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The use of color shading nets for cultivation of some ornamentals and vegetables has become common. Thus, observing the great influence of the solar radiation on the plant physiology, the objective of this research was to evaluate the the quantity and quality effects of spectral light transmitted through color shading nets (Chromatinet®) in Melissa officinalis L., including physiological aspects as:growth ,content and chemistry composition. Four treatments and five replications were disposed in a completely randomized design, being each experimental unit composed by four pots (one plant per pot). The treatments were lemon balm's plants cultivated under full sunshine, black shading net (50%), red shading net (50%) and blue shading net (50%). The characteristics evaluated were: plant's height; dry phytomass of leaves, stems, aerial part, roots and total; root/aerial part ratio; total leaf area; leaf area ratio; leaf weight ratio; specific leaf area; content, yield and composition of the essential oil. The utilization of nets favored the growth organs dry phytomass yield, independently of the color, in comparison with total sun light. Plants under red shading had lower content of essential oil and yield, but they showed the higher content of citral. [ABSTRACT FROM AUTHOR]

The present work was carried out with the objective of evaluating the effect of the culture medium in the content and chemical composition of the essential oil of Melissa officinalis, evaluating three concentrations of the MS culture medium. The experiment was performed in a completely randomized design, with 7 repetitions, where each repetition was represented by 20 g of fresh biomass. Oil extraction was accomplished using a Clevenger modified device for 1 hour and 30 minutes, and the chemical analysis was accomplished by gas chromatography. It was observed that the content and chemical composition of the essential oil of M. officinalis was influenced by the concentration of MS medium. The plants grown in the MS medium and MS/4 presented higher content of essential oil, and the major components of these plants were geraniol (25.23 and 16.21%, respectively) and nerol (24.5 and 20.53%, respectively). The major component present in the oil of melissa plants cultivated in MS/2 was neryl acetate (18.69%). [ABSTRACT FROM AUTHOR]

Drip irrigation is one of the agricultural techniques mostly used to grow a wide variety of vegetable crops. Studies focused on improving this technique based on using magnetized water, as well as on investigating its effects on medicinal plant production processes, remain incipient in the literature. Some benefits of this technique are the optimization of the quality and quantity of irrigation water, economy of the water absorbed by the plants, improvement in the vegetative growth and productivity, reduction of the use of fertilizers and the greater availability of nutrients in the soil for crops compared to irrigation using conventional water. Thus, the aim of the current study is to assess the effect of different magnetized and non-magnetized water irrigation levels on Melissa officinalis growth, nutritional status and essential oil compounds in plants grown in protected environment. The experimental design consisted of completely randomized design with two water types (magnetized and non-magnetized) and four irrigation levels (25%, 75%, 100% and 125% of crop evapotranspiration - ETc) with four replications. Irrigation conducted with different magnetized water levels had significant effect on the accumulation of nitrogen, phosphorus, sulfur, and of all micronutrients in plants' leaves, and on soluble protein contents. The study also demonstrated significant effects of magnetically treated irrigation water on major chemical compounds such as citral (neral + geranial) and citronellal on the leaves of lemon balm plants. Different water levels significantly affected plant dry weight production parameters. In this study it was shown that the plant treated with magnetized water required less amount of water applied being a promising potential in saving water resources that will be of significant importance in the future. Overall, the results need to be further tested under field conditions to assess the usefulness of magnetic irrigation water treatment.in cultivation with medicinal, aromatic and spice plants. It is hoped that this study can contribute to improving water management, reducing the environmental impact without implying great costs for the producer. [Display omitted] • Increasing irrigation levels based on crop evapotranspiration increases dry weight. • Magnetized water at levels higher than 25% ETc increases mineral nutrients' content. • Magnetized water at levels higher than 25% ETc increases protein contents in leaves. • Magnetized water favors the synthesis citral (neral + geranial). • Magnetized water favors the synthesis citronellal constituent in essential oil. [ABSTRACT FROM AUTHOR]

• Arbuscular mycorrhizal fungi (AMFs) provided significant dry weight gain for plants. • Cattle manure source influenced the growth of Melissa officinalis. • AMFs and organic manure influenced essential oil content. • AMFs and in the presence of cattle manure contributed to the accumulation of citral. • AMFs led to the accumulation of total phenols. The use of arbuscular mycorrhizal fungi (AMFs) during cultivation is a promising possibility to increase biomass and essential oil yield of medicinal plants. The objective of the present study is to observe the influence of AMFs and fertilization with organic manure (OM) on Melissa officinalis growth, phenols, flavonoids, and on the chemical composition of its essential oil. The treatments were: (+)AMF(-)OM (with fungi and without organic manure), (+)AMF(+)OM (with fungi and with organic manure), (-)AMF(+)OM (without fungi and with organic manure), and (-)AMF(-)OM (without fungi and without organic manure)-control. Leaf (LDW), stem (SDW), root (RDW), shoot (ShDW), and total dry weight (TDW), shoot/root ratio (S/R) and total leaf area (TLA) were calculated 90 days after spore density counting and root colonization. Infection rates recorded for treatments inoculated with AMFs ranged from 47.95 to 53.55 %. The treatment inoculated with this fungus, without organic fertilizer, presented longer plant length (19.0 cm) than the control (16.6 cm). Inoculation with AMFs was significant for dry weight gain in comparison to the control. Organic fertilization also affected plant's dry weight gain. The highest essential oil content means were observed in treatments with AMFs and manure (0.27 %); this outcome was statistically different from that without AMFs and manure (0.16 %). Based on the PCA analysis, inoculation with AMFs - without/with organic fertilizer - had positive influence on the content of citral (geranial + neral), phenols, and flavonoids in the current study. Accordingly, the use of AMFs and cattle manure has influenced dry weight production, content, and yield, as well as the chemical constituents of the essential oil. According to these findings, the combination of these practices can enhance production in the cultivation of this species, and allow greater dry weight, yield, and active ingredient content. [ABSTRACT FROM AUTHOR]