Role of asymmetry in competition for light in a model of annual plants

We propose and discuss a model describing dynamics of annual plants competing with their nearest neighbours for sunlight. The effect of the competition determines the size, or equivalently, the biomass of each plant and the number of seeds it produces. At the end of a period (year) plants distribute their seeds over the sites in the Moore neighbourhood and then die. They leave their biomass in the form of litter, which hinders germination of the seeds.We show that the dynamical behaviour depends crucially on two parameters—litter reduction rate and the plants’ growth rate. Larger litter reduction rate and smaller growth rate lead to the population of few plants, producing more biomass than when more smaller plants are present and the litter reduction rate is low and growth rate is high. We show that asymmetry in the competition, which could favour bigger plants, have rather weak effect on the dynamical behaviour. The distribution of the biomass depends on the asymmetry. When larger plants receive much more sunlight than the smaller ones, the latter are quite often eliminated from the neighbourhood. For weaker asymmetry smaller plants could survive, producing however less biomass than the larger plants.     

Gusts within plant canopies are extreme value processes

Plant canopy turbulence is characterised by energetic high-velocity downdrafts (sweeps) and updrafts (ejections) that punctuate otherwise quiescent flow and thereby make the dominant contribution to turbulent transport. It is suggested that this turbulence provides a natural setting for the emergence of extreme value processes. The suggestion is supported by simulation data obtained from Lagrangian probability density function models. Predicted wind speed frequency distributions within the lower portions of plant canopies are consistent with observations and are very well represented by Gumbel (extreme value) distributions. This is interpreted as a signature of strong (maximal) intermittent gusts making the dominant contribution to the turbulence. The findings complement the apparent ubiquity of generalised Gumbel distributions of global quantities in boundary-layer turbulence, equilibrium phase transitions and non-equilibrium models with self-organised criticality. In these examples, however, there are no known direct relationships between the global quantities and extreme value processes. The new findings are interesting from a practical perspective because correct parametrisation of the wind speed frequency distribution is required for the accurate quantification of seed abscission and the removal of pollens and passively released pathogenic spores from plant surfaces.     

Ultrasound-assisted green syntheses of novel pyrimidine derivatives and their comparison with conventional methods

Ultrasound-assisted green syntheses of novel potentially bioactive pyrimidine derivatives have been carried out. The same compounds were obtained by conventional methods of synthesis, and the reaction times and yields of final products obtained by these two methods were compared. It was found that the time of utrasound-promoted reactions was reduced by almost 6–96 times, and their yields were equal or turn out to be greater compared to the traditional approach. The synthesized compounds showed a pronounced stimulating effect on plant growth. The most active derivatives were selected for deeper biological studies and subsequent field trials.     

High-intensity ultrasound-based process strategies for obtaining edible sunflower (Helianthus annuus L.) flour with low-phenolic and high-protein content

The sunflower Helianthus annuus L. represents the 4th largest oilseed cultivated area worldwide. Its balanced amino acid content and low content of antinutrient factors give sunflower protein a good nutritional value. However, it is underexploited as a supplement to human nutrition due to the high content of phenolic compounds that reduce the sensory quality of the product. Thus, this study aimed at obtaining a high protein and low phenolic compound sunflower flour for use in the food industry by designing separation processes with high intensity ultrasound technology. First, sunflower meal, a residue of cold-press oil extraction processing, was defatted using supercritical CO₂ technology. Subsequently, sunflower meal was subjected to different conditions for ultrasound-assisted extraction of phenolic compounds. The effects of solvent composition (water: ethanol) and pH (4 to 12) were investigated using different acoustic energies and continuous and pulsed process approaches. The employed process strategies reduced the oil content of sunflower meal by up to 90% and reduced 83% of the phenolic content. Furthermore, the protein content of sunflower flour was increased up to approximately 72% with respect to sunflower meal. The acoustic cavitation-based processes using the optimized solvent composition were efficient in breaking down the cellular structure of the plant matrix and facilitated the separation of proteins and phenolic compounds, while preserving the functional groups of the product. Therefore, a new ingredient with high protein content and potential application for human food was obtained from the residue of sunflower oil processing using green technologies.