Stem slices (1-mm thick) cut from apple microshoots were cultured on a modified Murashige-Skoog medium with indole-3-acetic acid (IAA) or a-naphthaleneacetic acid (NAA), and increasing concentrations of various phenolic compounds. Both auxins were added at a concentration suboptimal for rooting. Indole-3-acetic acid is metabolized through oxidation and conjugation but NAA through conjugation only; which might have affected the results. With IAA, all tested orthodiphenols, paradiphenols and triphenols promoted adventitious root formation from the stem slices. Ferulic acid (FA, a methylated orthodiphenol) had the largest effect and increased the number of adventitious roots from 0.9 to 5.8. With NAA there was little or no promotion after addition of phenolics. Phloroglucinol (a triphenol) and FA were examined in detail. Their effects on the dose-response curve of IAA and the timing of their action indicated that both acted as antioxidants protecting IAA from decarboxylation and the tissue from oxidative stress. Experiments with carboxyl-labelled IAA showed that IAA was massively decarboxylated by the slices and that decarboxylation was strongly reduced by phenolics. Decarboxylation was to a great extent attributable to the wound response and did not occur to such an extent in non-wounded plant tissues. In shoots, FA promoted little rooting. Slices were cultured on top of the medium and shoots were stuck into the medium. Possibly, the anaerobic conditions in the medium near the basal part of the stem of shoots reduced the wound response and consequently decarboxylation of IAA. The monophenolic compound salicylic acid (SA) promoted IAA decarboxylation. Accordingly, SA reduced rooting when added during the initial days of the rooting process (the period during which auxin enhances rooting), and promoted outgrowth of root primordia later on (the period during which auxin inhibits rooting).

No abstract

No abstract

The water-energy nexus reveals that large amounts of energy is stored in used water and can be used as an energy source. Anaerobic fermentation is an excellent ecological waste treatment and a way of producing low cost electrical and thermal energy. By using digestate resulting from biogas production instead of synthetic fertilizers derived from natural gas, we can save energy, cut consumption of fossil fuels and reduce our carbon footprint. The aim of this study then is to determine the effect of digestate on the yield and quality of crop production as well as its effect on the immediate environment. A ratio of raw materials in biogas, pig manure and vegetable wastes of 70:30 was used on lettuce as an indicator culture. The studies were carried out on two different soil types. Digestate was applied at various percentages, tested with untreated soil as control. The results are encouraging indicating that digestate as a biomass is rich in macro and micronutrients and can be used in agriculture for the improvement of soil fertility.

The aim of this study is to establish changes that may occur after a prolonged application of wastewater sludge treated to biosolids, in the 'soil-fertilizer-plant' system. Thirteen experimental plots with different soil types planted with experimental crops were investigated in order to evaluate the suitability of these biosolids as soil conditioners and fertilizers. The biosolids were incorporated in soil starting in 2006 in different quantities (from 6 tons per ha) for various arrays. The rate of application was calculated on the basis of imported nitrogen and was consistent with the characteristics of the sludge, soil diversity, growing crop requirements, and other factors. In 2013 (after 7 years of land use) average soil samples from the same arrays were taken and analyzed. No chemical fertilizer was applied during the experimental period. The results show that the use of sewage biosolids as a soil improver in accordance with local legislation does not pose any serious environmental risks but can maintain and improve soil fertility and crop yield. A slight increase in Cu and Zn in plants was detected, however the content of heavy metals in all soil samples was below maximum allowable limits and no signs of phytotoxicity were observed.