Vermiculite in Fluidized Bed as Decontaminating Agent for Liquid Phases

Over the last decades, removal of potentially toxic and hazardous materials has received a great deal of attention in the field of environmental pollution. Problems associated with the disposal of the wastes of different kinds of industries led to studies of the sorption?Cuptake properties of clay minerals and zeolites. In the present research, the behavior of vermiculite particles ranging between 425 and 500???m in a laboratory-scale fluidized bed column for uptake of Cs, Hg, and Mn ions from aqueous solutions and wastes in the presence of competing cations has been studied in order to investigate techniques for decontamination of liquid phases. Vermiculite selectively removed high percentages of Cs even from low concentrations in the presence of competing cations. Also removed were up to 60?% of added Hg²⁺ at concentrations of 5?ppm from drinking water and about 84?% from seawater, and furthermore, Mn²⁺ was selectively removed from low-concentration (ca 10?ppm) industrial wastes even when the ratio of Mn²⁺ to competing cations was 1:94. The results suggest the potential use of vermiculite as decontaminating agent in well-designed fluidized bed columns.     

Cultivation of milk thistle (Silybum marianum L. Gaertn.), a medicinal weed

Milk thistle (Silybum marianum L. Gaertn.) is the most researched plant for the treatment of liver disease. Its therapeutic properties are due to the presence of silymarin, a mixture of three flavonolignans (silybin, silydianin and silycristin). The seeds contain the highest amount of silymarin, but the whole plant is used medicinally. Milk thistle is grown successfully on a range of soil types, from sandy soils to much heavier clay soils. Milk thistle is directly seeded in soils. Sowing occurs in autumn and spring, and row spacing is usually 40-75 cm, with 20-30 cm between plants in the row. Nutrient requirements of this crop are low to moderate since it is adapted to poor quality soils and many different growing conditions. A limiting factor in milk thistle production is weed interference. Pendimethalin and metribuzin herbicides are safe for weed control in milk thistle, both alone and in combination. Milk thistle is considered drought resistant and normal rainfall will often suffice. In a Mediterranean environment, under severe drought conditions, the crops should be irrigated during seed growth and filling. Moreover, a few varieties of milk thistle have been developed. The silymarin content most often ranges from 1.0% to 3.0% of achene dry matter but can exceed 8%. Efforts should be made to develop varieties with high silymarin content.     

Weed flora and seed yield in quinoa crop (Chenopodium quinoa Willd.) as affected by tillage systems and fertilization practices

The effects of tillage system and fertilization regimes on weed flora in quinoa (Chenopodium quinoa Willd.) were evaluated by means of two field experiments in 2011 and 2012. The experiments were laid out in a split-plot design with two main plots (conventional and minimum tillage) and four sub-plots (fertilization regimes). The results indicated that weed biomass and density in quinoa were influenced by the different fertilization and tillage treatments. Moreover, seed yield in conventional was 5%–13% higher than that of minimum tillage, probably due to the lower weed density and biomass. Concerning fertilization treatments, total weed density and biomass increased under manure application and inorganic fertilization. Tillage effects on weeds were species specific. The density of perennial weeds such as purple nutsedge (Cyperus rotundus L.) and the density of small-seeded weeds such as redroot pigweed (Amaranthus retroflexus L.) and common purslane (Portulaca oleracea L.) were significantly lower under the conventional tillage than under the minimum tillage system.     

Impact of variety and farming practices on growth,yield, weed flora and symbiotic nitrogen fixation in faba bean cultivated for fresh seed production

The main objective of this study was to investigate the performance of faba bean landraces originating from different regions of Greece under both organic and conventional farming systems focusing mainly on yield, biological nitrogen fixation (BNF), and competitiveness to weeds. Faba bean exhibited a high ability to fix nitrogen from the atmosphere, as indicated by the percentage of N₂ derived from the atmosphere which exceeded 75% in all evaluated varieties, and the total amount of biologically fixed N up to full anthesis, which fluctuated from 118.5 to 193.9?kg?ha^?1 in the various cropping systems and cultivars. The weed density was appreciably higher in the organic plots, without significant differences among the faba bean cultivars, while wild mustard and corn poppy were the most competitive weeds. The application of inorganic starter fertiliser in the conventionally-treated plots had no negative effect on biologically-fixed nitrogen by faba bean plants, while the herbicide pendimethalin had no negative impact on the nodulation process. Protein concentrations in faba bean cultivars fluctuated from 27.3% to 31.4%. The evaluated landraces could be utilised in breeding programmes due to their earliness, and their high performance in terms of protein content, BNF ability, and productivity.     

Effects of irrigation system and green manure on yield and nicotine content of Virginia (flue-cured) Organic tobacco (Nicotiana tabaccum), under Mediterranean conditions

Organic tobacco consists of a new industrial crop product. Field experiments were conducted to determine the effects of irrigation system and fertilization on the growth (biomass and roots) of organic tobacco plants (Nicotiana tabaccum cv NC 71). The experiment was designed as a split plot design with four replicates, two main plots (drip and sprinkler irrigation) and three sub-plots (vetch as green manure, red clover as green manure and control; without fertilization). Drip irrigation was characterised by lower amount of water applied to the soil. Furthermore the tobacco yield was not affected by the reduced water application and the crops under drip irrigation were higher than those with sprinkler irrigation. Positive effect of green manure in the nicotine content of tobacco leaves was also observed, and that reported for first time under organic system. Equally the higher amount of nitrogen from green fertilization with vetch led to increase of nicotine concentration (0.91% max concentration). Agronomic water use efficiency (WUE) for drip irrigation was always higher than those for sprinkler irrigation. There were no significant differences between the drip and sprinkler irrigation concerning the root biomass. Moreover, green manures increased roots dry weight. Yield of tobacco crop was significantly increased by the green manures, with the lowest yield (1850 kg ha^?1) to be found in the control plots. Finally, green manures increased the SPAD values and number of leaves, with most significant impact the time when vetch applied to soil.     

Pulsed electromagnetic fields effect in oregano rooting and vegetative propagation: A potential new organic method

Abstract

Many types of magnetic fields have already been investigated in order to find new methods to enhance plant growth. This study reports the positive effect of pulsed electromagnetic field on the main root characteristics (fresh weight, dry weight, root surface and length) of unrooted oregano stem cuttings. For oregano, vegetative propagation is commonly used, with rooted or unrooted stem cuttings, because seed propagation is not suggested for commercial cultivation. Oregano seeds are very small and, thus, difficult to handle. Vegetative reproduction in organic cultivation faces the ethical problem of the use of hormones to induce the rooting process in propagation beds. The purpose of this study was to determine if magnetic field can replace hormones in plant propagation and what the results of the combination of both magnetic field and hormones would be. Two types of stem cuttings were used (apical and middle) and the experiment was established in two different seasons (spring and autumn). The findings showed that magnetic field alone stimulates the rooting process in plant material, with results similar to or even statistically significantly better than those obtained using hormones. However, the combination of magnetic field and hormones resulted in measurements statistically significantly lower than with magnetic field alone. Such methods can potentially be useful for plant materials growers, providing better oregano seedlings, especially in organic farming, where chemical compounds are forbidden.     

Surface Soil Geochemistry for Environmental Assessment in Kavala Area, Northern Greece

The aim of the present study was to estimate the geochemical background and anomaly threshold values of the surface soils in Kavala, northern Greece. In order to reach this goal, a simple and practical procedure was applied. This procedure included the extraction of 42 major and trace elements by analytical grade HNO₃ from 65 surface soil samples, analysis by inductively coupled plasma?Coptical emission spectrometry and inductively coupled plasma?Cmass spectrometry, the distribution of the elemental data displayed on probability graphs (Q-Q plots), and the visualization of the results spatially by GIS software. The results indicated that natural factors mostly influence the elevated concentrations of Al, Ca, Fe, K, Mg, Si, B, Ba, Ce, Ga, Ge, La, Li, Mn Rb, Sb, Se, Sn, Sr, Y, and Zr, while anthropogenic activities mostly influence the elevated concentrations of Ag, As, Cd, Co, Cr, Cs, Cu, Hg, Mo, Ni, Pb, Th, Ti, U, V, W, and Zn. Nevertheless, almost all the elements determined showed their elevated concentrations inside the industrial part of Kavala area, which implies that the anthropogenic activities taking place in the study area, influence importantly the spatial distribution of the elements. The methodology followed in this research seems to be an adequate alternative for soil environmental studies.     

Evaluation of the field performance,nitrogen fixation efficiency and competitive ability of pea landraces grown under organic and conventional farming systems

In the present study, three pea Greek landraces Schinousa (AUASCHIN001), Andros (AUAANDRO001), and Amorgos (AUAAMORG001), and the commercial variety Onward were grown following either conventional or organic farming practices. The main objective of the study was to assess the suitability of these three landraces for organic cultivation as compared with a standard commercial variety. The total fresh pod yield produced by AUASCHIN001 and AUAAMORG001 was significantly lower than that obtained from ‘Onward’ and AUAANDRO001. Furthermore, the three landraces exhibited a higher competition to weeds than the commercial variety. Under organic farming conditions, AUASCHIN001 and AUAAMORG001 produced appreciably less shoot biomass than ‘Onward’ and this resulted in commensurate decreases in the total amount of BNF (biological nitrogen fixation) in their plant tissues, although the percentage of nitrogen (N) fixed from the atmosphere was significantly lower in ‘Onward’. AUAANDRO001 rendered the highest amounts of BNF in the organic farming systems, which was similar to that produced by ‘Onward’ in the conventional system. These results indicate that the tested landraces and especially AUAANDRO001 are more adaptable to low soil N levels and high weed competition, and thus they are more suitable for organic cultivation than ‘Onward’ which performs best in conventional cropping systems.