rich mixtures is entropy-driven, whereas, in water-rich mixtures the process is enthalpy-driven.

Indomethacin solubility estimation in 1,4-dioxane + water mixtures by the extended hildebrand solubility approach

Extended Hildebrand Solubility Approach (EHSA) was successfully applied to evaluate the solubility of Indomethacin in 1,4-dioxane + water mixtures at 298.15 K. An acceptable correlation-performance of EHSA was found by using a regular polynomial model in order four of the W interaction parameter vs. solubility parameter of the mixtures (overall deviation was 8.9%). Although the mean deviation obtained was similar to that obtained directly by means of an empiric regression of the experimental solubility vs. mixtures solubility parameters, the advantages of EHSA are evident because it requires physicochemical properties easily available for drugs.