Efficacy of Aqueous Aegle marmelos Leaf Extract for the Control of Megacopta cribraria (F.) (Hemiptera: Plataspidae)

Objective: The objective of the study is to investigate the phytochemicals and potential antibacterial activity of aqueous and ethanolic leaf extracts of Ziziphus talanai. Materials and Methods: Aqueous and ethanolic crude leaf extracts were subjected to phytochemical screening and assayed for their antimicrobial activities via paper disc diffusion method against Escherichia coli and Staphylococcus aureus. Results: Glycosides, condensed tannins, and saponins were found present in the two extracts; however, leucoanthocyanins were additionally detected in the aqueous extract. Both extracts exhibited no antibacterial activity against E. coli and S. aureus as indicated by the absence of a zone of inhibition. Conclusion: The results of the present study suggest a limited presence of phytochemicals in the crude aqueous and ethanolic leaf extracts of Z. talanai. Water can extract more phytochemicals from Z. talanai leaves than ethanol. However, the results further suggest that the phytochemicals from the leaves extracted using water and ethanol do not have antibacterial activities against E. coli and S. aureus. The negative results of the antimicrobial assay using the crude leaf extracts may not be generalized as lack of bioactivity of the other parts of Z. talanai.

This study determined the bio active substances in the physic nut plant, Jatropha curcas and further examined the larvicidal potentials of its hexane, methanol and aqueous leaf and stem extracts on locally reared larvae of the malaria vector, Anopheles gambiae in accordance with the World Health Organization’s guidelines for laboratory and field testing of mosquito larvicides. Various concentrations (25mg/mL, 50 mg/mL 100mg/mL and 200 mg/mL) of the plant extracts were tested against third instar larvae of Anopheles gambiae. Qualitative phytochemical analysis of the different portions of J. curcas leaf and stem extracts revealed the presence of active toxic compounds including alkaloids, saponins, flavonoids, glycoside and tannins. Methanolic extracts were found to be richer in phytochemicals than hexane and aqueous extracts. All plant extracts at the various concentrations showed significant larvicidal activity against Anopheles gambiae mosquito larvae between 30 minutes to 24 hours of exposure. Methanol leaf extract of J. curcas was most effective as it showed larval mortality of 75 to 100% on the test larvae after 30 minutes to 24 hours of exposure while the methanol stem extract showed 60 to 100% larval mortality. Hexane leaf extract showed larval mortality of 65 to 100% after 30 minutes to 24 hours of exposure whereas hexane stem extract had larval mortality of 60 to 100%. However, the aqueous leaf extract had 40 to 100% mortality as the aqueous stem extract showed 35 to 100% mortality after 30 minutes to 24 hours respectively. The methanol leaf extract showed highest toxicity against the test larvae with LC₅₀ value of 2.52 mg/ml; and LC₉₀ value of 218.15 mg/ml while the least toxicity was observed on aqueous stem extract with LC₅₀ value of 70.71 mg/ml; and LC₉₀ value of 1635.76 mg/ml after 30 minutes of exposure respectively. All the test larvae treated with various extracts exhibited 100% mortality after 24 hours of exposure with less concentrations of the extract required to kill the larvae as time of exposure increased. The toxicity of the various leaf extracts on the mosquito larvae were relatively greater than those of the stem. This is supported by the abundance of secondary metabolites. The findings suggest that the hexane, methanol and aqueous leaf and stem extracts of J. curcas have the potential to be used as an effective botanical larvicide.

As a result of increased interest in the production of plant-based drugs for the treatment of many diseases has become a significant reason why people have become more coversant in the use of traditional medicine for the treatment of mild and serious illness. Due to increase in the thrust for the production of plant-based drugs, this present study was carried out to compare the phytochemical constituents and antioxidant potencies of acetone, methanol and aqueous leaf extracts of Acalypha wilkesiana collected from Kaura Namoda Botanical Garden in Zamfara State-Nigeria. The antioxidant activities was evaluated using various assays; The total phenolic content of aqueous, methanol and acetone leaf extract were 15.58 0.66 mg GAE/g, 14.10 2.17 mg GAE/g and 8.70 0.01 mg GAE/g respectively. Total flavonol contents; 207.10 11.53 mg QE/g, 196.08 5.53 mg QE/g and 112.04 8.27 mg QE/g respectively. Total flavonoid contents; 240.99 9.50 mg QE/g, 252.52 3.73 mg QE/g and 123.88 5.58 mg QE/g respectively. FRAP values were 679.14 0.45 mmol/g, 611.90 7.09 mmol/g and 292.07 11.38mmol/g respectively. ABTS activity of aqueous, methanol and acetone leaf extract were 24.30 5.86 mg AAE/g, 14.49 1.02 mg AAE/g and 7.00 0.57 mg AAE/g respectively, methanol leaf extract had the highest percentage DPPH Inhibition value of 42.64 5.13, followed by aqueous (31.77 4.08) at 0.25mg/ml while aqueous had the highest (52.63 0.67), followed by methanol extract (44.80 2.80) at 0.50mg/ml. Aqueous extract had the highest percentage inhibition of Nitric Oxide with a value of 59.74 1.30, followed by methanol extract (46.11 2.54) at 0.25mg/ml. inhibition for aqueous was also highest at 0.5 mg/ml. Aqueous extract had the highest percentage lipid peroxidation inhibition value of 22.66 2.93, followed by methanol leaf extract with the value of 18.89 0.80 while at 0.50mg/ml methanol leaf extract had the highest percentage inhibition of lipid peroxidation (39.42 3.10), followed by aqueous leaf extract with the value of 31.48 1.61. The results showed that aqueous and methanol leaf extract of Acalypha wilkesiana displayed potent antioxidant effects with the aqueous having an edge. This present study therefore supports the view that Acalypha wilkesiana can be used in the management of oxidative stress and other related diseases.

ABSTRACTFicus deltoidea Jack (Moraceae) is a well-known medicinal plant used in customary medication among the Malay people to reduce and mend sicknesses such as ulcers, psoriasis, cytotoxicity, cardioprotective, inflammation, jaundice, vitiligo, hemorrhage, diabetes, convulsion, hepatitis, dysentery injuries, wounds, and stiffness. Ficus deltoidea contains a wide variety of bioactive compounds from different phytochemical groups such as alkaloids, phenols, flavonoids, saponins, sterols, terpenes, carbohydrates, and proteins. The genus Ficus has several hundreds of species, which shows excellent therapeutic effects and a wide variety of helpful properties for human welfare. Searching information was collected by using electronic databases including Web of Science, Science Direct, Springer, SciFinder, PubMed, Scopus, Medline, Embase, and Google Scholar. This review is, therefore, an effort to give a detailed survey of the literature on its pharmacognosy, phytochemistry, phytochemical, and pharmacological properties of Ficus and its important species. This summary could be beneficial for future research aiming to exploit the therapeutic potential of Ficus and its useful medicinal species.

We examined allelopathic effects and underlying mechanisms of Cinnamomum migao on its associated species Liquidambar formosana. We assessed effects of aqueous extracts of C. migao pericarp, leaf, and rhizosphere soil at different concentrations on seed germination, seedling growth, and physiology of L. formosana. All extracts inhibited L. formosana seed germination, with obvious inhibition at high concentrations (50 mg mL−1). All extracts promoted the height and ground diameter of seedlings, with the highest promotion achieved with aqueous leaf extract at a concentration of 1 mg mL−1 and aqueous pericarp and rhizosphere soil extracts at a concentration of 5 mg mL−1. All extracts promoted soluble protein accumulation in L. formosana seedlings, with the highest accumulation achieved with aqueous pericarp extracts. Aqueous leaf extract promoted soluble starch accumulation. Aqueous pericarp extract at concentrations of >10 mg mL−1 significantly increased soluble sugar content. Aqueous leaf and rhizosphere soil extracts at concentrations of >5 mg mL−1 increased proline accumulation. All extracts at concentrations of >1 mg mL−1 significantly increased malondialdehyde content. Aqueous pericarp and rhizosphere soil extracts at concentrations of 10 and 0.5 mg mL−1, respectively, promoted superoxide dismutase activity. Activities of soil urease, polyphenol oxidase, and catalase were significantly increased when the concentration of aqueous pericarp and leaf extracts exceeded 5 mg mL−1, and the activity of soil acid phosphatase significantly increased when the concentration of all extracts were 5 mg mL−1. According to the synthetic allelopathic index, the low- and medium-concentration extracts all showed a promoting effect, whereas high concentrations exhibited obvious inhibitory effects; furthermore, the comprehensive effect value of leaf water extraction was higher than that of the pericarp and rhizosphere soil. Thus, allelopathy can affect the long-term co-existence of C. migao and L. formosana.

The control of malaria relies on the use of chemical antimalarial, but the development of resistance necessitates research into alternatives. Trema orientalis (L.) Blume is used in Nigerian folklore medicine for the treatment of malaria. This study investigates the in vivo antiplasmodial activity of aqueous leaf and bark extracts of T. orientalis in rodent model. Swiss Albino mice weighing 23-27g were intraperitoneally infected with Plasmodium berghei. The lethal dose in mice was estimated to be greater than 5000mg/kg based on toxicity signs and death. Aqueous crude leaf and bark extracts were administered at 400, 800 and 1600mg/kg. Chloroquine was used as positive control while the negative control was treated with distilled water. Parasitemia, parasite inhibition, body weight and packed cell volume (PCV) were determined. The parasite inhibition of the leaf extracts at 400, 800 and 1600mg/kg was 51.55, 62.78 and 76.08% while that of the bark extract was 44.3, 65.82 and 74.23% respectively. The percentage parasitemia of the leaf extract at 400, 800 and 1600mg/kg decreased by 45.0, 70.3 and 74.7% while that of the bark decreased by 37.4, 53.0 and 52.0% respectively. The PCV of mice treated with 400, 800 and 1600mg/kg leaf extract were 48.85, 49.88 and 50.99% while that of the bark extract was 49.38, 48.88 and 51.94% respectively. The results indicate that the plant has a promising antiplasmodial activity against P. berghei, which validates its folkloric use.

The crude aqueous extracts were tested against the fourth instar larvae of Aedes aegypti (Diptera: Culicidae) at five concentrations of the technical material ranging from 12.5-200 µg/ml, including control. The bioassays were carried out in the laboratory at temperature of 29◦C ± 2 and 29.5 ± 5% relative humidity. Four replicates of each concentration of the respective toxicants in a Completely Randomised Design (CRD) were introduced with ten fourth instar larvae of Ae. Aegypti. Mortality resulting from eclosion inhibition was monitored at 3-hours interval for a period of 3, 6, 9, 12- and 24-hours post treatment. Data collected were analyzed using log-probit regression and analysis of variance. Results showed that mortality increased with increase in time and concentration and these were significantly different (P<0.05). Results indicated 65% and 87.1% mortality at the highest concentration (200 µg/ml) of the leaf and stem-bark aqueous extract respectively while the least concentration (12.5 µg/ml) resulted in 19.4% and 38.7% respectively. The LC50 values were 92.5 µg/ml and 26.5 µg/ml for the leaf and stem-bark aqueous extract respectively while the LT50 values were 29.7hr and 53.9hr respectively for the leaf and the stem-bark aqueous extract. The study suggests that Annona muricata leaf and stem-bark aqueous extract has shown promise as biopesticide for Ae. Aegypti larvae control. However, the stem-bark was found to be more effective compared to the leaf aqueous extract.

<b>Objective</b> : To investigate the comparative wound-healing potency of aqueous and methanol leaf extracts of <i> Vernonia arborea</i> Hk.<br><b> Materials</b> <b> and</b> <b> Methods</b> : Excision, incision and dead space wound models were used to evaluate the wound-healing activity of <i> Vernonia arborea</i> Hk., on Swiss Wistar strain rats of either sex. In excision wound model, treatment was continued till the complete healing of the wound, in incision and dead space wound models the treatment was continued for 10 days. For topical application, 5% w/w ointment of aqueous and methanol leaf extracts was prepared in 2% sodium alginate and for oral administration suspensions containing 30 mg/ml of each of the extracts in 1% gum tragacanth were prepared. In excision and incision wound models, the control group of animals were left untreated and in dead space wound models the animals were treated with 1 ml of 1% gum tragacanth / kg, b.w. The healing of the wound was assessed by the rate of wound contraction, period of epithelialisation, skin breaking strength, granulation strength, dry granulation tissue weight, hydroxyproline estimation and histopathology of the granulation tissue.<br><b> Results</b> : Aqueous and methanol leaf extracts promoted the wound-healing activity significantly in all the wound models studied. High rate of wound contraction, decrease in the period for epithelialisation, high skin breaking strength and granulation strength, increase in dry granulation tissue weight, elevated hydroxyproline content and increased collagenation in histopathological section were observed in animals treated with methanol leaf extract and aqueous leaf extract when compared to the control group of animals.<br><b> Conclusion</b> : Methanol and aqueous leaf extracts of <i> Vernonia arborea</i> Hk. promote wound-healing activity. Methanol extract possesses better wound-healing property than the aqueous extract.<br>

A fast-growing, evergreen tree, native to the Indian subcontinent, India, Pakistan, Myanmar, Nepal, Bangladesh, Sri Lanka, and Maldives, widely cultivated in Africa, and in southern part of Iran, but typically grown in tropical and semi-tropical regions. It is described as anti-inflammatory, analgesic, antipyretic, laxative, blood purifier, antibacterial, anthelmintic, antiseptic and wound healer. Usually, the leaves are pounded and applied to indurations and inflammations, and wounds are washed with leaves boiled in water, and also powdered leaves are sprinkled on wounds. Dried flowers are used as a tonic after fever. Leaves are used in the traditional Nigerian medicine in the treatment of diabetes, and by the native healers for the treatment of malaria in Meru and Kilifi Districts of Kenya and Cote d’Ivoire. Neem contains more than 35 biologically active principles; azadirachtin is the predominant insecticidal active ingredient in seed, leaves, and other parts of neem tree. Nimbidin, azadirachtin and nimbinin are reportedly the active compounds responsible for its antibacterial activity. Freshly prepared juice of green leaves, macerated in water, daily for one month to male mice reduced number of pregnancies and the litter size, which returned to normal after 6 weeks of drug free interval, and crude aqueous leaf extract to male rats for 10-weeks caused a significant decrease in serum testosterone levels, and to mice for 4-weeks produced reversible but appreciable antiandrogenic effects on male reproductive organs. Hydroalcohol leaf extract possesses significant blood sugar-lowering activity in normal and diabetic rats, and aqueous leaf extract highly significantly lowered FBG, reduced oxidative stress and increased levels of GSH and SOD of diabetic rats. Aqueous leaf extract is also an effective in vitro aldose reductase inhibitor, potentially able to reduce cataractogenic effect of diabetes. Freshly prepared, and dried leaves aqueous extracts produced significant anxiolytic effects, improved memory and spatial learning in rats with experimental Alzheimer’s disease, and significantly reduced cerebral hypoperfusion-induced functional disturbances in rats. Leaf aqueous extract treatment of Nigerian patients with malaria also lowered serum TC and LDL-C, and significantly increased triacylglycerol and HDL-C. Neem mouthwash inhibited growth of S. mutans, reduced plaque-induced gingivitis, and reduced ability of some Streptococci to colonize tooth surfaces, and the gel application significantly reduced the plaque index and bacterial count.

The anthelmintic efficacy of the aqueous extracts o neem (Azadirachta indica) leaf and stem and root barks against the hatching of eggs and the survival of larvae of nematode parasites of small ruminants were studied. The results of the in vitro egg hatch assay showed that the aqueous extracts of the leaf and stem bark produced significant anthelmintic effect through reduction in nematode egg hatch. The reduction in egg hatch was concentration dependent being highest (51 % and 50 % for the leaf and stem bark extracts respectively) at the highest concentration (100 mg/ml) of the extracts but inferior to those produced by albendazoe (100 % at 40 mg/ml). Aqueous extracts of the leaf and root bark produced significant reduction in larval survival within 60 minutes at ambienttemperature (30 – 35 ºC). Larval death was similar in both extracts and concentration dependent, increasing with increasing concentration of the leaf and root bark extracts. The reduction in larval survival due to the extracts was similar to that produced by albendazole. In general, the aqueous extract of neem leaf was more efficacious in limiting nematode larvae survival and in-vitro egg hatch. The results confirm the folkloric claims that neem has anthelmintic effect and thus suggest its possible usefulness as an anthelmintic. Keywords: Anthelmintic efficacy, Aqueous extract, Leaf, Stem, Root, Bark, Azadirachta indicaAnimal Research International Vol. 3 (3) 2006 pp. 549-552

Aims: The study was conducted to evaluate the phytochemical and antioxidant potentials of ethanol and aqueous leaf extracts of Simarouba glauca vis-a-vis standard antioxidants. Study Design: True experimental study. Place and Duration of Study: Department of Biochemistry, University of Benin, Benin City. Nigeria, between August and October 2015. Methodology: Samples were harvested, air dried, pulverized and extracted with aqueous and absolute ethanol; freeze dried at the National energy commission centre, University of Benin. Total phenol content was determined by Folin-ciocalteau method, tannin determined according to Folin and Denis methods while flavonoids content was determined according to the methods described by Ebrahimzadeh et al. DPPH radical scavenging activity was conducted based on the ability of 1,1-diphenyl-2-picrylhydrazyl (DPPH), a stable free radical, to decolorize in the presence of antioxidants. Reducing power activity of extracts was conducted based on test samples extract’ Original Research Article Osagie-Eweka et al.; EJMP, 13(3): 1-11, 2016; Article no.EJMP.24736 2 ability to reduce ferricyanide to ferrocyanide indicated in the colour change. Total antioxidant activity of ethanol and aqueous leaf extracts was determined based on the ability of the sample to reduce the ferric-tripyridyltriazine (Fe (III)-TPTZ) complex to ferrous tripyridyltriazine (Fe(II)-TPTZ) at low pH. Hydroxyl radical activity of extracts was conducted on the principle based on the ability of test samples to reduce H2O2 in the presence of 1,10-phenanthroline. Trolox equivalent antioxidant activity of extracts was conducted based on the ability of test sample to scavenge 2,2’azinobis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical generated based on the principle of decolourization. Nitric oxide (NO.) radical scavenging activity of S, glauca leaf extracts was estimated based on the ability of test samples to scavenge radicals generated by the reaction of naphthylethylenediamine dihydrochloride. Butylated hydroxytuolene (BHT), Ascorbate, Quercetin and Trolox were standard antioxidant. Results: DPPH radical scavenging activity yielded aqueous and ethanol extracts IC50 values of 3.2144 and 4.9100 μg/ml respectively. Reducing power activity yielded (aqueous and ethanol extracts) EC50 of values 60.3233 and 60.1000 μg/ml respectively. Total antioxidant activity yielded (ethanol and aqueous extracts) IC50 values of 52.4320 and 68.8201 μg/ml respectively. Hydroxyl radical activity yielded (ethanol and aqueous extracts) IC50 values of 49.3130 and 50.2341 μg/ml respectively. Trolox equivalent antioxidant activity yielded (ethanol and aqueous extracts) IC50 values of 45.2015 and 52.0721 μg/ml respectively. Nitric oxide scavenging activity yielded aqueous IC50 value of 14.2102 μg/ml but ethanol extract yielded no inhibition concentration at 50 percent. Conclusion: The study showed that aqueous and ethanol leaf extracts of S. glauca demonstrated substantial amount of biochemically valuable phytochemicals and antioxidant potential capable of scavenging reactive oxygen species.

Background: Bauhinia tomentosa L. leaves, flower buds or root had been reported to possess anti-diabetic, anti-pyretic, antioxidant, anti-proliferative properties. The seeds and bark of the plant had not still studied for their anti-bacterial properties despite their uses in traditional medicines. Methods: Solvent extraction method was used to prepare crude aqueous, methanol and ethanol extracts of leaf, seed and bark, used for phytochemical screening to determine the classes of metabolites present. Anti-bacterial activity of leaf, seed and bark extracts was evaluated using agar well diffusion assay. Minimum inhibitory concentration (MIC) of extracts was examined using broth dilution assay. Result: Qualitative phytochemical analysis of aqueous seed extract revealed the presence of maximum number of phytochemicals (alkaloids, glycosides, flavonoids, phenols, saponins, tannins, terpenoids and amino acids). Aqueous and methanol seed extracts were observed to be effective against all the tested bacteria viz. Enterobacillus, Micrococcus, Klebsiella pneumoniae, Streptococcus thermophilus and Haemophilus influenza. On the other hand, all the leaf extracts (ethanol, methanol and aqueous) showed inhibition against Enterobacillus, Micrococcus, S. thermophilus and H. influenzae except K. pneumoniae. The aqueous extracts of seed, leaf and bark was observed to be more potent against all the Gram positive and Gram negative bacteria followed by methanol extracts of leaf and seed.

The effect of different concentrations of Cassia alata crude aqueous leaf extract on the germination ofCorchorus olitorius was investigated. All concentrations of C. alata aqueous leaf extract (10, 30, 50, 75 and 100% C) used in this study caused significant (P < 0.05) decrease in the total percentage and germination rate of C. olitorius. Similarly, all concentrations of this extract significantly (P < 0.05) inhibited radicle elongation in C. olitorius. Pre-soaking of C. olitorius seeds in C. alata crude aqueous leaf extract led to an increase in the lag-phase period preceding germination of the seeds in a concentration-dependent manner. The total percentage and rate of germination decreased as extract concentration increased. All concentrations caused a consistent decrease in absolute rate and percentages of germination compared to the control. Key words: Cassia alata, Corchorus olitorius, aqueous extract, germination.

Pesticidal plants offer valuable and sustainable options for managing Lepidopteran pests with considerable health, environmental and economic benefits in smallholder agro-ecosystem. This study Biopesticidal properties of aqueous crude extracts of tobacco (Nicotiana tabacum L.) against fall armyworm (Spodoptera frugiperda J.E Smith) on maize foliage (Zea mays L.) diets. Bio-efficacy of aqueous crude N. tabacum leaf extracts was evaluated under average room temperature at Great Zimbabwe University, Biology laboratory. The treatments were tobacco leaf extracts at four dosage levels (25 %, 33.33%, 41.67 % and 50% W/V ) and a negative control of untreated maize leaf foliage (distilled water) was used. A positive control of Carbaryl 85% WP was also used at label rates. The experiment was arranged in a Complete Randomized Design (CRD) replicated three times. Five larvae were placed into each of the experimental jars with maize foliage diets drenched into 10ml of distilled water in each treatment extract to keep the maize leaf foliage moist. Mortality for each treatment was recorded at 2 hourly intervals for 20 hours. Results showed that tobacco crude aqueous leaf extracts had Antifeedent activities against FAW larvae. The highest dose of 50% had significantly higher mean FAW larval mortalities (p&lt; 0.05) than lower dosage (25%) and the negative control after 20 hours. However, 50% concentration was not significantly different (p&gt;0.05) from the positive control and that of 33.33% and 41.67% dosages. The bioassay indicated that the 33.33% extract was superior in toxicity to 25% dose and the negative control but similar to higher extract doses though inferior to positive control. However, the mean mortality of 50% extract was not significantly different (p&lt;0.05) from that of the positive control. This study recommends that 50% tobacco aqueous crude leaf extract dose to be used when controlling FAW in maize in the smallholder sector.

Through the outdoor potted plant trials, the allelopathic potential of Populus tomentosa was tested against its species in the growth, chlorophyll content, and photosynthetic and chlorophyll fluorescence characteristics with aqueous extracts (0.01, 0.02, 0.05, and 0.1 g·mL−1) obtained from leaves at different individual ages (1, 20, and 45 years old). The results showed that seedling height, basal diameter, fresh and dry weights, quantity of chlorophyll, the ratio of chlorophyll a/b, net photosynthetic rate (P n ), stomatal conductance (G s ), transpiration rate (T r ), efficiency of primary conversion of light energy of PSII (F v /F m ), potential activity of PSII (F v /F 0), and photochemical quenching (q P ) of the seedlings gradually decreased with the increase of extract concentration of all three ages when compared with the controls. The older the P. tomentosa used for extract preparation, the greater the percentage declined in the aforementioned parameters. Moreover, at the four concentrations used, there was a significant difference between treatments with the extracts from 1- and 45-year-old plants (except for q P ), but occasionally, the effects were not obvious between the 1- and the 20-year-old plants, or the 20- and 45-year-old plants. The intercellular CO2 concentration (C i ) treated with the extracts from the 1-year-old decreased at the lowest concentration, whereas it increased at higher concentrations. The C i treated with aqueous leaf extracts from the 20-year-old decreased at the lower concentrations and increased to similar levels to that of the control at the higher concentrations. C i was always close to control levels in 45-year-old extract treatments. All the aqueous leaf extracts of P. tomentosa at all ages caused an increase of the initial fluorescence (F 0 ). The older P. tomentosa used for the preparation of aqueous leaf extracts caused a greater percentage decline in F 0 . The nonphotochemical quenching (q N ) increased significantly at lower concentrations of all P. tomentosa extracts, whereas it decreased significantly at higher concentrations. It seemed that aqueous leaf extracts from P. tomentosa were harmful to the photosynthetic structure of its own seedlings, inhibited seedling growth, and led to an eventual decrease of biomass. Extracts from older P. tomentosa leaves had more negative effects on the seedling growth of poplar. The effects on photosynthesis are the more important mechanism of the allelopathy of poplar.