Inhibition of germination and α-amylase induction by 6-methoxy-2-benzoxazolinone in twelve plant species

6-Methoxy-2-benzoxazolinone (MBOA) inhibited germination of rice (Oryza sativa L.), wheat (Triticum aethiopicum Jakubz), rye (Secale cereale L.), onion (Allium cepa L.), wild oat (Avena fatua L.), barnyard grass [Echinochloa crus-galli (L.) Beauv.], ryegrass (Lolium rigidum Gaudin), cress (Lepidium sativum L.), lettuce (Lactuca sativa L.), tomato (Lycopersicum esculentum Mill.), carrot (Daucus carota L.) and amaranth (Amaranthus retroflexus L) and the inhibition increased with increasing MBOA concentrations. MBOA also inhibited the induction of α-amylase in these plant seeds and the inhibition increased with increasing MBOA concentrations. There were variations in sensitivity of these plant species to MBOA, and species of family Poaceae (barnyard grass, wild oat, rice, rye, ryegrass, and wheat) were less sensitive to MBOA than the other plant species.     

Isolation and identification of a plant growth inhibitor from Tinospora tuberculata Beumee

Tinospora tuberculata Beumee has been used widely as a folk medicine and several bioactive compounds have been isolated. However, no herbicidal compound has been reported in this species. Therefore, we investigated the presence of phytotoxins in T. tuberculata. The aqueous methanol extracts of T. tuberculata inhibited the growth of roots and shoots of cress (Lepidum sativum L.), lettuce (Lactuca sativa L.), timothy (Phleum pratense L.) and barnyard grass (Echinochloa crus-galli (L.) Beauv.). The extract was then purified by several chromatographic runs with monitoring the inhibitory activity and the main phytotoxic substance was isolated. The chemical structure of the compound was determined by spectral data as syringin (4-[(1E)-3-Hydroxyprop-1-en-1-yl]-2,6-dimethoxyphenyl β-d-glucopyranoside). It inhibited the root and shoot growth of all test plant species at concentrations >10 µM. The concentrations required for 50 % inhibition of root and shoot growth of cress and lettuce ranged from 78.2 to 412 μM, and that of timothy and barnyard grass renged from 9.8 to 73.2 µM. Effectiveness of syringin on monocotyledonous (timothy and barnyard grass) plants was greater than that on dicotyledonous (cress and lettuce) plants. These results suggest that syringin may contribute to the allelopathic effect caused by the T. tuberculata extract.     

The purification and characterization of a novel lipid transfer protein from caryopsis of barnyard grass (<Emphasis Type="Italic">Echinochloa crusgalli</Emphasis>)

A novel lipid transfer protein called Ec-LTP was isolated from resting caryopsis of weed barnyard grass Echinochloa crusgalli (L.) Beauv.; its molecular weight, amino acid content and N-terminal amino acid sequence were determined. Ec-LTP was a 9150 D protein, containing eight cysteine residues, which formed four disulfide bonds. The isolated protein could significantly inhibit the development of pathogenic fungi Phytophthora infestans and Helminthosporium sativum, causing the late blight of potato and tomato and the root rot of herbs, respectively.     

Interplanting Annual Ryegrass,Wheat, Oat,and Corn to Mitigate Iron Deficiency in Dry Beans

This study evaluated whether grass intercropping can be used to alleviate Fe deficiency chlorosis in dry beans (Phaseolus vulgaris L.) grown in high pH, calcareous soils with low organic matter. Field studies were conducted at the University of Wyoming Sustainable Agriculture Research and Extension Center in 2009 and 2010. Black- and navy beans were grown alone or intercropped with annual ryegrass (Lolium multiflorum Lam.), oat (Avena sativa L.), corn (Zea mays L.), or spring wheat (Triticum aestivum L.) in a two-factor factorial strip-plot randomized complete block design. All four grass species increased chlorophyll intensity in dry beans. However, grass species did not increase iron (Fe) concentration in dry bean tissues suggesting inefficient utilization of Fe present in the dry bean tissues. In 2009, nitrate-nitrogen (NO₃-N) and manganese (Mn) concentration in bean tissue were greater in bean monoculture than in grass intercropped beans. Bean monoculture also had greater soil NO₃-N concentrations than grass intercropped treatments. In 2009, grass intercrops reduced dry bean yield >25% compared to bean monoculture. Annual ryegrass was the least competitive of the four annual grass species. This suggests that competition from grasses for nutrients, water, or light may have outweighed benefits accruing from grass intercropping. Additional studies are required to determine the appropriate grass and dry bean densities, as well as the optimum time of grass removal.     

Allelopathic Substance Exuded from a Serious Weed, Germinating Barnyard Grass (Echinochloa crus-galli L.), Roots

The allelopathy of a serious weed, barnyard grass (Echinochloa crus-galli L.), was investigated. Root exudates of young barnyard grass showed allelopathic effects and plant-selective activity and inhibited root elongation of all plants tested. With respect to shoot growth, the exudates did not show inhibition of barnyard grass only. The allelopathic substance was isolated and identified as p-hydroxymandelic acid by NMR. p-Hydroxymandelic acid strongly inhibited shoot growth and root elongation of all plants tested. The effects of three congeners of p-hydroxymandelic acid were tested on rice shoot growth. In the biological activity exhibited in rice, shoot growth was related to the hydroxyl groups. Received October 7, 1998; accepted March 29, 1999     

Organ-specific-active allelopathic substance in red pine needles

An organ-specific-growth inhibitory substance was isolated from an aqueous methanol extract of red pine needles and determined by spectral data as 1-mono(16-hydroxyhexadecanoyl)glycerol. This substance inhibited root growth of cress (Lepidium sativum L.) and barnyard grass (Echinochloa crus-galli (L.) Beauv) seedlings at concentrations greater than 0.01 and 0.03???M, respectively. The concentrations required for 50?% growth inhibition on roots of cress and barnyard grass were 0.16 and 3.4???M, respectively. However, the inhibitory activity of the substance on shoots of cress and barnyard grass was very weak. The endogenous concentration of 1-mono(16-hydroxyhexadecanoyl)glycerol in the pine needles was 4.6???mol?kg^?1. Two related compounds, 1-monohexadecanoylglycerol and 16-hydroxyhexadecanlic acid had no activity up to 1,000???M on cress roots and shoots. The effectiveness of 1-mono(16-hydroxyhexadecanoyl)glycerol on root growth inhibition and the occurrence of 1-mono(16-hydroxyhexadecanoyl)glycerol in pine needles suggest the substance may play an important role in the allelopathy of red pine. Root-specific-growth-inhibition by the substance may be one of the strategies for red pine to compete with neighboring plants for nutrients and space because root growth of competitive plants may be very important for their whole plant development.     

Changes in Dry Matter, Carbohydrate and Seed Yield Resulting from Lodging in Three Temperate Grass Species

The adverse effect of lodging on grass seed yield may be attributed,in part, to assimilate limitation during the seed filling period.This investigation examined plant dry matter assimilate partitioningand seed yield as affected by lodging in three species thatare closely related but phenotypically different: tall fescue(Festuca arundinacea Schreber.), Italian ryegrass (Lolium multiflorumLam.), and perennial ryegrass (L. perenne L.). Studies wereperformed in field plots at Corvallis, Oregon, USA. Seed yieldcomponents (seed number per inflorescence, seed yield per inflorescence,and single seed mass) and leaf, stem (lower, middle, and peduncle)and seed inflorescence dry mass were measured just prior toanthesis to seed maturity. Dry mass and water soluble carbohydrates(WSC) were determined for shoot components. The reduction indry mass and WSC in leaves and stem components following anthesiswas often greater in lodged plants compared to upright plants.The relatively low seed yield depression in lodged tall fescuesuggested a higher compensation potential for partitioning reserveassimilate from leaves and stems to support seed growth anddevelopment. This potential does not appear to be present tothe same degree in Italian ryegrass and to an even lesser extentin perennial ryegrass. These findings suggest that the potentialto compensate for reduced assimilate supply during the periodof high assimilate demand by seeds may be attributed, in part,to the total assimilate reserve accumulated prior to photoassimilatereduction caused by the lodged condition. Copyright 2000 Annalsof Botany Company Tall fescue, Festuca arundinacea Schreber., Italian ryegrass, Lolium multiflorum Lam., perennial ryegrass, L. perenne L., assimilate partitioning, source–sink     

Barnyard grass-induced rice allelopathy and momilactone B

Here, we investigated chemical-mediated interaction between crop and weeds. Allelopathic activity of rice seedlings exhibited 5.3-6.3-fold increases when rice and barnyard grass seedlings were grown together, where there may be the competitive interference between rice and barnyard grass for nutrients. Barnyard grass is one of the most noxious weeds in rice cultivation. The momilactone B concentration in rice seedlings incubated with barnyard grass seedlings was 6.9-fold greater than that in rice seedlings incubated independently. Low nutrient growth conditions also increased allelopathic activity and momilactone B concentrations in rice seedlings. However, the increases in the low nutrient-induced allelopathic activity and momilactone B concentration were much lower than those in barnyard grass-induced allelopathic activity and momilactone B concentration. Root exudates of barnyard grass seedlings increased allelopathic activity and momilactone B concentration in rice seedlings at concentrations greater than 30 mg/L of the root exudates, and increasing the exudate concentration increased the activity and momilactone B concentration. Therefore, barnyard grass-induced allelopathic activity of rice seedlings may be caused not only by nutrient competition between two species, but also by components in barnyard grass root exudates. As momilactone B shows strong allelopathic activities, barnyard grass-induced allelopathic activity of rice may be due to the increased concentration of momilactone B in rice seedlings. The present research suggests that rice may respond to the presence of neighboring barnyard grass by sensing the components in barnyard grass root exudates and increasing allelopathic activity by production of elevated concentration of momilactone B. Thus, rice allelopathy may be one of the inducible defense mechanisms by chemical-mediated plant interaction between rice and barnyard grass, and the induced-allelopathy may provide a competitive advantage for rice through suppression of the growth of barnyard grass.     

Mechanism for the differential translocation of amiben in plants

The proportion of the total plant radioactivity present in shoots at the end of a 24-hour exposure of the roots to 0.5 milligram per liter ¹⁴C-3-amino-2,5-dichlorobenzoic acid (¹⁴C-amiben) ranged from 1.4 to 74.3% in 13 species. When roots of 10-day-old wheat (Triticum aestivum L. em. Thell., Triumph) and 13-day-old barnyard grass (Echinochloa crusgalli L. Beauv.) plants were treated with 0.5 milligram per liter ¹⁴C-amiben for 12 or 24 hours, barnyard grass shoots contained at least eight times more of the total plant radioactivity than did wheat shoots. In similar experiments with ¹⁴C-2-chloro-4-(ethylamino)-6-(isopropylamine)-s-triazine (¹⁴C-atrazine), there were no differences in translocation between these two species.     

The chemical-mediated allelopathic interaction between rice and barnyard grass

Aims

The possible involvement of the chemical-mediated interaction in allelopathy between rice and barnyard grass was investigated.

Methods

Effcts of rice seedlings and rice root exudate on the alleloapthic activity of barnyard grass were determined and a key compound invovled in the allelopathic interaction between rice and barnyard grass was isolated.

Results

Allelopathic activity of barnyard grass was increased by the presence of rice seedlings. Rice root exudates also elevated the allelopahtic activity of barnyard grass. A key compound, which increased the allelopathic activity of barnyard grass, in the rice root exudates was isolated and determined as momilactone B. Momilactone B increased the allelopathic activity of barnyard grass at concentrations greater than 3 μM, and increasing the momilactone B concentration increased the activity.

Conclusions

Momilactone B is known to act as a potent rice allelochemical and to possess strong growth inhibitory activity against barnyard grass. The present research suggests that barnyard grass may response to the presence of neighboring rice by sensing momilactone B in rice root exudates and increase allelopathic activity. Thus, momilactone B may not only act as a rice allelochemical but also play an important role in rice-induced allelopathy of barnyard grass. The induced-allelopathy may provide a competitive advantage for barnyard grass through the growth inhibition of competing plant species including rice. Barnyard grass allelopathy may be one of the inducible defense mechanisms by chemical-mediated plant interaction between rice and barnyard grass. Rice allelopathy was also reported to be increased by the presence of barnyard grass through increasing production and secretion of momilactone B into surrounding environments. During the evolutional process, rice and barnyard grass may have developed the chemical cross talk to activate the defense mechanisms against some biotic stress conditions by detection of certain key compounds.     

A DNA marker assay based on high-resolution melting curve analysis for distinguishing species of the Festuca–Lolium complex

The grass breeding industry is interested in a fast and cheap method of identifying contamination in seeds of Italian and perennial ryegrass (Lolium perenne L. and L. multiflorum Lam., respectively). This study shows that high-resolution melting curve analysis in combination with an unlabelled probe assay is an effective method of detecting single nucleotide polymorphisms (SNPs) in diverse Italian and perennial ryegrass backgrounds. This method proved efficient in differentiating ryegrass species and reducing the effect of additional DNA sequence polymorphisms close to the target SNP on the melting curve profiles. For the identification of contamination in Italian and perennial ryegrass seed production, high-resolution melting curve analysis shows great potential, as it is a single closed-tube PCR reaction with an easy workflow, providing results in <2 h after DNA extraction.     

Infection Biology of Bacterial Wilt of Forage Grasses

Infection of perennial ryegrass (Lolium perenne L.), Italian ryegrass (Loliummultiflorum L.), and timothy (Phleum pratense L.) by Xanthomonas campestris pv. graminis and Xanthomonas campestris pv. phlei occurred mainly via wounds rather than natural openings. Nevertheless, bacteria were detected by isolation and immunofluorescence in plants sprayed with the pathogen without prior wounding and in plants in which intact ears had been dipped in inocula. High concentrations of bacteria were observed around the stomata of perennial ryegrass and timothy by scanning electron microscopy 48 h after inoculation. Perennial ryegrass and Italian ryegrass and individual plants of ryegrass and timothy differedin susceptibility to the pathogens.     

Influence of preceding crop on wireworm (Coleoptera: Elateridae) abundance in the coastal plain of North Carolina

Three studies were conducted to determine the effect of preceding crop on wireworm (Coleoptera: Elateridae) abundance in the coastal plain of North Carolina. In all three studies, samples of wireworm populations were taken from the soil by using oat, Avena sativa L., baits. Treatments were defined by the previous year's crop and were chosen to reflect common crop rotations in the region. Across all three studies, eight wireworm species were recovered from the baits: Conoderus amplicollis (Gyllenhal), Conoderus bellus (Say), Conoderus falli (Lane), Conoderus lividus (Degeer), Conoderus scissus (Schaeffer), Conoderus vespertinus (F.), Glyphonyx bimarginatus (Schaeffer), and Melanotus communis (Gyllenhal). The effect of corn, Zea mays L.; cotton, Gossypium hirsutum L.; fallow; soybean, Clycine max (L.) Merr.; sweet potato, Ipomoea batatas (L.) Lam.; and tobacco (Nicotiana spp.) was evaluated in a small-plot replicated study. M. communis was the most frequently collected species in the small-plot study and was found in significantly higher numbers following soybean and corn. The mean total number of wireworms per bait (all species) was highest following soybean. A second study conducted in late fall and early spring assessed the abundance of overwintering wireworm populations in commercial fields planted to corn, cotton, peanut (Arachis hypogaea L.), soybean, sweet potato, and tobacco in the most recent previous growing season. C. lividus was the most abundant species, and the mean total number of wireworms was highest following corn and soybean. A survey was conducted in commercial sweet potato in late spring and early summer in fields that had been planted to corn, cotton, cucurbit (Cucurbita pepo L.), peanut, soybean, sweet potato, or tobacco in the most recent previous growing season. C. vespertinus was the most abundant species, and the mean total number of wireworms per bait was highest following corn.     

Winter grass cover crop effects on nematodes and yields of double cropped soybean

Rye (Secale cereale L.), wheat (Triticum aestivum L.), and annual ryegrass (Lolium multiflorum Lam.) are commonly double cropped with soybean (Glycine max L.). Recent greenhouse studies have shown variability in plant-parasitic nematode response to cool season grass species and cultivars. However, subsequent soybean performance was not affected by previous annual ryegrass cultivar in the green-house. The objective of this research was to determine whether winter cover crop species or cultivars affected nematode populations and subsequent performance of soybean in teh field. Four cultivars of annual ryegrass, wheat, and rye, and a fallow control were seeded on a Suffolk sandy loam (fine-loamy, siliceous, thermic Typic Hapuldult) soil in each of three years. Nematode-susceptible soybeans were seeded following forage removal. Soil samples for nematode counts were taken immediately before soybean harvest each year. In another experiment, one cultivar each of annual ryegrass, wheat, and rye, and a fallow control were followed by three soybean cultivars selected for differing nematode susceptibility. Grass cultivars did not affect nematode populations under succedding soybean. The only nematodes affected by grass species in either experiment were Pratylenchus spp., Heterodera glycines Ichinohe, and Tylenchorhynchus claytoni (Kofoid and White) Chitwood. Nematode population means were usually low following ryegrass and high following the fallow control. High soybean yields followed the fallow control, and low soybean yields followed annual ryegrass.     

Water Use Characteristics of Dactylis glomerata L., Lolium perenne L. and L. multiflorum Lam. Plants

Cocksfoot (Dactylis glomerata L.). perennial ryegrass (Loliumperenne L.) and Italian ryegrass (L. multiflorum Lam.) plantswere grown on deep (75–95 cm) columns of soil in glasshousesand growth rooms with and without irrigation. The species inwhich growth declined least rapidly after water had been withheldwere those which transpired most slowly. During early establishmentin the glasshouse cocksfoot transpired least because of slowroot growth. In the growth room, when root systems were deeperand denser, perennial ryegrass transpired least because of lowleaf water conductance. Results are discussed in relation to(a) drought resistance in the three species; (b) breeding forincreased drought resistance through modifying root distributionand leaf water conductance; and (c) the use of isolated soilcolumns in water relations studies. Dactylis glomerata L., Lolium perenne L., Lolium multiflorum Lam., cocksfoot, perennial ryegrass, Italian ryegrass, transpiration, roots, leaf water conductance     

Interactions of maize and Italian ryegrass in a living mulch system: (1) Shoot growth and rooting patterns

It has been demonstrated that the use of living mulches solves some of the environmental problems associated with the conventional cropping of maize (Zea mays L.). However, plant growth and yield are often reduced in such a cropping system. Since shoot competition between the main crop and the cover crop can be avoided by regular cutting of the cover crop, it was hypothesized that decreases in maize growth and yield in a living Italian ryegrass (Lolium multiflorum Lam.) mulch must be related to below ground interactions between the two species and that these may be traced back to the characteristics of their root systems. Two cropping systems, maize grown alone in bare soil (conventional cropping, BS) or together with a living Italian ryegrass mulch (LM), were studied in lysimeters (1.0 m² surface area and 1.1 m depth) placed outdoors, near Zurich Switzerland, for a duration of three years. In the LM treatment a strip, 0.3 m wide, in the center of the plot around the maize row was free of grass. For comparison, an Italian ryegrass (RG) treatment, managed as the LM treatment but without maize plants, was also included in the study. Minirhizotrons (54 mm inner diameter) were horizontally installed at ten soil depths between 0.0 and 1.0 m, perpendicular to the orientation of the maize rows. The development of the maize shoot and the rooting patterns were observed non-destructively. LM strongly modified the maize crop by decreasing growth and duration of the leaf area, and thus biomass and grain yield at harvest by as much as 78 and 72%, respectively. Maximum root densities in the three treatments were observed around the time of maize anthesis. However, BS maize was unable to build up root densities similar to those observed in Italian ryegrass plots at the time of maize sowing. The root densities of the LM and the RG treatments were usually similar. The inability of the maize plants to establish a competitive root system in the LM limits the supply of nutrients and water and therefore reduces growth and yield. Improving the productivity of maize in living mulches will depend on the ability to achieve a better separation of the rooting volumes of the two species, so that specific steps to facilitate the main crop and control the living mulch can be taken.     

The effect of atmospheric humidity on photosynthesis,transpiration and water use efficiency of leaves of several plant species

The effect of humidity on the gas exchange of leaves of the dicotyledons soybean (Glycine max (L.) Merrill), sunflower (Helianthus annuus L.), jojoba (Simmondsia chinensis (L.) Schneider), and saltbush (Atriplex halimus L.) and the monocotyledons wheat (Triticum aestivum L.), barley (Hordeum vulgare L.) sorghum (Sorghum bicolor (L.) Moench) and barnyard grass (Echinochloa crus-galli (L.) Beauv.) was examined under conditions of adequate soil moisture in a controlled environment. Photosynthesis and stomatal and internal diffusion resistances of whole, attached, single leaves were not affected by changes in humidity as the vapour pressure deficit between the leaf and atmosphere ranged from 8 to 27 mb. Transpiration increased linearly with increasing vapour pressure deficit. Whole plants of barley exhibited a different response. As humidity was increased, photosynthesis increased, transpiration expressed per unit of vapour pressure difference increased, and diffusion resistances became smaller. Reasons for the different behaviour of single leaves and whole plants are suggested. An index for water use efficiency, expressed per millibar of vapour pressure deficit, was calculated for single leaves of each species used in the experiments. This showed that water use efficiency was highest in the C₄ xerophytes and lowest in the C₃ mesophytes. The effect of environment on water use efficiency is examined using data from the literature.     

The role of endophytic bacteria during seed piece decay and potato tuberization

Healthy potato tubers (Solanum tuberosum L.) cv. Kennebec were found to be internally colonized by non-pathogenic bacterial populations originating from root zone soil. These endophytic bacteria were categorized, on the basis of bioassays, as plant growth promoting (PGP), plant growth retarding (PGR) and plant growth neutral (PGN). Genera isolated from tubers included Pseudomonas, Bacillus, Xanthomonas, Agrobacterium, Actinomyces and Acinetobacter. The PGP and PGR isolates were similarly distributed throughout these genera. Bacterial populations increased in the root zone soil directly adjacent to the seed piece during and immediately following seed piece decay. Bacteria sampled at this time were capable of promoting tuber number and weight. The proportions of PGP, PGR and PGN bacteria in the root zone were altered as endophytic bacteria were released from the decaying seed piece. The study indicates that endophytic bacteria present in the seed tubers may play an important role in seed piece decay, tuberization and plant growth.     

Interaction between C4 barnyard grass and C3 upland rice under elevated CO2: Impact of mycorrhizae

Atmospheric CO₂ enrichment may impact arbuscular mycorrhizae (AM) development and function, which could have subsequent effects on host plant species interactions by differentially affecting plant nutrient acquisition. However, direct evidence illustrating this scenario is limited. We examined how elevated CO₂ affects plant growth and whether mycorrhizae mediate interactions between C₄ barnyard grass (Echinochloa crusgalli (L.) Beauv.) and C₃ upland rice (Oryza sativa L.) in a low nutrient soil. The monocultures and combinations with or without mycorrhizal inoculation were grown at ambient (400 ± 20 μmol mol^?1) and elevated CO₂ (700 ± 20 μmol mol^?1) levels. The ¹⁵N isotope tracer was introduced to quantify the mycorrhizally mediated N acquisition of plants. Elevated CO₂ stimulated the growth of C₃ upland rice but not that of C₄ barnyard grass under monoculture. Elevated CO₂ also increased mycorrhizal colonization of C₄ barnyard grass but did not affect mycorrhizal colonization of C₃ upland rice. Mycorrhizal inoculation increased the shoot biomass ratio of C₄ barnyard grass to C₃ upland rice under both CO₂ concentrations but had a greater impact under the elevated than ambient CO₂ level. Mycorrhizae decreased relative interaction index (RII) of C₃ plants under both ambient and elevated CO₂, but mycorrhizae increased RII of C₄ plants only under elevated CO₂. Elevated CO₂ and mycorrhizal inoculation enhanced ¹⁵N and total N and P uptake of C₄ barnyard grass in mixture but had no effects on N and P acquisition of C₃ upland rice, thus altering the distribution of N and P between the species in mixture. These results implied that CO₂ stimulation of mycorrhizae and their nutrient acquisition may impact competitive interaction of C₄ barnyard grass and C₃ upland rice under future CO₂ scenarios.     

香茅天然挥发物的化感作用及其化学成分分析

在野外香茅草丛地表和密闭容器中进行了香茅天然挥发物对玉米和稗草种子萌发和幼苗生长影响的试验,并采用固相微萃取和气相色谱质谱联用技术,对香茅挥发物的化学成分进行了分析.生物测定表明,野外香茅草丛和密闭容器中香茅挥发物对玉米和稗草种子萌发率影响不显著,但对玉米和稗草幼苗的生物量、根长及苗高均产生显著抑制影响,表明香茅挥发物中存在潜在的化感物质.对挥发物的分析结果表明,根挥发物有10种成分,主要成分是长叶松烯,含量为56.67%,其次为芹子烯内酯(20.03%),其余成分含量都在10%以下.茎叶挥发物有12种成分,主要成分是柠檬醛,含量达53.98%,其次是z柠檬醛,含量为34.40%,其余成分含量都在4%以下.研究表明,在香茅挥发物中存在较多的萜类化合物,茎叶挥发物中有2个单萜,9个倍半萜,根挥发物全部为倍半萜.因此,种植香茅时不应忽视它的化感作用.