Marrubium friwaldskyanum Boiss (Lamiaceae) is a Bulgarian endemic species. Overall, the essential oil (EO) composition of M. friwaldskyanum was different from that of the other Marrubium species reported in the literature. The main EO constituents of M. friwaldskyanum were (E)-caryophyllene, germacrene D, and caryophyllene oxide. The effect of the harvest stage was significant only on α-copaene, (E)-caryophyllene, caryophyllene oxide, and τ-muurolol. The concentration of α-copaene (1.26–1.83% range of the total oil), (E)-caryophyllene (31–41%), caryophyllene oxide (6.4–11.8%), and τ-muurolol (1.3–2.8%) were the highest at 2–3 pair of leaves or before flowering and lower at flowering. The harvest stage did not significantly affect the concentrations of the other six identified EO compounds β-bourbonene (1.1%), α-humulene (2.8%), germacrene D (23.3%), bicyclogermacrene (2.85%), δ-cadinene (1.1%), and spathulenol (2.8%). In a separate experiment, grinding of the biomass prior to EO extraction had a significant effect only on the concentrations of D-limonene (0.24–3.3%) and bicyclogermacrene (3.6–9.1%). Grinding in water or without water, maceration, and addition of Tween®20 had rather small effects on the EO profile. The identified EO constituents and their mean concentrations in this experiment were (E)-caryophyllene (25.4%), germacrene D (17.6%), caryophyllene oxide (9.1%), spathulenol (6.5%), τ-muurolol (5.0%), carvacrol (3.9%), α-copaene (2.5%), β-bourbonene (2.5%), δ-cadinene (2.4%), α-humulene (1.8%), and Z-β-farnesene (1.3%). Embryological studies observed anther and the development of the male gametophyte and ovule and development of the female gametophyte of M. friwaldskyanum. Furthermore, pollen and seed viability assays were conducted, and mass spectrometry-based metabolomics analysis of an extract from shoots revealed the presence of 45 natural products, identified as flavonoids, phenolic acids, and (tri)terpenoids. Overall, the phytochemistry and some of the microscopic analyses distinguished this endemic species from other species in Marrubium.

The present research aims at evaluating the effect of silicon on the photosynthetic rate and the chlorophyll fluorescence parameters of hydroponically grown young cucumber plants (Cucumis sativus L.), cv. Gergana, under salinity stress. The experiment was conducted in a climatic chamber at the

In recent years, the light emitting diodes (LED) have become an alternative to the fluorescence lamp source of light for plant tissue culture, due to their low energy consumption, low heat emission, specific wavelength irradiation etc. The aim of this study was to investigate the effect of LEDs on the growth of in vitro cultivated raspberry (Rubus idaeus L. ‘Lloyd George’). The plantlets were cultivated in vitro under an illumination system based on Philips GreenPower LED research module. Four groups of LEDs emitting in white (W), red (R), blue (B), mixed (W:R:B:far-red=1:1:1:1) lights and fluorescent lamps (control) were used in our studies. Growth parameters, some physiological and biochemical characteristics of the plantlets were measured after three four weeks passages under corresponding light treatment. Our results indicated that different LEDs specifically influence the growth and development of in vitro cultivated raspberry plantlets and could be applied as an efficient lighting system for rapid in vitro micropropagation of Rubus idaeus L. The combination of blue, red, far red and white LEDs (1:1:1:1) stimulated the growth and biomass accumulation, as well as the intensity of net photosynthesis. For optimal results, it would be advisable to shorten the culture period to 3 weeks. This effective and affordable protocol would support the commercial micropropagation of raspberries and other soft fruits.

Rape is the main oilseed crop grown in many countries around the world. The seeds are used in the food industry for extraction of oil, as livestock feed or for production of biofuels. The high yield production requires the application of herbicides. The most commonly used herbicide in the cultivation of rape is Butisan S with active substance metazachlor. Often in adverse weather conditions the active substance enters the rape plants, causing a number of disturbances in the physiology-biochemical processes, but also represents a real risk of contamination of the yield. In the present study residues of metazachlor were identifi ed in samples of rape variety Xenon after soil application of the herbicide Butisan S at dose of 200 ml/da. The highest concentration (14,6 μg/g FW) was recorded in leaves 28 days after treatment with the herbicide. The concentration of metazachlor in rape plants decreased in time, with values of 4,4 μg/g FW at 48 days after treatment and 1,23 μg/g FW at 68 days. In foliar application of the herbicide the detected residues of metazachlor in leaves were lower with 4,24 μg/g FW on day 8 and 0,95 μg/g FW 20 days after treatment. The highest yield was recorded in the variant with soil application (200 ml/da) of the herbicide (yield 2683 kg/ha) as compared to the control (without herbicide application) (yield 1683 kg/ha).

The phytopathogenic fungus Taphrina deformans causing the so called "leaf curl disease" in peach trees leads to severe yield losses due to the development of leaf hypertrophy and subsequent necrosis and scission. Because of its economic importance, the molecular mechanisms underlying the onset and progression of the disease are of considerable interest to the agricultural science. In this study various biochemical parameters, including the activities of the antioxidant enzymes guaiacol peroxidase, syringaldazine peroxidase and catalase, total polyphenols and anthocyanin content, concentration of free proline, antiradical activity and quantity of plastid pigments, were characterized. All these were measured in both leaves with clear symptoms and distally situated leaves from the same plant that show no signs of the infection. The results demonstrate that the pathogen induces considerable biochemical changes concerning enzymatic and non-enzymatic elements of the plant defense and antioxidant systems. Moreover, it seems that the fungus provokes a systemic response detectable even in the tissues without observable symptoms.