Changes in Metabolites and Allelopathic Effects of Non-Pigmented and Black-Pigmented Lowland Indica Rice Varieties in Phosphorus Deficiency

Phosphorus(P) levels alter the allelopathic activity of rice seedlings against lettuce seeds. In this study, we investigated the effect of P deficiency on the allelopathic potential of non-pigmented and pigmented rice varieties. Rice seedlings of the white variety Khao Dawk Mali(KDML105, non-pigmented) and the black varieties Jao Hom Nin(JHN, pigmented) and Riceberry(RB, pigmented) were cultivated under high P(HP) and low P(LP) conditions. Morphological and metabolic responses to P deficiency were investigated. P deficiency inhibited shoot growth but promoted root growth of rice seedlings in all three varieties. Moreover, P deficiency led to decreased cytosolic phosphate(Pi) and total P concentrations in both shoot and root tissues. The subsequent reduction in internal P concentration enhanced the accumulation of phenolic compounds in both shoot and root tissues of the seedlings. Subsequently, allelopathy-based inter-and intra-specific interactions were assessed using water extracts from seedlings of the three varieties grown under HP and LP conditions. These extracts were tested on seeds of lettuce, the weed Dactyloctenium aegyptium, and the same rice variety. The shoot and root extracts from P-deficient seedlings reduced the germination of all recipient plants. Specifically, the shoot extract from P-deficient KDML105 seedlings reduced the germination index(GI) of lettuce seeds to 1%, while those from P-deficient RB and JHN seedlings produced GIs of 32% and 42%, respectively. However, when rice seeds were exposed to their own LP shoot and root extracts, their GIs increased up to 4-fold, compared with the HP extracts. Additionally, the shoot extracts from P-deficient plants also stimulated the germination of D. aegyptium by about 2–3-fold, whereas the root extracts did not have this effect. Therefore, P starvation led to the accumulation and exudation of phenolics in the shoots and roots of rice seedlings, altering their allelopathic activities. To adapt to P deficiency, rice seedlings potentially release signaling chemicals to suppress nearby competing species while simultaneously promoting their own germination and growth.

The Combination of Achnatherum inebrians Extracts and Soil Microorganisms Inhibited Seed Germination and Seedling Growth in Elymus nutans

In a greenhouse experiment,the effects of soil microorganisms and extracts of Achnatherum inebrians on the seed germination and seedling growth of Elymus nutans were studied.The results showed that both the extracts from aboveground and belowground parts of A.inebrians significantly inhibited the germination rate,germination potential,germination index,vigor index,seedling height,root length,and fresh weight of E.nutans,but increased malondialdehyde content,catalase,peroxidase and superoxide dismutase activity of E.nutans seedlings(p<0.05).The allelopathy of aqueous extracts of the aboveground parts of A.inebrians was stronger than that of the pre-cipitates.Aqueous extracts of the aboveground parts of A.inebrians decreased seed germination rate,germination potential,germination index,vigor index,seedling length,root length,and seedling fresh weight by 10.45%-74.63%,24.18%-32.50%,19.03%-73.36%,37.83%-88.41%,21.42%-53.14%,2.65%-40.21%,and 20.45%-61.36%,respectively,and malondialdehyde content,peroxidase,catalase,and superoxide dismutase activity increased by 8.09%-62.24%,27.83%-86.47%,22.90%-93.17%,and 11.15%-75.91%,respectively.The above indexes were higher in live soil than in sterilized soil.Soil microorganisms increased the allelopathy of A.inebrians.The seed germination rate,germination potential,germination index,vigor index,seedling length,and seedling fresh weight of E.nutans planted in live soil decreased by 8.22%-48.48%,10.00%-51.85%,8.19%-53.26%,16.43%-60.03%,12.91%-28.81%,and 9.09%-22.86%compared with sterilized soil,respectively.Malondialdehyde content,peroxidase,catalase,and superoxide dismutase activity of E.nutans planted in live soil increased by 53.91%-81.06%,15.71%-57.34%,33.33%-86.31%,and 9.78%-52.51%compared with sterilized soil,respectively.The existence of soil microorganisms enhanced the allelopathy of the secondary metabolites of A.inebrians.A combination of microorganisms and aqueous extracts from the aboveground parts of A.inebrians had the strongest allelopathic effect on E.nutans.

Soybean Response to Weed Residues in the Soil

Soybean production systems that return plant residues to the soil surface are gaining in popularity. As these practices become more widespread, more crop and weed residues are being introduced into the upper soil profile. Greenhouse studies were conducted to determine the effects of varying concentrations of Palmer amaranth and pitted morningglory plant residues (aboveground portion of the plant) on soybean production. The study was arranged in a completely randomized experimental design with five treatments and five replications. Palmer amaranth and pitted morningglory residues were incorporated into soil at 20,000, 40,000, 80,000 and 160,000 ppm. Inert plastic residue at the same residue levels was included as a check. Soybean dry weight, leaf area and leaf tissue nutrient content were recorded during the study. A decrease in soybean dry weight and leaf area was observed as Palmer amaranth residue in the soil increased. Palmer amaranth residues of 160,000 ppm and 80,000 ppm in the soil significantly reduced soybean dry weight by 69% and 59%, respectively, and soybean leaf area by 60% and 57%, respectively. In contrast, pitted morningglory and inert plastic residues had no observable effect on soybean growth and development. This study demonstrated Palmer amaranth residues in the soil impacted early season soybean growth and development.

2,3-Butanediol from the leachates of pine needles induces the resistance of Panax notoginseng to the leaf pathogen Alternaria panax

Compared with the use of monocultures in the field,cultivation of medicinal herbs in forests is an effective strategy to alleviate disease.Chemical interactions between herbs and trees play an important role in disease suppression in forests.We evaluated the ability of leachates from needles of Pinus armandii to induce resistance in Panax notoginseng leaves,identified the components via gas chromatography-mass spectrometry(GC-MS),and then deciphered the mechanism of 2,3-Butanediol as the main component in the leachates responsible for resistance induction via RNA sequencing(RNA-seq).Prespraying leachates and 2,3-Butanediol onto leaves could induce the resistance of P.notoginseng to Alternaria panax.The RNA-seq results showed that prespraying 2,3-Butanediol onto leaves with or without A.panax infection upregulated the expression of large number of genes,many of which are involved in transcription factor activity and the mitogen-activated protein kinase(MAPK) signaling pathway.Specifically,2,3-Butanediol spraying resulted in jasmonic acid(JA)-mediated induced systemic resistance(ISR) by activating MYC2 and ERF1.Moreover,2,3-Butanediol induced systemic acquired resistance(SAR) by upregulating pattern-triggered immunity(PTI)-and effector-triggered immunity(ETI)-related genes and activated camalexin biosynthesis through activation of WRKY33.Overall,2,3-Butanediol from the leachates of pine needles could activate the resistance of P.notoginseng to leaf disease infection through ISR,SAR and camalexin biosynthesis.Thus,2,3-Butanediol is worth developing as a chemical inducer for agricultural production.

Do Aqueous Extracts from Buckwheat Compromise Seed Germination and Initial Development of Bidens pilosa and Euphorbia heterophylla?

Fagopyrum esculentum Moench (buckwheat) is a dicot species from the Polygonaceae family used as a cover crop in agricultural systems featured with a remarkable allelopathic potential for weed control, helping herbicide-resistance management and promoting substantial reductions in herbicide applications. The aim of this research was to examine the allelopathic potential of aqueous extracts from seeds and aerial part of buckwheat on seed germination and initial development of Bidens pilosa and Euphorbia heterophylla. Bioassay experiments were conducted under a completely randomized experimental design with four replications, containing 50 seeds each. Both weed seed species were harvested in a soybean field, and seed viability was previously assessed. Seeds were exposed to four concentrations (0, 25, 50, and 100%) from extracts of seeds (ES) and aerial part (EAP) of buckwheat. Germination speed index (GSI) in B. pilosa and E. heterophylla was daily evaluated throughout 14 and 16 days, respectively, whereas percentage of germination, abnormal seedlings, as well as non-germinated seeds, root (RL) and aerial part length (APL), and total dry matter (TDM) were rated at final germination test. EAP reduced the GSI, especially under the 100% concentration. Germination percentage was lower and abnormal seedlings increased for both weed species when seeds were exposed to EAP concentrations greater than 25%. However, ES did not impinge upon E. heterophylla germination. EAP and ES reduced the APL, RL, and TDM for concentrations greater than 50%, except for ES which did not affect E. heterophylla development. Both extracts from buckwheat have a high capacity to inhibit germination and compromise seedling development, culminating in such a potential alternative for B. pilosa and E. heterophylla management in agricultural systems.

Role of extracellular polymeric substances in resistance to allelochemical stress on Microcystis aeruginsosa and its mechanism

Using allelochemicals to suppress cyanobacteria growth is a prospective method for its high efficiency and ecological safety.However,the suppression efficiency is affected inevitably by the extracellular polymeric substances(EPS)produced by cyanobacteria,and the knowledge about the roles of EPS in resistance to allelochemical stress is scarce.For the study,two typical anti-cyanobacterial allelochemicals were adopted to investigate the role of EPS in resistance to allelochemical stress on Microcystis aeruginosa.Results show that EPS was crucial in alleviating the toxicity of allelochemicals to algae,especially in stabilizing the metabolism and photosynthetic activity of algal cells.The aggregation rate of algal cells increased with the increase of EPS secretion,which alleviated the stress of allelopathy.Tryptophan proteins and humic acids in EPS provided a binding site for allelochemicals,and the EPS-allelochemicals complex were formed by chemical bonding.This study improved our comprehension of the role of EPS in algal inhibition by allelochemicals.

蟛蜞菊根分泌物的异种克生作用及初步分离

蟛蜞菊根分泌物的异种克生作用及初步分离曾任森，林象联，谭惠芬，曾强（华南农业大学农业生态室，广州５１０６４２）（南开大学元素有机化学研究所，天津３０００７）ＡｌｌｅｌｏｐａｔｈｉｃＥｆｆｅｃｔｓａｎｄＰｒｅｌｉｍｉｎａｒｙＩｓｏｌａｔｉｏｎｏｆＲｏｏ...

Allelopathy of Aerial Part Extracts from Grafted Eggplants

[ Objective] The aim was to provide evidence and countermeasures for study on allelopathy of eggplant and supply a scientific basis for ecological management of allelopathy and establishment of a reasonable, effective intercropping and continuous cropping system. [ Method] Allelopathy of aerial part extracts from grafted eggplants was studied by bioassay. [ Result] The results showed that aerial part extracts of eggplants have autotoxiclty which inhibited seed germination and seedling growth of eggplants. Aerial part extracts of grafted eggplants inhibited seed germination and seedling growth of tomato, pepper and cu cumber at different level. Inhibition intensity of extracts was in order of tomato 〉 pepper 〉 cucumber. The inhibition effect was higher at 0.2 g/ml concentration than 0.1 g/ml concentration. There wasn＇t significance between ownrooted treatments and grafted treatments. [ Conclusion] Eggplant is not suitable for round of inter-cropping with tomato, pepper and cucumber.

Allelopathic Effects of Jatropha curcas Leaf Leachates on Seedling Gro wth and Antioxidative Enzymes in Tagetes erecta L.

[Objective] This study was to investigate the allelopathic effects of J.curcas leaf leachates on seedling growth and antioxidative enzymes,and thus to reveal physiologically allelopathic effects of J.curcas trees on undergrowth plants.[Method] The allelopathic effects of leaf leachates of Jatropha curcas amended into soil were determined on the growth,proline and malondialdehyde（MDA） contentas well as superoxide dismutase（SOD）,catalase（CAT）,ascorbate peroxidase（APX）,guaiacol peroxidase（POD） in roots of marigold（Tagetes erecta） seedlings.[Results] The application of leaf leachates of J.curcas in the soil significantly inhibited the shoot and root length of marigold compared to un-amended soils.The leaf leachates increased the O-2,H2O2,MDA and proline content in the roots of marigold seedlings.The effects increased with the ascending of leaf leachates concentration.In addition,superoxide dismutase（SOD） and guaiacol peroxidase（POD） were not remarkably affected by the leachates at lower concentrations,but at higher concentration,SOD activity was ascended.Similarly,the activities of CAT and APX were also significantly increased with the increase of leachates concentrations.[Conclusion] These results show that J.curcas can release the phytotoxic compound（s） into soil,which are inhibitory to certain test species by interfering with physiological process.

Allelopathy of decomposed maize straw products on three soilborn diseases of wheat and the analysis by GC-MS

In northern China, the soil-born diseases of wheat have been getting more and more serious under a new farming system that returns maize straw to the field. In order to investigate the allelopathy of the decomposed maize straw products on three soil-born diseases of wheat, culture dish and pot experiments were conducted and the compounds in the products were identified by gas chromatography-mass spectrometry （GC-MS）. Culture dish experiments showed that the mycelial growth, sclerotia formation amount and total weight of Rhizoctonia cerealis were promoted at concentrations of 0.03, 0.06 and 0.12 g mL-1 and inhibited at concentration of 0.48 g mL-1 of the decomposed products. No significant effects were found of the product concentrations on average weight of the sclerotia. Mycelial growth of Gaeumannomyces graminis was promoted at almost all concentrations except the highest one. Mycelial growth and spore germination of Bipolaris sorokiniana were significantly inhibited by all concentrations of the decomposed products, with enhanced inhibition effects along with the increased concentrations. The length, number and dry weight of roots together with the root superoxide dismutase activity were promoted by the lowest concentration （0.03 g mL-1）, with a synthetic effect index of 0.012, and inhibited by other concentrations. The ion leakage of roots was increased and the root peroxidase activity of roots was lowered by all the treatments. Pot experiments revealed that occurrence of the sharp eyespot was reduced by 0.03 and 0.06 g mL-1 of decomposed products after irrigation. However, the incidence rates and disease indexes were significantly increased by 0.12, 0.24 and 0.48 g mL-1 of decomposed products. The results indicated that incidence rates and disease indexes of the take-all were significantly promoted after being irrigated with the decomposed products, while occurrences of the common rot didn＇t change, significantly. GC-MS results showed that the compounds of the decomposed products included organic acids, esters, hydrocarbons, amides and aldehydes, with the proportions 25.26, 24.01, 17.22, 14.39 and 7.73%, respectively. Further analysis investigated that the allelochemicals identified in straw decomposed products contained p-hydroxybenzoic acid （9.21%）, dibutyl phthalate （6.94%）, 3-phenyl-2-acrylic （5.06%）, 4-hydroxy-3,5-dimethoxybenzoic acid （2.26%）, hexanoic acid （1.73%）, 8-octadecenoic acid （1.06%）, 3-（4-hydroxy-3-methoxy-phenyl）-2-propenoic acid （1.04%）, 4-hydroxy-3-methoxy-benzoic acid （0.94%） and salicylic acid （0.94%）.

Allelopathic effects of extracts from Solidago canadensis L. against seed germination and seedling growth of some plants

To investigate the potential role of allelopathy in plant interference and in the successful invasion of alien species Solidago canadensis, aqueous and ethanolic extracts from rhizomes, stems and leaves of S. canadensis were prepared and used as treatment solutions to assess their effects on seed germination and seedling growth in four target species, mulberry （Morus alba）; morning glory （Pharbitis nil）, wheat （Triticum aestivum） and rape （Brassiea campestris）. Reduction and/or growth in germination and growth of the target plant species in the presence of both aqueous and ethanolic extracts at different concentrations indicated that the responses were species-specific and concentration-dependent. Generally, ethanolic extracts （especially from leaves） imposed stronger effects on both seed germination and seedling growth. Extracts with lower concentration at 0.001 g/ml dw could stimulate the seedling growth of rape and morning glory, whereas extracts at any given concentrations have inhibitory effects on wheat and mulberry. It is suggested that the aqueous and ethanolic extracts of all the three parts of S. canadensis have significant allelopathic effects. Although both inhibition and stimulation occurred in the germination and growth of the target species, extracts with higher concentrations definitely inhibit seed germination and seedling growth of all target plants. We suggest that allelopathy plays a more important role than other mechanisms do in the out-competition ofS. canadensis over other plants, and make it invasive in new habitats.

Allelochemical p-hydroxybenzoic acid inhibits root growth via regulating ROS accumulation in cucumber(Cucumis sativus L.)

Allelopathy is prevalent in agricultural ecosystems and mediated by plant-derived secondary metabolites(allelochemicals).Allelochemicals are released by donor plants and affect the root growth and development of receptor plants.Allelopathy is responsible for the continuous cropping obstacles in cucumber(Cucumis sativus L.).p-Hydroxybenzoic acid(pHBA),an autotoxin from root exudates of cucumber,has been proposed to be an important allelopathic chemical.However,the molecular mechanism by which pHBA affect root growth and development in cucumber is unknown.Here,we found that pHBA treatment suppressed root growth of cucumber by reducing the meristem activity and cell length.This root growth defect is caused by reduced reactive oxygen species(ROS)accumulation in root tips.After pHBA treatment,the expression levels of several ROS-scavenging-related genes were increased,including peroxidase(POD),catalase(CAT)and metallothionein(MT).Moreover,exogenously application of salicylhydroxamate(SHAM),a peroxidase inhibitor,can partially restore the pHBA treatment induced root growth inhibition.Furthermore,we found that there is natural variation for the inhibitory effect of pHBA on root growth.We also showed that pHBA treatment could maintain higher level of ROS accumulated in the pHBA less sensitive cucumber than that in the pHBA-sensitive cucumber.These results suggest that pHBA inhibits root growth by reducing root tip ROS level in cucumber.

Effect of water extracts of larch on growth of Manchurian walnut seedlings

A study was conducted to detect the effect of water extracts from different parts such as root, bark, branch and leaf, of adult larch, Larix gmelini, trees on growth of Manchurian walnut, Juglans mandshudca, seedlings and the allelopathy between the two tree species. Four concentrations （100 g. kg i, 50 g. kg^-1, 25 g. kg^-1 and 12.5 g. kg^-1） were prepared for each kind of extracts. Result showed that the water extracts with low and moderate concentrations accelerated the growth of collar diameter and increased biomass and root/shoot ratio of walnut seedlings. The water extracts from branches and barks with low and moderate concentrations accelerated the height growth of the seedlings, while those from leaves and roots slightly decreased the height growth of seedlings. The fact that application of water extracts of larch improved the growth of Manchurian walnut attributes possibly to the allelopathy between the two tree species.

Improved single image dehazing using dark channel prior

An improved single image dehazing method based on dark channel prior and wavelet transform is proposed. This pro-posed method employs wavelet transform and guided filter instead of the soft matting procedure to estimate and refine the depth map of haze images. Moreover, a contrast enhancement method based on just noticeable difference （JND） and quadratic function is adopted to enhance the contrast for the dehazed image, since the scene radiance is usual y not as bright as the atmospheric light, and the dehazed image looks dim. The experimental results show that the proposed approach can effectively enhance the haze ima-ge and is wel suitable for implementing on the surveil ance and obstacle detection systems.

Allelopathy:Potential Role to Achieve New Milestones in Rice Cultivation

Rice fields are ecosystems with many types of plants, microbes, invertebrates, birds and animals. The rice farming protects the biodiversity of the region and maintains the ecosystem for the benefit of environment. Some rice varieties release biocidal allelochemicals which might affect major weeds, microbial and pathogenic diversity around rice plants, even soil characteristics. A large number of compounds such as phenolic acids, fatty acids, indoles and terpenes have been identified in rice root exudates and decomposing rice residues, as putative allelochemicals which can interact with surrounding environment. Since these allelopathic interactions may be positive, they can be used as effective contributor for sustainable and eco-friendly agro-production system. Genetic modification of crop plants to improve their allelopathic properties and enhancement of desirable traits has been suggested. Development of crops with enhanced allelopathic traits by genetic modification should be done cautiously, keeping in view of the ecological risk assessment(non-toxic and safe for humans and ecosystem, crop productivity, ratio of benefit and cost, etc.).

Allelopathic interactions between Prorocentrum micans and Skeletonema costatum or Karenia mikimotoi in laboratory cultures

Algal allelopathy is an ecological/physiological phenomenon that has focused attention on the interactions among algae and the production of algal toxins. We investigated the allelopathic interactions between the dinoflagellate genus Prorocentrum micans and diatom genus Skeletonema costatum and between P. micans and dinoflagellate genus Karenia mikimotoi using bi-algal cultures. Because the effects were species-specific and size-dependent, we evaluated the effect of different initial densities. At low densities of P. mieans and high densities of S. costatum inoculated into the same medium, the growth of R rnieans was weakly restrained, whereas the growth of S. costatum was significantly suppressed. S. costatum and K. mikimotoi were strongly inhibited by P. micans, in both the bi-algal cultures and enriched filtrates. Direct cell-to-cell contact was not necessary to gain a competitive advantage, thus, our results suggest that P. micans inhibited the growth of S. costatum and K. mikimotoi by the release of allelochemical（s）. Last, a mathematical model was used to simulate growth and interactions between P. micans and S. eostatum and between P. micans and K. mikimotoi in bi-algal cultures.

Allelopathic growth inhibition of Heterosigma akashiwo by the three Ulva spcieces(Ulva Pertusa,Ulva Linza,Enteromorpha intestinalis) under laboratory conditions

Allelopathic effects of several concentrations of fresh tissue,dry powder and dry tissue of three bloom-forming green macroalgae Ulva pertusa,Ulva linza and Enteromopha intestinalis on the red tide microalga Heterosigma akashiwo were evaluated in microcosms systems.The effects of macroalgae culture medium filtrate were investigated on H.akashiwo using initial or semi-continuous filtrate addition.Preliminary studies on the algicidal effects of one aqueous and four organic solvent extracts from the macroalgae on the microalga were carried out to confirm the existence of allelochemicals in the tissue of these macroalgae.The dry powder of U.pertusa was extracted with methanol,and the methanol extracts were partitioned to petroleum ether phase,ethyl acetate phase,butanol phase and distilled phase by liquid-liquid fractionation.The bioassays of the activity of every fraction were carried out on H.akashiwo.The resultant microcosms assay showed that the growth of H.akashiwo was strongly inhibited by using fresh tissues,dry powder or dry tissue of these three macroalgae,while aqueous and methanol extracts of both macroalgae had strong inhibitory effects on the growth of H.akashiwo,and the EC50 values for methanol extract of U.pertusa,U.linza or E.intestinalis were 0.016,0.028× 10-12 or 0.033× 10-12,respectively.While the other three organic solvent extracts (acetone,ether and chloroform) had no apparent effect on its growth,this suggests that the allelochemicals from these three maeroalgae had relatively high polarities.The activity of petroleum ether phase,ethyl acetate phase,butanol phase and distilled phase of U.pertusa methanol extract was carried out on H.akashiwo indicating that petroleum ether phase and ethyl acetate phase had stronger algicidal effect on H.akashiwo.The inhibition effect of the ethyl acetate phase was not as strong as that of petroleum ether phase,and effective concentration of petroleum ether phase was 17 mg/L for H.akashiwo.However,no significant algicidal effects were observed on the butanol phase and distilled water phase.These three macroalgae's culture medium filtrate exhibited no apparent growth inhibitory effect on the microalga under initial filtrate addition whereas the growth of H.akashiwo was significantly inhibited under semi-continuous filtrate addition,which suggests that continuous release of small quantities of rapidly degradable allelochemicals from the fresh tissue of both macroalgae was effective in inhibiting the growth of H.akashiwo.

Negative effects of Phaeocystis globosa on microalgae

The potential allelopathic effects of the microalga,Phaeocystis globosa Scherffel,on three harmful bloom algae,Prorocentrum donghaiense Lu,Chattonella marina(Subrahmanyan) Hara et Chihara and Chattonella ovata Hara et Chihara were studied.The growth of C.marina and C.ovata was markedly reduced when the organisms were co-cultured with P.globosa or cultured in cell-free spent medium.Haemolytic extracts from P.globosa cells in the senescence phase had a similar inhibitory effect on the three harmful bloom algae.However,P.globosa had less influence on the brine shrimp,Artemia salina.These results indicate that P.globosa may have an allelopathic effect on microalgae,which would explain the superior competitive abilities of P.globosa.Because the addition of the haemolytic toxins from P.globosa had similar effects on algae as spent media,these compounds may be involved in the allelopathic action of P.globosa.

A Preliminary Study on Allelopathy of Pogonatum inflexum Aqueous Extract

[Objective] The aim was to study the effects of Pogonatum inflexum aqueous extract on wheat seed germination and seedling growth to cladfy the possible allelopathic effects. [Method] With distilled water as control, wheat seeds were cultivated with the aqueous extract of P. inflexum gametophytes. After 7 days, the germination rate, root length, bud length, biomass and vigor index were determined. [Result] Middle and low concentration of P. inflexum aqueous extract significantly promoted the seed germination and seedling growth of wheat （P〈0.05）. With the in- creased concentration of the aqueous extract, the indexes all increased first and then decreased. The effect intensity of P. inflexum aqueous extract on root growth and biomass of wheat was stronger than that on bud growth. [Conclusion] Low-concentration P. inflexum aqueous extract promoted, while high-concentration Po inflexum aqueous extract inhibited the seed germination and seedling growth wheat.P, inflexum has a certain allelopathic potential, but the specific mechanism needs to be revealed and clarified by further research.

Effects of Exogenous Phthalic and Cinnamic Acids on Enzyme Activities and Microbial Community Structures in Rhizosphere Soil of Adzuki Bean

The aim of this study was to find out the effects of exogenous phenolic acids on soil microbes and enzymes in rhizosphere soil of adzuki bean. In the pot experiment of adzuki bean, phthalic and cinnamic acids were added at four concentrations, 0 （control）, 0.1, 1 and 10 mmol/L, to investigate the changes in the mi- croflora and enzyme activities in rhizosphere soil of adzuki bean as well as relations between them. The results showed that both phthalic and cinnamic acids could inhibit the activities of soil enzymes, including catalase, sucrase, phosphatase and urease. Higher concentrations （10 mmol/L） of phthalic and cinnamic acids showed more significant effects. In addition, the application of phthalic and cinnamic acids reduced the populations of bacteria and actinomycetes and significantly increased the population of fungi. Correlations analysis showed that phosphatase activity had an extremely significant positive correlation with bacterial population, a significant positive correlation with actinomycete population, and a significant negative correlation with fungal population. Phthalic and cinnamic acids could result in imbalanced microbe compositions, reduce enzyme activities and present evident allelopathy in rhizosphere soil.