Mikrosymptome des Bor-Mangels an Mentha piperita L.

Microsymptoms of boron deficiency in Mentha piperita L. The influence of boron deficiency on the development of oil glands and glandular hairs and on leaf and stem tissue development was studied. The experiments were carried out with Mentha piperita L. – var. Mitcham – under controlled experimental conditions in solution culture. Boron deficiency resulted in disturbances in the development of the vascular bundles and cambium extension. Excretions of dark substances could also be observed. Oil glands as well as glandular hairs were severely damaged under boron deficiency; the production of the essential oil decreased.     

Identification of monomenthyl succinate in natural mint extracts by LC-ESI-MS-MS and GC-MS

Fresh and dried mint leaves Mentha piperita (peppermint) and Mentha spicata (spearmint) were extracted in two different ways and the extracts investigated by high performance liquid chromatography-tandem mass spectrometry. All the ethanolic extracts prepared with Soxhlet apparatus were used in the identification of monomenthyl succinate as previously reported. The highest level was found in fresh spearmint leaves. The analysis of the extractions, prepared under mild conditions using a fluorinated solvent (HFC 134-a), confirmed the natural occurrence of monomenthyl succinate in the leaves, ruling out the hypothesis that this constituent could be an artifact of the Soxhlet extraction process. A method for identifying this compound in such a fluorinated solvent extract of mint leaf using preliminary esterification with diazomethane and then GC-MS is described.     

Determination of water-soluble polyphenolic compounds in commercial herbal teas from Lamiaceae: peppermint, melissa, and sage

Chromatographic techniques (HPLC and HPTLC) were used for qualitative and quantitative determination of eriocitrin, luteolin 7-O-rutinoside, luteolin 7-O-beta-glucuronide, lithospermic acid, rosmarinic acid, and methyl rosmarinate together with other known compounds in commercial herbal teas from the Lamiaceae family: peppermint leaf (Menthae piperitae folium), melissa leaf (Melissae folium), and sage leaf (Salviae officinalis folium). Contents of analyzed compounds in infusions, the most popular forms, were established using a C18 column with acetonitrile-water-formic acid as a mobile phase. The HPLC method was validated for linearity, precision, and accuracy. Luteolin 7-O-beta-glucuronide and lithospermic acid were identified as new Mentha x piperita compounds. The investigated herbal teas delivered polyphenols in high amounts, up to 182.2 mg for the infusion of one peppermint tea bag.     

Antimicrobial screening of Mentha piperita essential oils

Essential oils of peppermint Mentha piperita L. (Lamiaceae), which are used in flavors, fragrances, and pharmaceuticals, were investigated for their antimicrobial properties against 21 human and plant pathogenic microorganisms. The bioactivity of the oils menthol and menthone was compared using the combination of in vitro techniques such as microdilution, agar diffusion, and bioautography. It was shown that all of the peppermint oils screened strongly inhibited plant pathogenic microorganisms, whereas human pathogens were only moderately inhibited. Chemical compositions of the oils were analyzed by GC and GC/MS. Using the bioautography assay, menthol was found to be responsible for the antimicrobial activity of these oils.     

Monoterpene composition of essential oil from peppermint (Mentha x piperita L.) with regard to leaf position using solid-phase microextraction and gas chromatography/mass spectrometry analysis.

Monoterpene compounds of leaf pairs and flowers of Mentha x piperita have been studied by direct headspace sampling using solid-phase microextraction coupled with gas chromatography/mass spectrometry (SPME-GC/MS). The content of peppermint-characteristic compounds such as menthol, menthyl acetate, and neomenthol increased in a basipetal direction (older plant parts), whereas menthone and isomenthone showed higher levels in the acropetal direction (younger plant parts). Higher levels of menthofuran were found in peppermint flowers in contrast to the leaves. SPME sampling resulted in relatively higher amounts of high-volatile monoterpenes and lower detection of less volatile compounds such as menthol and menthone, compared to solvent-based samples from essential oil distillation.     

Flavor retention of peppermint (Mentha piperita L.) essential oil spray-dried in modified starches during encapsulation and storage

The effect of different commercial modified food starch carrier materials on the flavor retention of the essential oil (EO) of peppermint (Mentha piperita L.) during spray drying and storage was evaluated. The obtained results revealed that the emulsification and encapsulation efficiencies of peppermint EO were higher for all n-octenyl succinic anhydride (OSAN)-modified starches as compared to those of hydrolyzed starches (dextrins). The compositions of pure, emulsified, and encapsulated peppermint EOs in different matrices were quite similar; however, some changes in the percentages of some individual compounds were observed. Larger differences in the compositions of surface oils from various encapsulation products were obtained. Flavor components were released at different rates by each of the encapsulated products. The aroma binding capacity of different modified starch matrices to lock EO droplets depends on the water activity, and the leakage of aromas from encapsulated powder products during storage increased with increasing water activity.     

Biogenetic studies in Mentha x piperita. 2. Stereoselectivity in the bioconversion of pulegone into menthone and isomenthone.

Mentha x piperita shoot tips and first leaf pairs were fed with aqueous solutions of different deuterium-labeled pulegone and various enantiomeric distributions. The essential oil was extracted by solid-phase microextraction and analyzed using enantioselective multidimensional gas chromatography/mass spectrometry. The genuine p-menthan-3-ones (-)-menthone and (+)-isomenthone as well as their labeled analogues were analyzed simultaneously. Both enantiomers of labeled pulegone were converted into the corresponding labeled p-menthan-3-ones by Mentha x piperita, indicating an unspecific reduction process. The generation of 4S- and 4R-configured p-menthan-3-ones differed in their stereoselectivities. Labeled (S)-pulegone was reduced by Mentha x piperita more rapidly rather than (R)-pulegone. From a comparison of labeled pulegone enantiomers the bioconversion preferrably led to 4S-configured diastereomers.     

Dissipation of propiconazole and tebuconazole in peppermint crops (Mentha piperita (Labiatae)) and their residues in distilled oils

The broad-spectrum, systemic fungicides propiconazole (1) and tebuconazole (2) are used to control rust in peppermint (Mentha piperita L.). An analytical method, using gas chromatography combined with detection by high-resolution mass spectrometry, was developed to allow for the simultaneous monitoring of both pesticides in peppermint leaves and oil. Field trials were established to determine the rate of dissipation of tebuconazole and propiconazole in peppermint crops. Three applications of each fungicide were trialed at two rates (125 and 250 g of active ingredient (ai)/ha). At harvest, 64 days after the final application, propiconazole was detected at levels of 0.06 mg/kg and 0.09 mg/kg of dry weight, and tebuconazole was detected at 0.26 and 0.80 mg/kg dry weight, in identical trials. Rates of dissipation of propiconazole and tebuconazole were lower at a second trial site, where three applications of 125 g/ha ai for each fungicide resulted in residue levels of 0.21 mg/kg for both pesticides, detected 89 days after the last application. Propiconazole and tebuconazole were detected in the distilled oil at levels between 0.02 and 0.05 mg/kg and between 0.011 and 0.041 mg/kg, respectively. Propiconazole had a higher tendency to co-distill with the peppermint oil, with 0.7% of that present in the vegetative material ending up in the oil, compared to 0.09% of tebuconazole.     

Application of high-Cu compost to dill and peppermint

A controlled environment experiment was conducted to determine the effect of amending soil with various rates of high-Cu compost (0, 20, 40, and 60% compost/soil by volume) on dill (Anethum graveolens L.) and peppermint (Mentha X piperita L.) yields, on fractionation of Cu and Zn in soils, on elemental composition of soil and tissue, and on the essential oils. The compost contained about 2000 mg kg(-)(1) of Cu. Dill yields were greatest in the 20 or 40% treatments, but peppermint yields were greatest in the 20% treatment. Compost additions increased soil pH and electrical conductivity (EC), HNO(3) extractable soil B, Ca, K, Mg, Mn, P, S, Na, and Pb. Additions of high-Cu compost to soil increased tissue P, S, and Na in both crops and Mn, Mo, and Zn in dill but decreased tissue Ca, Cd, and Fe in both crops and Mn, Mo, and Zn in peppermint, increased Cu in all soil fractions including exchangeable, and increased tissue Cu of dill and peppermint as compared to unamended soil. Addition of 60% of high-Cu compost to soil resulted in 760-780 mg kg(-)(1) Cu in the growth medium. Nevertheless, Cu content in both crops reached only 12 mg kg(-)(1) DW in the 60% compost treatment, which is below the toxicity levels for plants and below the upper chronic dietary exposure for animals. The application of high-Cu compost altered chemical composition of dill and peppermint essential oils, but oils were free of Cu, Zn, Cd, Ni, Cr, and Pb. Results from this study suggest that mature composts with concentrations of Cu and Zn of 2008 and 321 mg/kg, respectively, can be used as a soil conditioner without risk for phytotoxicity or risk of increasing the normal range of Cu and Zn in crop tissue. However, the long-term effect of the accumulation of heavy metals in soils following repeated compost applications needs to be carefully considered.     

Biosynthesis of menthofuran in Mentha x piperita: stereoselective and mechanistic studies.

Mentha x piperita shoot tips and first leaf pair were fed with aqueous solutions of [(2)H(2)]- and [(2)H(2)]/[(18)O]-labeled pulegone. The essential oil was analyzed by solid phase microextraction and enantioselective multidimensional gas chromatography/mass spectrometry. After feeding experiments with labeled pulegone racemate, both labeled (S)-menthofuran and (R)-menthofuran were detectable simultaneously together with genuine (R)-menthofuran. It could be shown that both labeled pulegone enantiomers are converted by Mentha x piperita to the corresponding labeled menthofuran enantiomers, favoring the labeled analogue of the nongenuine (S)-pulegone. The oxygen in menthofuran is introduced by enzymatic oxidation of pulegone, as concluded from feeding experiments with mixed labeled [(2)H(2)]/[(18)O]pulegone.     

缺硼对绿豆叶片光合特性和碳水化合物含量的影响

本试验以绿豆为指示植物,采用溶液培养法研究了缺硼对叶片光合功能和碳水化合物含量的影响,以明确缺硼是否影响光合作用进而影响作物生长。在绿豆第二片真叶出现后的第二天,一半植株供给 50 mol/L 硼（高硼）,另一半植株供给0.2 mol/L 硼（低硼）,在叶片生长过程中动态监测叶绿素含量、 气体交换和碳水化合物含量。结果表明,缺硼对叶片叶绿素含量没有影响,缺硼降低了光合速率（Pn）和气孔导度（Gs）,但对胞间二氧化碳浓度（Ci）没有影响; 缺硼提高了气孔限制率（Ls）。虽缺硼降低了Pn,但提高了叶片中可溶性糖,特别是葡萄糖和淀粉的含量。本研究结果表明缺硼对植物生长的影响并非是由于碳水化合物缺乏的缘故,而是因降低库活力导致了Pn的降低。     

Effect of harvest time and drying method on biomass production, essential oil yield, and quality of peppermint (Mentha x piperita L.)

In the period from 2000 to 2002, studies on peppermint (Mentha x piperita) herb and essential oil (EO) production have been conducted at Planteforsk, Apelsvoll Research Centre Div. Kise in Norway. The trials were aimed at finding the optimal harvest date and suitable drying methods to maximize EO yield and to obtain a desirable oil quality. Peppermint plants from the first production year (2000 and 2001) and the second production year (2002) were harvested during flowering at three developmental stages (early, full, and late bloom). Biomass and leaf production were recorded, and the water content of the plant material was detected after the application of different drying methods: instantaneous drying at 30, 50, and 70 degrees C and prewilting (ground drying) for 1 or 5 days followed by final drying at 30 degrees C. Finally, plant samples were transferred to The Plant Biocentre at NTNU, Trondheim, Norway, for hydrodistillation and gas chromatography-mass spectrometry (GC-MS) analyses of the EOs. Peppermint oil yield increased from early to full bloom and late bloom (average of all years and drying methods except for 50 and 70 degrees C: 2.95, 4.13 and 4.20 L/daa, respectively) as an effect of biomass production and leaf growth. The flavor-impact compounds, menthol and menthone, reached their optimum at full bloom (43-54 and 12-30%, respectively). Prewilting led to slight decreased EO levels after 1 day (7.7%) and 5 days of ground drying (1.5%) and no EO quality changes, compared to direct drying at 30 degrees C. The plant weight (H2O content) was drastically decreased to the average under 80 and 45% in all years, thus reducing the energy supply and costs for the necessary final drying step.     

Der Einfluß von Dicyandiamid und N-Serve in Verbindung mit Ammoniumsulfat als N-Dünger auf die Nitrat- und Oxalsäuregehalte von Spinat (Spinacia oleracea)

Occurence of boron deficiency in Citrus aurantium L. (Bitter orange) at the Caspian Sea (Iran) In a Bitter orange plantation near the Caspian sea over a period of two years different amounts of boron were applied either as borax to the soil or as Solubor to the leaves. Without boron supply the fruits were misshapen, had a rough and thick peel and often brown spots in the pulp. Supply of 5 – 20 g B per tree prevented the occurence of these symptoms and increased both the fruit size and the proportion of the pulp. Without boron supply on fresh weight basis the proportion of pulp/peel was 1 : 1, 6 – 2, 0 as compared to 1 : 0, 6 – 0, 7 with boron supply. The effect of the different boron supply was well reflected in the boron content of the leaves and especially of the fruits. Borax increased the boron content of the plants more than Solubor. Conzidering both the low content of available boron in most of the soils of the Citrus area near the Caspian sea and the special ecological conditions (high pH values and low water content of the soils during fruit development) boron deficiency can be expected. The results of the experiment with Bitter oranges confirm that boron fertilizing is an important factor for plant production in this area.     

黄瓜缺硼症状与激素变化关系的研究

在营养液培养条件下 ,研究了黄瓜缺硼处理不同时间外部症状及其体内乙烯和IAA含量变化。结果表明 ,缺硼处理后 5d ,黄瓜幼叶开始出现缺硼症状 ;叶片中IAA含量降低发生在缺硼处理后处理后 3d ,即缺硼症状出现之前 ;乙烯释放量增加则发生在处理后 5d ,是伴随缺硼症状出现而升高的 ;生长点中IAA累积则发生在缺硼处理后处理后 6d ,即缺硼症状出现之后。黄瓜根尖在缺硼处理 3d ,缺硼症状就十分明显。缺硼黄瓜体内IAA平衡遭到破坏可能是缺硼症状出现的主要原因     

Changes in the enantiomeric distribution of selected volatile constituents of Mentha pulegium L. powders caused by hot water treatment

The variation, in general, of the composition of the aromatic fraction and, in particular, of the enantiomeric composition of certain chiral volatile compounds of commercial Mentha pulegium L. powders caused by boiling water was evaluated. A comparison between the volatile profile of the studied herbs demonstrated that most M. pulegium L. samples contained high proportions of Mentha piperita L., even when this information was not specified on the label. Likewise, substantial changes in the volatile fraction of the infusions with respect to the composition of the original plant used in their preparation were found. The enantiomeric composition of some chiral compounds of the dried plant material, particularly limonene, was modified by adding hot water, whereas others were kept invariable. The results shown in this work reflect the need for the control of the composition of commercial powders and brews of M. pulegium L. to ensure their correct application.     

钙镁缺乏对不同甘薯品种的生长及矿质元素吸收的影响

为了探索钙、镁元素缺乏对不同甘薯品种的生长及矿质元素吸收的影响,采用砂培的方法,以苏16和苏11为材料,在钙、镁缺乏条件下,对其外观症状、叶绿素含量、光合作用、地上与地下部分生物量及其根部和叶部矿质元素含量进行了研究。结果表明:钙、镁缺乏时苏16和苏11的叶绿素含量、净光合速率、地上和地下生物量均显著下降,苏11的下降幅度比苏16大,缺钙条件下,苏16的显著症状为烂根,并且只有根部和叶部的钙含量显著下降(P0.05),苏11的典型症状为老叶坏死的斑块沿着靠近叶柄的叶边缘不规则向外扩散,逐渐衰老枯落,并且根部钙含量显著降低伴随铁的显著降低(P0.05),可能伴有缺铁并发症,缺镁条件下,苏16和苏11的典型症状相同,叶片均失绿,老叶逐渐枯萎脱落,并且根部和叶部的镁含量显著降低伴随着硫含量的显著降低(P0.05),可能伴有缺硫并发症。     

Effects of magnesium remobilization and allocation on banana plant growth

Magnesium (Mg) is known as one of the mobile elements and can move from the lower to upper leaf blade when the plants suffer from Mg deficiency. It is generally recognized that symptoms of Mg deficiency appear on lower leaves. This study was conducted to reveal the effect of Mg deficiency stress on remobilization of Mg and nitrogen in banana plant and to collect the typical symptoms of Mg deficiency. Quartz sand cultures were used to study the effect of Mg deficiency on banana growth and its mobilization and allocation in the plants. Results showed that chlorosis, a typical symptom of Mg deficiency, occurs in the second leaf from top of banana plant after 35 days of Mg deficiency. Necrosis of the whole leaf in the middle part of banana and a significant reduction of leaf area from the top to middle leaves are detected. However, older leaves remain green, and their area is not affected. Mg is more stable in the banana plant and cannot be remobilized and transported from the old to young leaves under Mg deficiency. After 195 days of Mg deficiency, the growth and Mg nutrition of Mg-deficient plant can be normalized by the restoration of Mg nutrient after 49 days of deficiency. Therefore, Mg in banana leaves is not mobile and reusable from older to younger leaves.     

Correlation of leaf chlorophyll readings and stem nitrate concentrations in peppermint

Abstract

The SPAD chlorophyll meter appears promising for rapid, on‐farm analysis of crop nitrogen (N) status. Leaf SPAD chlorophyll levels have been correlated with total leaf N concentrations, but it has not been determined how they relate to other widely applied N diagnoses such as petiole or stem nitrate (NO₃) analysis. Our objective was to examine the relationship between leaf SPAD readings and stem NO₃ levels in peppermint (Mentha piperita L.). Upper canopy SPAD chlorophyll and stem NO₃ concentrations were determined weekly during two seasons for peppermint grown with variable N inputs. Leaf SPAD levels exhibited significant linear‐plateau responses with respect to stem NO₃, indicating that SPAD readings do not respond to luxury N consumption. The meter is therefore promising for the detection of crop N deficiencies by comparison of production fields to well fertilized plots or strips. Break‐points in the linear‐plateau regressions describe saturation concentrations of stem NO₃ with respect to leaf SPAD levels peaking at 12,000 mg NO₃‐N/kg in mid to late July and declining later in the season. The SPAD meter may be applied directly to N management by use of reference plots or it may be used as a tool to aid in determination of criteria for other diagnoses such as tissue NO₃.     

Gewebekulturen unter Bormangel

Tissue culture under conditions of boron deficiency Cambium tissue from sunflowers and carrots were cultured in nutrient solution according to Murashige and Skoog with graduated supplies of boron. A light-coloured and well growing callus was formed only in the presence of boron. Explants on a boron-deficient medium agglutinated at the edges, had only small areas of cell division and revealed appositions on the walls of some cells. Deficient tissues also became noticeably darker. Callus grown on normal medium and then transferred to boron-deficient medium slowed down in growth rate – at the latest after 4 weeks – and also turned dark. In contrast to normal calli, the deficient cultures could not be easily separated in water into individual cells or small cell groups. Moreover, the cells were smaller on the average and often revealed grainy contents and (in the case of carrots) accumulation of plasma at the ends of the cells. A large number of deficient cells were plasmolyzed. An accumulation of undifferentiated cells in the cambium region is particularly striking in dicotyledons under conditions of boron deficiency. If this symptom should be the result of cell division activity, then isolated cambium should react to boron deficiency with intensive cell division. Contrary to expectation, isolated cambium of sunflowers and carrots in tissue culture did not reveal a promotion of cell division under conditions of boron deficiency. These results indicate that the symptom of “increased cambium growth” in intact dicotyledons is due to a secondary effect of boron deficiency.     

Boron stress inhibits beet (Beta vulgaris L.) growth through influencing endogenous hormones and oxidative stress response

Objective: This study aimed to evaluate the pleiotropic effects of boron stress on beet (Beta vulgaris L.) growth.

Methods: Beet seedlings were treated with varying concentrations of H₃BO₃ (0.05, 0.5, 2, and 30 mg/L) for 30 d for evaluation of diverse morphological parameters related to shoot and root growth. Transverse sections of beet leaves were observed under a microscope, and the leaf thickness was measured. Photosynthesis in beet was evaluated by measuring the photosynthetic rate, intercellular carbon dioxide concentration, and chlorophyll content; chloroplast morphology was observed by transmission electron microscopy. In addition, the levels of diverse endogenous hormones, as well as oxidative stress parameters, were also analyzed in beet leaves.

Results: We found that boron accumulated in different beet tissues but was observed mainly in mature leaves, followed by young leaves, mature petioles, young petioles, and roots. Boron stress (boron toxicity, 30 mg/L; boron deficiency, 0.05 mg/L) significantly inhibited beet shoot, root growth, and leaf expansion while promoting leaf thickening. Additionally, the levels of indole-3-acetic acid, gibberellin A3, and zeatin in beet leaves decreased significantly under boron stress, whereas the level of abscisic acid increased. Moreover, the levels of superoxide dismutase, peroxidase, catalase, malondialdehyde, and proline in beet leaves increased significantly under boron stress.

Conclusion: Together, our results indicate that boron stress significantly inhibited normal beet growth via the influence of endogenous hormone levels and oxidative stress responses.