International Journal of Basic and Applied Sciences, 4 (4) (2015) 381-394 www.sciencepubco.com/index.php/IJBAS ©Science Publishing Corporation doi: 10.14419/ijbas.v4i4.5147 Research Paper Determination of allelopathic potentials in plant species in Sino-Japanese floristic region by sandwich method and dish pack method Kwame Sarpong Appiah 1, Zhenhao Li 1, Ren-Sen Zeng 2, 3, Shiming Luo 2, Yosei Oikawa 1, Yoshiharu Fujii 1 * 1 Department of International Environmental And Agricultural Science, Tokyo University of Agriculture and Technology, Japan 2 Institute of Tropical and Subtropical Ecology, South China Agricultural University, China 3 College of Crop Science, Fujian Agriculture and Forestry University, China *Corresponding author E-mail: yfujii@cc.tuat.ac.jp Copyright © 2015 Kwame Sarpong Appiah et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract The Sino-Japanese Floristic Region appears as one of the major centers of development of higher plants. This region have been relevant for the study of evolution and systematics of many flowering plants. The taxonomic richness of endemic plant species in this region have survived several years of extreme climate conditions. Endemic mountainous plant species that have survived extreme climate conditions are of allelopathic and medicinal interest. For this reason, 251 plant species collected from the Sino-Japanese Floristic Region were screened for allelopathic plant species. Sandwich method and dish pack method were respectively used to screen plant leaf leachates and volatile materials with lettuce (Lactuca sativa CV. Great Lakes 366) as receptor plant. Among the 84 species that showed inhibitory effect on lettuce radicle elongation in our sandwich bioassay, Photinia glabra showed complete inhibition of lettuce radicle elongation (0% radicle elongation). In the dish pack bioassay, Photinia glabra, Liquidambar styraciflua, and Cinnamomum camphora (90.6%, 61.4%, and 50.2% respectively) were among the nine species that were observed with strong inhibitory effect on lettuce radicle growth. On the other hand, nine other species promoted lettuce radicle growth when compared to the control. Aesculus turbinata and Quercus gilva were the species with the highest growth stimulatory effect (33.0% and 16.1% respectively). We hereby present Photinia glabra as an allelopathic candidate species for both leachate and volatile compounds. Keywords: Allelochemicals; Dish Pack Method; Elongation; Leaf Leachates; Sandwich Method; Sino-Japanese Floristic Region. 1. Introduction Some living organisms especially plants, have the inherent ability to interfere with biological activities of other organism(s) in their immediate vicinity by releasing certain compounds, this phenomenon is termed as allelopathy. The term allelopathy describes beneficial and mostly harmful natural interactions between organisms due to the release of bioactive secondary metabolites from the donor organism. These secondary metabolites associated with this phenomenon are called allelochemicals which are mostly introduced into the environment through volatilization, leaching, root exudation, and/or by the decomposition of plant residues [1]. Majority of allelochemicals are products of secondary metabolism with a few resulting from primary metabolism [2]. From an ecological perspective, allelopathy may play an important role in the process of biological invasion. Some invasive plant species are perceived to be successful because they possess novel compounds that function as allelopathic agents or as mediators of the new plantplant interactions [3]. Some effects of allelochemicals on the growth and development of susceptible plants include; reduced radicle and shoot extension, darkened and/or swollen seeds, curling of root axis, discoloration of seeds, lack of root hairs, necrosis, increased number of seminal roots, and reduced dry weight accumulation among others [4]. Modern agricultural practices have succeeded due to the discovery and adoption of agrochemicals for pest control. However, there have been 452 unique cases of herbicide resistant/tolerant weeds among 245 species [5]. Nonetheless, it is difficult 382 International Journal of Basic and Applied Sciences to estimate the cost associated with yield losses due to only herbicide-resistant/tolerant weeds [6]. Due to the increasing number of herbicide-resistant/tolerant weeds and environmental concerns about the inappropriate use of synthetic herbicides, efforts have been made towards developing alternate sustainable weed management strategies. Plants that are able to suppress and/or eliminate competing plant species have received much attention, and the possibilities of using compounds from such plants as selective natural herbicides have increased [7, 8]. Isolated bioactive substances (allelochemicals) from plants are therefore important sources for alternate agrochemicals which could help reduce some of the problems arising from poor cultural practices and excessive use of synthetic pesticides [9]. These natural agrochemicals, compared to their synthetic counterparts are expected to have shorter half-lives in the environment and hence considered to be more environmentally friendly [10]. Over the last decade, there have been a growing market for products from organic farming [11]. Consequently, current researches in weed management have focused much attention on the use of natural products (allelochemicals) as natural pesticides in order to reduce the effects of synthetic pesticides on environment and human health, and to promote sustainable agriculture [12]. These have called for the screening for growth inhibitory plants and the subsequent isolation of their active compounds. This study focused on plants in the Sino-Japanese Floristic Region in East Asia which have one of the most diverse temperate floras in the world. The flora of this region holds special interest for the study of the history of temperate floras of the northern hemisphere. Several plant species of different genera have been reported to be endemic in this region [13]. Qian, [14] reported that the taxonomic richness of seed plants of East Asia is significantly more diverse compared to North America with approximately twice as many plant species as eastern North America, which holds similar size and environment. High physiographical heterogeneity is considered to be of major influence on the extremely high floral diversity within the Sino-Japanese Floristic Region [15]. During the exceptionally cold periods of climate change, the series of mountains (usually with elevations of about 2000 m) in this region provided diverse habitats allowing for species survival. Cool environments at higher elevations are suitable for survival of relict populations in modern subtropics. These relict population may however had allowed for the divergence between extant populations [16]. Recently, the allelopathic potential of certain plant species especially those with medicinal properties have been reported. In this study, we present the comprehensive screening of allelopathic activity of some plants in this region using the sandwich and dish pack methods. The basis of current weed control researches towards identifying potent bioactive compound(s) for weed control is the screening of large quantities of plants. Potential allelopathic candidate species would be identified from the screening process to pave way for further researches. We examined 256 plant samples from 251 different plant species for their allelopathic potentials under laboratory conditions. This report only focused on identifying and introducing allelopathic potentials in some plant species of Sino-Japanese region, while another report will focus on the identification of allelopathic compounds in species that exhibited strong allelopathic potentials for growth inhibitors. 2. Materials and methods 2.1. Plant samples and preparation The collection of plant samples focused on a part of Japan and China called the Sino-Japanese Floristic Region. A total of 256 plant samples were collected from seven different locations; including the campus of Tokyo University of Agriculture and Technology (TUAT), Tsukuba Botanical Gardens (TKBG), Tokyo Medicinal Botanical Garden (TMBG), Wuhan Botanical Garden (WHBG), Kunming Botanical Garden (KMBG), South China Botanical Garden, (SCBG), and South China University of Agriculture (SCUA). The leaves and other parts of each plant species were freshly collected, placed in separate paper bags and oven-dried (60℃ for 24 hours). The samples were then kept in an air-tight box until further use. The oven-dried samples were used for laboratory studies in the Laboratory of International Agro-Biological Resources and Allelopathy at Tokyo University of Agriculture and Technology, Japan. 2.2. Sandwich method The sandwich method adopted from Fujii et al., [17] was used to determine the allelopathic activity of leachates from selected donor plant leaves. This method have been used [18, 19, 20] to screen large quantity of plants and is effective in determining allelopathic activities by plant leachates under laboratory conditions. Using this method, 251 plant samples (245 species) were screened. Using multi-well plastic dish, the sandwich method was set up as shown in Fig. 1. Treatments were replicated three times and data presented as the mean of the three replicates. Agar with no plant material was set as the untreated control. The multi-well plastic plates were completely randomized in an incubator (NTS Model MI-25S) at 25°C for three days after which radicle and hypocotyl lengths were measured. 2.3. Dish pack method Fujii et al., [21] adopted this approach to screen for the presence of volatile allelochemicals from plant species. This method is widely used [22] because it determines the presence of volatile allelochemicals in plants very quickly. Using International Journal of Basic and Applied Sciences 383 this method, 69 plant species were screened for possible volatile substances that can influence (promote or inhibit) the growth of lettuce. Multi-well plastic dishes with 6 wells (36 mm×18 mm each) were used in this experiment. The distances from the center of the source well (where plant sample was placed) to the center of other wells were 41, 58, 82, and 92 mm (Fig. 2). The source well was filled with 200 mg of oven-dried plant material, while filter papers were laid in the other wells and 0.75 ml of distilled water was added to each of the wells containing filter paper. The control treatment did not contain any plant sample at the source well. Seven lettuce seeds (Lactuca sativa var. Great Lakes 366) were placed on the filter paper in each well. The multi-well dishes were tightly sealed using cellophane tape to avoid desiccation and loss of volatile compounds. To exclude light, aluminum foils were wrapped around the dishes and placed in an incubator (NTS Model MI-25S) at 25°C for three days. The radicle and hypocotyl lengths were measured and recorded after 3 days of incubation and compared to that of the control. The degree of inhibition were estimated by the relationship between lettuce seedling growth inhibition and its distance from the source well. Fig. 1: Sandwich Method: (A) Multi-well plastic plate with six wells; (B) 10 Or 50 mg dried plant material placed in each well of the multi-well plastic plate; (C) Addition of 5 mL plus 5 mL agar (Nacalai Tesque Agar Powder, 0.75% w/v autoclaved for 20 minutes at 120°C) in two layers on the oven-dried plant material; (D) Five seeds (Lactuca Sativa Var. Great Lakes 366) Lettuce seeds vertically placed; (E) Covered with plastic tape and appropriately labelled the multi-well plastic plates for incubation in dark conditions [17]. Fig. 2: View from top of Multi-well plastic plate used to test for plant allelopathy through volatile substances. 2.4. Statistical analysis The experimental set-up was arranged in a complete randomized design with three replicates. In the statistical analysis, evaluation of the means, standard deviation (SD), and SD variance (SDV) were done using Microsoft Excel 2007. Elongation % = (Average length of treatment radicle/hypocotyl) (Average length of control radicle/hypocotyl) (1) Inhibitory % =100 - (Average length of treatment radicle/hypocotyl) (Average length of control radicle/hypocotyl) (2) 3. Results 3.1. Allelopathic effects of leachates from oven-dried plant materials on lettuce The percentage elongation of radicle and hypocotyl of lettuce seedlings (1) as affected by leachates from 245 plant species based on sandwich method is shown in Table 1. In this study, the radicle elongations percentages of lettuce 384 International Journal of Basic and Applied Sciences seedlings were in the range 0-123% and 0-105% of the untreated control when respectively treated with 10 mg and 50 mg of oven-dried leaves. In both 10 mg and 50 mg of oven-dried leaf treatment, lettuce radicle elongations were inhibited more than hypocotyl elongations. With respect to 10 mg oven dried leaves treatment, it was observed that 84 species caused significant inhibition on lettuce radicle as evaluated using standard deviation variance (SDV). The families with the highest number of different plant species examined were Magnoliaceae (16 species), Rosaceae, and Fabaceae (11 species each), Fagaceae (8 species) with Oleaceae, Moraceae, and Araliaceae have 7 species each. Only the Rosaceae and Amaryllidaceae families had two species that had lettuce radicle elongation less than 29% of control with Anacardiaceae and Malvaceae having one species each. Further, Boraginaceae, Alistolochiaceae, Euphorbiaceae, Berberidiaceae, Taxaceae, Magnoliaceae, Hemerocallidaceae, and Rutaceae (one species each) showed lettuce radicle elongation in the range 29.5-39.8% of control. It was also found that the oven-dried leaves of six species showed the strongest inhibitory activity on lettuce seedling, showing radicle elongation in the range of 0-29% of the untreated control for 10 mg treatment. These species include; Photinia glabra, Dracontomelon duperreanum, Hibiscus syriacus, Amygdalus persica, Lycoris aurea, and Lycoris radiata. Eight other species (Cordia dichotoma, Asarum nipponicum, Bischofia polycarpa, Mahonia lomariifolia, Taxus wallichiana, Magnolia liliiflora, Hemerocallis fulva, and Acronychia pedunculata) showed strong inhibitory activity on lettuce seedling with radicle elongation in the range of 29.5-39.8% of the untreated control for 10 mg treatment. In lettuce radicle elongation of 38.9-50.2% of the untreated control, 18 different species were observed when treated with 10 mg oven-dried leaves. The lowest inhibitory activity in this study was observed in 52 plant species with lettuce radicle elongation for 10 mg treatment in the range of 50.3-60.6% of the untreated control. In terms of inhibition on lettuce hypocotyl elongation, only two species P. glabra and A. persica (both Rosaceae) could cause the strongest reduction (˂29.5%) in this study. Among the 251 plant samples evaluated, only P. glabra could completely reduce both lettuce radicle and hypocotyl elongations to 0% for both 10 mg and 50 mg oven-dried leaves treatment. Photinia glabra (Rosaceae) was ranked the strongest inhibitory plant species among the evaluated species using the sandwich method. 3.2. Effects of volatiles compounds from plant species on lettuce seedlings in dish pack method Table 2 shows the effects (inhibition or promotion) on radicle and hypocotyl of lettuce seedlings that were grown in dish packs containing oven-dried leaves from 69 different plant species. The effects of the plant leaves on growth of lettuce radicle and hypocotyl (2) were presented either as promotion or inhibition. Lettuce radicle growth values indicated negative represent promotional effect when compared to the corresponding control. Our results indicate that among the 69 plant species tested, lettuce radicle growth was either inhibited or stimulated by 9 different species each when compared to the control. Strongest inhibitory effects were shown in seven families, including Rosaceae (two), Taxadiaceae (two), with Altingiaceae, Lauraceae, Pinaceae, Rubiaceae, and Juglandaceae having one species each for different plant species. Only Photinia glabra was observed among the 69 plant species tested to have inhibited lettuce radicle growth more than 90%. It was also observed that two other species (Liquidambar styraciflua and Cinnamomum camphora) showed lettuce radicle growth inhibition in the range of 50-62%. Six other species including, Metasequoia glyptostroboides, Sciadopitys verticillata, Amygdalus persica, Pinus parviflora, Platycarya strobilacea, and Gardenia sootepensis demonstrated lettuce radicle inhibitory effect in the region of 31-39%. Moreover, Aesculus turbinata showed stimulatory effect on lettuce growth more than 25%, whereas Quercus gilva, Diospyros kaki, Prunus buergeriana, Cephalotaxus fortunei, and Fraxinus longicuspis demonstrated lettuce growth stimulation in the range of 10-24%. Polyalthia longifolia, Magnolia obovata, and Acer mono, showed the least stimulatory effect (6.0-9.8%) on lettuce radicle growth. 4. Discussion Our study indicated that among 251 plant species studied, 10 species showed very strong inhibitory activity on radicle and hypocotyl lengths of lettuce seedling. Currently, there have been no allelopathic reports on six of these species (Photinia glabra, Liquidambar styraciflua, Hibiscus syriacus, Lycoris aurea, Cordia dichotoma, and Asarum nipponicum). Nonetheless, these plants contain some phytochemicals that are linked to phytotoxicity and the inhibition effects observed in these plant species may be due to these compounds or some unknown chemical constituents. We however introduce these compounds in this report. Another report will focus on the identification of bioactive compounds with allelopathic capabilities associated with some of these plant species. Among the species of the Rosaceae family in this study, Photinia glabra had the greatest inhibition on lettuce radicle growth in both sandwich and dish pack methods. P. glabra is native to Japan and have been widely planted for its attractive bright-red new leaf growth and grows 15 to 20 feet in height [23]. The leaves of P. glabra produced two biphenyl compounds when inoculated with fungal spores and treated with HgCl2. These two biphenyl compounds (2’-methoxyaucuparin and 4’methoxyaucuparin) are reasoned to be produced in response to microbial attack [24]. These phytoalexins from P. glabra and other plant species from the Rosaceae family can inhibit several pathogens especially fungi but their usefulness are however still limited [25]. Hirai et al., [26] reported that plants in the Rosaceae family contain sorbitol which is synthesized from glucose-6-phosphate during photosynthesis in the leaves of these plants. Ishikura, [27] reported that the fruits of P. glabra contain anthocyanin identified as cyaniding 3-monoglucoside. International Journal of Basic and Applied Sciences 385 Table 1: Radicle and hypocotyl elongation percentages of lettuce seedlings grown on agar gel containing oven-dried plant materials tested using the sandwich method. Plant families POC Scientific Name Acanthaceae WHUN WHUN TUAT TUAT TUAT TUAT TUAT WHUN TSUK TSUK TSUK TUAT WHUN SCBG WHUN SCBG SCBG SCAU KUMN SCBG Adhatoda vasica Nees Gendarussa vulgaris Nees Acer pictum Thunb. Acer buergerianum Miq. Acer cissifolium K. Koch Acer palmatum Thunb. Acer diabolicum Blume ex K. Koch Acorus gramineus Aiton Actinidia arguta Franch. & Sav. Actinidia rufa Franch. & Sav. Asarum nipponicum F. Maek. Liquidambar styraciflua L. Lycoris radiata Herb. Lycoris aurea Herb. Spondias lakonensis Pierre Dracontomelon duperreanum Pierre Artabotrys hexapetalus (L. f.) Bhandari Polyalthia longifolia (Sonn.) Thwaites Peucedanum decumbens Maxim. Alstonia scholaris (L.) R. Br. Tabernaemontana divaricata (L.) R. Br. ex Roem. & Schult. Wrightia pubescens R. Br. Ilex ferruginea Hand.-Mazz. Ilex crenata Thunb. Ilex rotunda Thunb. Ilex integra Thunb. Livistona fengkaiensis X. W. Wei & M. Y. Xiao Alocasia macrorrhizos (L.) G. Don Pothos chinensis (Raf.) Merr. Acanthopanax sessiliflorus Seem. Schefflera octophylla Harms Hedera rhombea Siebold & Zucc. Aralia cordata Thunb. Acanthopanax simonii C. K. Schneid Aralia elata (Miq.) Seem. Hedera nepalensis K. Koch Rhapis excelsa (Thunb.) A. Henry Arenga tremula Becc. Caryota urens L. Areca triandra Roxb. ex Buch.-Ham. Arenga pinnata Merr. Hosta sieboldiana (Hook.) Engl. Asparagus albus L. Ligularia fischeri Turcz. Chrysanthemum japonicum (Maxim.) Makino Aster ageratoides Turcz. Chrysanthemum pacificum Nakai Stevia rebaudiana Bertoni. Mahonia lomariifolia Takeda Nandina domestica Thunb. Mahonia fortunei hort. ex Dippel Betula platyphylla Sukaczev Mayodendron igneum Kurz Aceraceae Acoraceae Actinidiaceae Aristolochiaceae Altingiaceae Amaryllidaceae Anacardiaceae Annonaceae Apiaceae Apocynaceae SCBG Aquifoliaceae SCBG SCBG TUAT SCBG TUAT Arecaceae SCBG Araceae SCBG WHUN WHUN SCAU TUAT TSUK KUMN TSUK WHUN SCBG SCBG SCBG SCAU SCBG TSUK WHUN TSUK Araliaceae Arecaceae Asparagaceae Asteraceae TSUK Berberidaceae Betulaceae Bignoniaceae TSUK TSUK TSUK KUMN TSUK SCBG TUAT SCBG Dry leaf content (10 ml agar-1) 10 mg 50 mg R% H% R% H% 55.6 115 24.2 91.2 62.2 145 22.9 80.0 55.2 92.6 26.1 83.3 59.5 105 22.2 70.8 61.5 88.2 16.2 43.2 67.4 87.5 27.2 85.8 83.9 120 26.8 81.1 59.3 126 20.1 67.7 65.6 83.8 46.7 123 88.1 111 35.0 87.1 33.6 82.9 16.7 76.3 83.5 114 59.1 95.8 26.3 92.0 8.70 35.2 23.2 72.5 0.0 0.0 72.8 101 50.0 73.0 13.1 40.4 12.6 44.8 58.1 84.2 28.3 69.0 76.0 123 31.1 118 64.4 91.4 41.6 78.5 52.1 91.9 29.9 87.6 Criteria * * * * *** **** **** ***** * * 58.1 91.2 31.3 65.5 * 73.2 56.2 76.3 96.3 98.6 109 110 127 175 120 49.5 35.5 75.4 51.2 78.2 97.1 84.9 124 111 122 56.0 97.5 42.3 80.4 * 60.6 47.6 46.4 65.9 67.2 107 73.2 86.5 60.4 61.1 82.9 95.3 114 71.2 43.3 105.3 50.2 122 107 116 130 109 164 91.4 109 106 94.7 109 129 123 94.7 59.2 134 88.3 52.0 19.5 24.4 21.9 36.3 48.0 59.8 27.1 29.4 30.8 64.1 91.7 94.0 43.9 34.4 89.0 26.7 115 51.3 75.4 59.6 86.8 151 81.5 86.5 105 72.4 111 149 125 75.9 58.8 135 64.9 * ** ** 71.8 106 24.0 51.5 85.3 50.9 111 35.1 47.3 54.8 83.7 56.0 110 102 113 67.2 68.9 76.6 104 90.3 65.2 73.3 53.3 26.8 26.2 29.9 65.2 28.0 103 104 113 53.8 47.4 81.4 108 82.5 * * ** * * *** ** * * 386 International Journal of Basic and Applied Sciences Plant families POC Scientific Name Bignoniaceae WHUN Tecomaria capensis (Thunb.) Spach Dolichandrone cauda-felina Benth. & Hook. f. Bombax malabaricum DC. Ceiba speciosa (A. St.-Hil., A. Juss. & Cambess.) Ravenna Cordia dichotoma G. Forst. Ehretia thyrsiflora Nakai Isatis indigotica Fortune Buxus sinica (Rehder & E. H. Wilson) M. Cheng Viburnum odoratissimum Ker Gawl. Euonymus bungeanus Maxim. Perrottetia racemosa (Oliv.) Loes. Microtropis japonica Hallier f. Euonymus japonicus L. f. Cephalotaxus fortunei Hook. Cercidiphyllum japonicum Siebold & Zucc. Sarcandra hainanensis (C. Pei) Swamy & I. W. Bailey Hypericum ascyron L. Aspidistra elatior Blume Coriaria japonica A. Gray Benthamidia japonica (Siebold & Zucc.) H. Hara Carpinus tschonoskii Maxim. Juniperus chinensis L. Sequoia sempervirens (D. Don) Endl. Sabina pingii (W. C. Cheng ex Ferre) W. C. Cheng & W. T. Wang Chamaecyparis pisifera (Siebold & Zucc.) Endl. Sphaeropteris lepifera (Hook.) R. M. Tryon Carex oahuensis Hillebr. Daphniphyllum longeracemosum Rosenth. Dillenia turbinata Finet & Gagnep. Hopea chinensis (Merr.) Hand.-Mazz. Hopea hainanensis Merr. & Chun Cyrtomium yamamotoi Tagawa Diospyros kaki L. f. Elaeocarpus apiculatus Mast. Sloanea hemsleyana Rehder & E. H. Wilson Rhododendron kaempferi Planch. Pieris japonica D. Don ex G. Don Itea yunnanensis Franch. Bischofia polycarpa (H.Lév.) Airy Shaw Sapium biglandulosum Müll.Arg. Excoecaria acerifolia Didr. Excoecaria cochinchinensis Lour. Bridelia tomentosa Blume Cassia siamea Lam. Erythrophleum fordii Oliv. Crotalaria sessiliflora L. SCBG Bombacaceae SCBG WHUN Boraginaceae Brassicaceae SCBG SCAU SCBG Buxaceae WHUN Caprifoliaceae Celastraceae Cephalotaxaceae TUAT SCBG WHUN TUAT TSUK WHUN Cercidiphyllaceae TUAT Chloranthaceae WHUN Clusiaceae Convallariaceae Coriariaceae TSUK KUMN TSUK Cornaceae TUAT Corylaceae Cupressaceae TUAT TUAT TSUK KUMN TUAT Cyatheaceae SCBG Cyperaceae TSUK Daphniphyllaceae KUMN Dilleniaceae Dipterocarpaceae SCBG SCBG SCAU WHUN TUAT SCAU Dryopteridaceae Ebenaceae Elaeocarpaceae KUMN Ericaceae Escalloniaceae TUAT TSUK KUMN Euphorbiaceae SCBG Fabaceae SCBG WHUN WHUN SCAU SCBG SCBG TSUK Dry leaf content (10 ml agar-1) 10 mg 50 mg R% H% R% H% 62.8 112 38.0 120 Criteria 82.4 106 35.2 87.6 59.1 114 49.0 79.3 68.0 107 26.8 90.8 30.7 58.1 53.5 75.7 109 123 17.8 40.4 32.8 73.5 96.5 74.1 *** * * 55.2 81.0 31.6 75.4 * 78.1 45.9 65.1 83.8 95.2 87.9 99.2 84.2 129 115 117 138 65.5 47.5 39.1 74.6 51.2 68.6 124 129 99.4 116 96.8 124 67.3 109 47.0 102 76.5 142 35.6 108 94.7 62.9 79.7 92.2 90.0 104 47.1 42.6 46.3 87.6 79.4 90.7 91.3 99.0 44.9 110 81.3 88.7 90.0 118 102 114 78.0 75.1 57.0 121 105 119 100 121 91.4 117 116 127 94.9 135 103 126 76.0 117 57.6 60.2 57.9 75.3 79.4 91.4 68.4 93.8 60.2 59.4 119 94.3 108 94.6 113 56.8 136 133 119 117 26.7 26.3 60.1 59.8 69.5 23.5 69.9 54.9 107 90.8 89.9 43.9 96.9 98.3 48.3 41.5 61.6 114 86.2 85.9 148 124 31.0 105 64.1 65.3 154 110 34.8 80.6 12.2 31.1 *** 44.4 45.1 73.7 86.2 40.6 42.4 53.6 52.6 91.0 129 179 66.7 56.1 88.9 17.8 16.8 63.1 20.8 14.6 37.9 20.8 27.5 45.2 97.6 82.5 63.7 100 55.9 ** ** * ** * * * ** ** * International Journal of Basic and Applied Sciences Plant families POC Scientific Name Fabaceae SCBG WHUN TUAT SCBG SCBG SCBG SCBG TSUK TUAT TUAT TUAT TUAT TUAT TUAT SCAU TUAT TUAT TUAT KUMN SCBG TUAT TSUK TUAT TSUK SCBG TUAT SCBG TSUK SCBG TSUK KUMN TSUK SCBG TUAT Pongamia pinnata (L.) Pierre Wisteria sinensis (Sims) DC. Styphnolobium japonicum (L.) Schott Sindora tonkinensis A. Chev. Saraca dives Pierre Pithecellobium lucidum Benth. Bauhinia blakeana Dunn Macroptilium atropurpureum (L.) Urb. Quercus myrsinifolia Blume Quercus glauca Thunb. Lithocarpus glaber Nakai Quercus gilva Blume Lithocarpus edulis Nakai Quercus serrata Murray Lithocarpus glaber Nakai Quercus acutissima Carruth. Ginkgo biloba L. Ginkgo biloba L. (Fruit） Loropetalum chinense Oliv. Altingia chinensis Oliv. ex Hance Hamamelis japonica Siebold & Zucc. Hemerocallis fulva L. Aesculus turbinata Blume Hydrangea macrophylla (Thunb.) Ser. Iris japonica Thunb. Platycarya strobilacea Siebold & Zucc. Vitex quinata F. N. Williams Callicarpa japonica Thunb. Epimeredi indica (L.) Rothm. Scutellaria baicalensis Georgi Callicarpa macrophylla Vahl Keiskea japonica Miq. Akebia quinata (Thumb. ex Houtt.) Decne. Stauntonia hexaphylla Decne. Lindera fragrans Oliv. Machilus oculodracontis Chun Cinnamomum osmophloeum Keneh. Cinnamomum burmannii (Nees & T. Nees) Blume Laurus nobilis L. Cinnamomum porrectum (Roxb.) Kosterm. Cinnamomum camphora (L.) J. Presl Litsea verticillata Hance Tupistra glandistigma Wang et Tang Nephrolepis cordifolia (L.) K. Presl Lagerstroemia speciosa (L.) Pers. Lagerstroemia indica L. Magnolia liliiflora Desr. Manglietia lucida B. L. Chen & S. C. Yang Magnolia sirindhorniae Noot. & Chalermglin Manglietia insignis Blume Magnolia obovata Thunb. TUAT Magnolia grandiflora L. Fagaceae Ginkgoaceae Hamamelidaceae Hemerocallidaceae Hippocastanaceae Hydrangeaceae Iridaceae Juglandaceae Lamiaceae Lardizabalaceae Lauraceae TSUK TSUK WHUN SCBG WHUN SCAU TUAT SCBG Liliaceae Davalliaceae Lythraceae Magnoliaceae TUAT SCBG SCBG KUMN SCBG TUAT SCBG SCBG SCBG 387 Dry leaf content (10 ml agar-1) 10 mg 50 mg R% H% R% H% 55.4 98.2 32.3 100 56.5 82.7 67.0 87.9 59.7 115 26.5 84.6 73.2 114 54.8 115 60.6 111 49.5 107 64.6 135 47.5 143 65.1 74.8 33.5 85.0 99.5 107 34.2 100 75.4 106 93.6 122 80.6 109 45.2 95.9 81.1 108 62.3 131 82.4 90.1 68.5 81.1 84.9 105 61.4 114 86.3 104 54.8 107 111 153 74.3 132 95.1 124 64.0 121 80.8 108 25.6 79.2 83.5 106 30.1 69.4 61.6 98.7 31.1 66.7 73.7 105 57.1 119 76.9 115 57.4 103 35.5 69.9 36.2 73.2 71.0 96.3 61.7 109 65.9 80.1 55.9 100 52.5 89.2 23.5 63.7 67.6 117 38.9 86.8 60.2 88.3 23.1 65.5 60.4 76.7 48.0 92.8 69.2 119 44.4 81.0 72.2 108 41.9 97.7 87.4 113 62.6 99.1 107 159 41.8 123 65.7 104 55.2 86.4 94.7 62.2 69.2 76.0 120 95.3 107 110 66.1 41.7 30.3 42.7 147 87.3 68.9 62.6 88.6 108 45.9 91.2 68.7 118 42.3 77.1 73.2 96.5 70.7 112 82.2 74.3 65.7 88.3 81.7 85.8 35.4 108 107 92.1 122 125 117 64.9 54.7 52.0 35.3 65.1 17.5 36.7 26.3 121 96.5 72.5 120 63.9 91.0 56.9 64.8 82.0 35.9 95.6 69.7 100 23.8 45.1 71.3 73.1 123 105 37.6 44.0 97.1 73.4 84.7 100 81.3 121 Criteria * * * * *** * * * *** 388 International Journal of Basic and Applied Sciences Plant families POC Scientific Name Magnoliaceae TUAT SCAU Liriodendron tulipifera L. Michelia balansae Dandy Michelia sphaerantha C.Y. Wu ex Z.S. Yue Michelia fadouensis D. X. Li & Y. W. Law Magnolia Kobus DC. Michelia figo (Lour.) Spreng. Michelia yunnanensis Franch. ex Finet & Gagnep. Michelia alba DC. Manglietia fordiana Oliv. Tsoongiodendron odorum Chun Hibiscus syriacus L. Hibiscus mutabilis L. Aglaia odorata Lour. Morus bombycis Koidz. Ficus drupacea Thunb. Ficus fistulosa Reinw. ex Blume Ficus benjamina L. Ficus lacor Buch.-Ham. Ficus annulata Blume Ficus microcarpa L. f. Myrica rubra (Lour.) Siebold & Zucc. Ardisia crenata Roxb. Rapanea neriifolia (Siebold & Zucc.) Mez Eugenia javanica Lam. Osmanthus matsumuranus Hayata Ligustrum lucidum W. T. Aiton Ligustrum compactum (Wall. ex G. Don) Hook. f. & Thomson ex Brandis Osmanthus fragrans Lour. Fraxinus longicuspis Siebold & Zucc. Osmanthus fragrans Lour. Olea europaea L. Epipactis thunbergii A. Gray Averrhoa carambola L. Corydalis taliensis Franch. Pinus parviflora Siebold & Zucc. Pinus thunbergii Parl. Piper sarmentosum Roxb. Piper sarmentosum Roxb. Platanus orientalis L. Indocalamus tessellatus (Munro) Keng f. Miscanthus condensatus Hack. Nageia nagi Britton & P.Wilson Podocarpus fleuryi Hickel Lysimachia daphnoides Hillebr. Anemone vitifolia Buch.-Ham. ex DC. Caltha palustris L. Ziziphus jujuba Mill. Sageretia thea (Osbeck) M. C. Johnst. Photinia glabra (Thunb.) Maxim. Amygdalus persica L. Prunus buergeriana Miq. Cerasus jamasakura (Koidz.) H. Ohba SCAU SCAU TUAT KUMN KUMN Malvaceae Meliaceae Moraceae Myricaceae Myrsinaceae SCAU SCAU SCAU SCBG SCBG SCBG TUAT SCBG SCBG SCBG SCAU SCBG WHUN TSUK TSUK WHUN Myrtaceae Oleaceae SCBG SCBG TUAT KUMN Platanaceae SCBG TUAT TUAT WHUN TSUK SCBG KUMN TUAT TUAT WHUN SCBG TUAT Poaceae WHUN Orchidaceae Oxalidaceae Papaveraceae Pinaceae Piperaceae Podocarpaceae Primulaceae Ranunculaceae Rhamnaceae Rosaceae TSUK SCAU SCAU TSUK KUMN TSUK TSUK SCBG KUMN TSUK TUAT TUAT Dry leaf content (10 ml agar-1) 10 mg 50 mg R% H% R% H% 85.8 106 45.3 92.2 102 145 61.7 147 Criteria 88.0 104 61.2 94.7 104 172 76.5 121 105 59.3 164 96.6 61.9 31.1 113 64.6 80.1 88.8 60.3 73.0 78.2 102 123 14.6 61.6 92.4 49.1 49.5 59.0 72.4 86.2 92.4 72.8 84.5 60.1 80.7 160 149 75.4 146 118 106 96.5 91.9 128 127 184 117 116 84.7 75.4 50.3 84.7 5.6 24.2 51.2 15.3 23.2 32.4 31.0 27.9 49.5 40.4 67.0 35.6 78.4 130 147 32.8 75.9 96.5 70.8 87.9 96.5 66.4 86.0 160 111 110 62.7 84.6 166 43.1 104 83.3 52.0 80.2 112 104 103 45.5 27.8 47.3 106 89.7 103 83.3 97.8 72.9 83.5 84.6 86.1 88.7 86.6 61.1 67.0 55.9 73.2 82.5 39.9 64.6 90.2 149 90.9 103 93.3 78.9 115 70.0 104 81.5 94.8 105 116 65.4 81.5 89.6 82.4 67.7 22.8 26.3 46.2 39.6 14.5 49.5 71.9 121 125 128 71.3 71.0 73.5 37.6 88.4 57.5 65.8 95.6 127 56.2 91.3 34.0 89.7 * 57.9 102 115 74.3 54.1 60.5 59.5 80.8 0.0 17.1 51.2 57.2 82.2 143 117 101 80.9 111 94.4 124 0.0 29.1 112 89.0 46.2 77.6 55.2 16.3 38.9 37.4 23.1 48.4 0.0 13.1 17.2 57.3 88.2 89.5 68.4 47.4 59.1 104 59.1 104 0.0 26.8 81.8 88.1 * * ***** ** ** * * * * ** * * * ***** ***** * * International Journal of Basic and Applied Sciences Plant families POC Scientific Name Rosaceae TUAT Prunus yedoensis Matsum. Laurocerasus undulata (Buch.-Ham. ex D. Don) M. Roem. Prinsepia utilis Royle Eriobotrya japonica (Thunb.) Lindl. Prunus lannesiana E. H. Wilson Spiraea japonica L. f. Cerasus speciosa (Koidz.) H. Ohba Gardenia sootepensis Hutch. Psychotria rubra Poir. Acronychia pedunculata Miq. Atalantia buxifolia (Poir.) Oliv. Phellodendron amurense Rupr. Clausena lansium Skeels Citrus junos Siebold ex Tanaka Dimocarpus longan Lour. Sapindus mukorossi Gaertn. Litchi chinensis Sonn. Madhuca pasquieri H. J. Lam Astilbe microphylla Knoll Kadsura coccinea (Lem.) A. C. Sm. Anisodus acutangulus C. Y. Wu & C. Chen Datura metel L. Pterospermum heterophyllum Hance Styrax japonica Siebold & Zucc. Symplocos cochinchinensis (Lour.) S. Moore Taxus wallichiana Zucc. Taxus chinensis Roxb. Torreya nucifera Siebold & Zucc. Metasequoia glyptostroboides Hu & W. C. Cheng Metasequoia glyptostroboides Hu & W. C. Cheng Taxodium distichum (L.) Rich. Cryptomeria japonica D. Don Camellia oleifera C. Abel Camellia sasanqua Thunb. Ternstroemia gymnanthera (Wight & Am.) Bedd. Schima spp Camellia sasanqua Thunb. Daphne papyracea Wall. ex Steud. Tropaeolum majus L. Aphananthe aspera Planch. Zelkova serrata (Thunb.) Makino Celtis sinensis Pers. Boehmeria tenuifolia Satake Patrinia villosa Juss. Duranta erecta L. Hedychium coccineum Buch.-Ham. ex Sm. Alpinia oxyphylla Miq. Amomum tsaoko Crevost & Lemarie KUMN Sapotaceae Saxifragaceae Schisandraceae KUMN TUAT TUAT TSUK TUAT SCBG SCBG SCBG SCBG TSUK SCBG TUAT SCBG TUAT WHUN SCBG TSUK SCBG Solanaceae KUMN Sterculiaceae Styracaceae SCBG SCAU TUAT Symplocaceae SCBG Taxaceae KUMN WHUN TUAT Taxodiaceae TUAT Rubiaceae Rutaceae Sapindaceae TSUK Theaceae TUAT TUAT SCBG TSUK TUAT Ulmaceae Urticaceae Valerianaceae Verbenaceae SCAU TUAT KUMN TSUK TUAT TUAT TUAT TSUK TSUK KUMN Zingiberaceae WHUN Thymelaeaceae Tropaeolaceae Ulmaceae WHUN WHUN 389 Dry leaf content (10 ml agar-1) 10 mg 50 mg R% H% R% H% 77.1 113 56.4 109 Criteria 59.0 82.0 33.7 60.0 * 77.6 87.6 88.0 111 75.9 70.1 77.3 39.4 46.0 53.1 66.3 84.0 52.9 60.0 83.8 41.8 70.6 44.8 94.4 134 103 166 99.2 91.0 118 84.2 97.5 88.3 118 109 108 104 117 74.8 108 90.1 61.0 72.0 50.2 66.2 41.3 35.9 37.9 28.8 49.0 20.7 25.1 49.8 23.8 25.6 58.0 18.5 36.5 15.7 82.6 135 89.0 149 97.6 79.6 89.7 75.9 119 67.8 86.4 114 95.6 53.4 109 81.4 92.5 47.8 44.9 116 25.5 106 63.0 113 66.9 122 153 91.4 39.2 65.6 49.4 133 132 80.3 47.9 94.2 18.5 41.7 ** 35.1 56.2 98.5 98.2 128 128 36.0 35.4 73.9 54.8 102 104 *** * 53.7 116 14.8 92.4 * 56.7 78.6 29.4 66.0 * 82.9 107 50.4 71.0 117 121 80.7 75.6 33.0 88.9 14.1 26.5 78.5 117 45.8 32.3 75.6 107 69.6 115 77.2 83.6 41.5 60.0 65.2 71.8 88.3 70.2 86.9 43.3 166 110 111 116 119 138 112 113 118 77.6 35.5 56.1 24.8 31.2 38.4 35.4 45.6 30.4 57.0 7.7 119 78.0 66.1 73.2 97.2 129 113 108 112 26.2 66.0 100 31.1 80.0 54.3 67.9 109 149 24.7 21.8 70.9 90.4 *** ** * * * ** ** ** * ** * ** * * Criteria Indicates stronger inhibitory activity of test sample on the radicle elongation of lettuce by standard deviation variance (SDV) where: * = M– 0.5(SD), ** = M–1.0(SD), *** = M–1.5(SD), **** = M–2.0(SD), and ***** = M–2.5(SD). Thus SDV of 61, 50, 40, 29, and 19 respectively. Plant species with more * indicates increasing inhibitory activity. M: mean of radicle elongation, SD: standard deviation of radicle length, R: Radicle, H: Hypocotyl, %: elongation percentage of control. Values close to 0% indicate strong inhibitory activity in that plant species. POC; Place of collection. 390 International Journal of Basic and Applied Sciences Table 2: Determination of allelopathic activity by volatile compounds in some plant species in the Sino-Japanese Region using the dish pack method Plant families POC Scientific name Aceraceae Amaryllidaceae Annonaceae Altingiaceae Arecaceae Asparagaceae Asteraceae Berberidaceae Betulaceae Bombacaceae Caprifoliaceae Cephalotaxaceae TUAT TUAT TUAT TUAT TUAT WHBG SCAU TUAT SCAU TKBG TKBG TKBG TUAT SCBG TUAT WHBG Cercidiphyllaceae TUAT Cornaceae TUAT Cupressaceae TUAT Daphniphyllaceae KMBG Dipterocarpaceae Ebenaceae Elaeocarpaceae Fabaceae SCAU TUAT SCAU SCBG WHBG TUAT TUAT TUAT TUAT TUAT TUAT TUAT KMBG TUAT TUAT SCBG SCBG TUAT SCAU SCBG SCAU SCAU TUAT TUAT TUAT TKBG SCBG TUAT TUAT Acer cissifolium K. Koch Acer palmatum Thunb. Acer diabolicum Blume ex K. Koch Acer buergerianum Miq. Acer mono Maxim. Lycoris radiata Herb. Polyalthia longifolia (Soon.) Thwaites Liquidambar styraciflua L. Areca triandra Roxb. ex Buch.-Ham. Hosta sieboldiana (Hook.) Engl. Ligularia fischeri Turcz. Nandina domestica Thunb. Betula platyphylla Sukaczev Bombax malabaricum DC. Viburnum odoratissimum Ker Gawl. Cephalotaxus fortunei Hook. Cercidiphyllum japonicum Siebold & Zucc. Benthamidia japonica (Siebold & Zucc.) H. Hara Juniperus chinensis L. Daphniphyllum longeracemosum Rosenth. Hopea hainanensis Merr. & Chun Diospyros kaki L. f. Elaeocarpus apiculatus Mast. Saraca dives Pierre Wisteria sinensis (Sims) DC. Lithocarpus edulis Nakai Quercus serrata Murray Quercus gilva Blume Ginkgo biloba L. Hamamelis japonica Siebold & Zucc. Aesculus turbinata Blume Platycarya strobilacea Siebold & Zucc. Callicarpa macrophylla Vahl. Cinnamomum camphora (L.) J. Presl Laurus nobilis L. Tupistra glandistigma Wang et Tang Lagerstroemia speciosa (L.) Pers. Liriodendron tulipifera L. Michelia balansae Dandy Magnolia liliiflora Ders. Manglietia fordiana Oliv. Tsoongiodendron odorum Chun Magnolia grandiflora L. Magnolia megaphylla (Hu & W. C. Cheng) V. S. Kumar Magnolia kobus DC. Magnolia obovata Thunb. Morus alba L. Eugenia javanica Lam. Fraxinus longicuspis Siebold & Zucc. Ligustrum lucidum W. T. Aiton TUAT Pinus parviflora Siebold & Zucc. Fagaceae Ginkgoaceae Hamamelidaceae Hippocastanaceae Juglandaceae Lamiaceae Lauraceae Liliaceae Lythraceae Magnoliaceae SCAU Moraceae Myrtaceae Oleaceae Pinaceae Inhibition activity Average for Average at whole wells 41 mm R% H% R% H% 22.9 33.6 33.0 35.7 12.7 8.0 23.5 21.1 11.9 -0.8 13.1 -8.4 -2.8 -9.2 3.4 -14.6 -9.8 -6.6 14.3 -0.4 23.1 20.2 32.6 31.5 -7.6 0.5 -18.6 -6.6 61.4 2.8 61 3.1 21.4 21.7 30.8 29.9 21.7 11.3 24.5 13.3 10.3 8.9 11.0 10.1 22.1 13.1 26.2 25.4 -2.3 -10.9 -1.8 -12.4 -3.3 -15.3 -3.9 -25.7 2.1 -2.7 3.5 -1.7 -10.3 -12.9 -1.9 -1.1 27.0 9.1 31.8 6.7 13.9 -24.6 6.7 -37.7 24.5 18.5 34.0 15.1 3.5 -6.8 8.2 2.6 3.9 -11.0 20.0 2.4 0.4 22.7 4.5 -16.1 12.9 11.3 -33.0 34.9 1.3 50.2 3.6 1.8 3.6 19.1 12.8 10.7 10.1 7.2 4.8 1.5 -10.9 21.1 4.2 -1.1 1.9 -5.3 -6.4 -9.2 7.8 -7.9 17.9 1.6 59.9 5.0 1.6 0.9 7.8 -40.5 1.6 0.0 0.8 -2.2 8.1 -15.7 23.2 5.4 4.5 27.0 8.9 -11.3 13.2 4.0 -23.1 45.0 5.1 43.7 7.0 4.1 5.2 16.1 21.6 21.1 19.1 9.2 2.0 2.2 -17 21.1 5.6 0.3 13.9 5.5 -5.7 -12.9 3.2 -7.0 9.7 1.9 63.0 6.6 3.0 1.6 13.6 -32.9 7.9 -1.3 -0.7 -12.3 1.4 2.6 4.1 0.0 -3.1 -8.2 27.1 12.0 -10.0 10.9 2.1 -6.8 17.0 9.0 -4.1 6.7 2.8 0.3 29.7 23.6 -4.9 12.5 8.7 -1.1 19.3 18.0 2.3 7.9 35.5 29.9 35.7 29.8 Criteria + + *** ++ + ++ +++ * *** + + * International Journal of Basic and Applied Sciences Plant families POC Scientific name Platanaceae Podocarpaceae Rosaceae Schisandraceae Styracaceae TUAT SCAU TUAT TKBG KMBG TUAT TUAT TUAT TUAT SCBG TUAT WHBG SCBG TUAT Taxodiaceae TUAT Ulmaceae Zingiberaceae TUAT TUAT WHBG Platanus orientalis L. Podocarpus fleuryi Hickel Cerasus speciosa (Koidz.) H. Ohba Amygdalus persica L. Photinia glabra (Thunb.) Maxim. Prunus yedoensis Matsum. Prunus jamasakura Siebold ex Koidz. Prunus lannesiana E. H. Wilson Prunus buergeriana Miq. Gardenia sootepensis Hutch. Sapindus mukorossi Gaertn. Litchi chinensis Sonn. Kadsura coccinea (Lem.) A. C. Sm. Styrax japonica Siebold & Zucc. Metasequoia glyptostroboides Hu & W. C. Cheng Sciadopitys verticillata Siebold & Zucc. Zelkova serrata (Thunb.) Makino Alpinia oxyphylla Miq. Rubiaceae Sapindaceae 391 Inhibition activity Average for Average at whole wells 41 mm R% H% R% H% 1.8 -4.1 -1.1 -2.5 4.9 8.5 10.4 15.3 4.6 -10.3 18.2 -11.2 36.2 28.9 41.0 44.1 90.6 86.1 95.2 90.2 13.1 -1.4 24.0 -3.3 11.8 9.1 13.0 14.9 4.3 -4.3 7.3 7.6 -10.8 -2.6 -2.4 7.2 32.0 24.3 41.4 31.2 17.9 7.1 22.1 12.9 12.0 0.5 21.1 7.9 17.1 3.7 26.7 8.7 13.9 12.2 27.7 17.3 Criteria * *** + * 42.0 22.5 47.3 20.5 ** 38.4 12.9 29.0 37.3 2.3 26.4 42.0 14.4 34.5 49.3 12.4 39.6 * * Criteria (*), (**), and (***) refer to radicle elongation shorter than the mean value plus 1.0(SD), 1.5(SD) and 2(SD), that is, SDV = 31, 40, and 50, respectively. + Criteria (+), (++), and (+++) refer to radicle elongation longer than the mean value minus 1.0(SD), 1.5(SD) and 2(SD), that is, SDV = -6, -10, and -25, respectively. POC; Place of Collection. TUAT; Tokyo University of Agriculture and Technology, TKBG; Tsukuba Botanical Gardens, TMBG; Tokyo Medicinal Botanical Garden, WHBG Wuhan Botanical Garden, KMBG; Kunming Botanical Garden, SCBG; South China Botanical Garden, SCUA; South China University of Agriculture. Another species of interest in this family is Amygdalus persica which is a fruit of ornamental importance. A. persica is native to China where it have been cultivated for centuries [28]. Dried seeds of A. persica have been used in combination with other herbal plants to overcome stroke-induced disability [29], [30]. A. persica have been reported as a non-food biodiesel plant resources based on grey relation analysis with extremely complicated genetic diversity [31]. Glucosid amygdalin and hydrocyanic acid are the principal constituents of A. persica [32]. In the Malvaceae family, species that showed strong inhibition on lettuce radicle elongation was Hibiscus syriacus. Hibiscus syriacus is native to tropical climates, but are grown around the world for medicinal use and aesthetic value. H. syriacus have been used to treat ailments like gastrointestinal disorders, fevers, respiratory disorder as cough, used as emollient [33]. Sporopollenin observed from pollen of H. syriacus have a simple aliphatic polymer containing aromatic or conjugated side chains as the main structure [34]. In a screening for lipid peroxidation inhibitors, Yoo et al., [35] isolated three naphthalene compounds: 2,7-dihydroxy-6-methyl-8-methoxy-1-naphthalenecarboxaldehyde, 2-hydroxy-6-hydroxymethyl-7,8dimethoxy-1-naphthalene-carboxaldehyde, and 1-carboxy-2,8-dihydroxy-6- methyl-7-methoxynaphthalenecarbolactone, designed as syriacusins A–C, from the chloroform extract of the root bark of H. syriacus. All the three compounds inhibited lipid peroxidation. Novel cyclic peptide Hibispeptin a (C39H50N608) and Hibispeptin B (C36H52N6O8) have been isolated from the root bark of H. syriacus [36], [37]. In the Boraginaceous family, Cordia dichotoma had the highest inhibition on lettuce radicle elongation. Cordia dichotoma have been listed as non-consensus invasive woody plant in the coastal and dry lowlands in Mauritius [38]. This species have been used traditionally in India to treat ulcerative colitis (UC) and colic pain. Ganjare et al., [39] showed that apigenin isolated from the bark of Cordia dichotoma was responsible for the treatment of UC since it showed significant healing and reduction in inflammation enzymes when screened against UC. Polysaccharide in fruit of Cordia dichotoma is a potential candidate for use as herbal excipient in the formulation of orodispersible tablets [40]. The leaves and bark of Cordia dichotoma have shown high antioxidant, antimicrobial and ant implantation activities [41], [42], and [43]. The leaves have been found to contain querecetin and quecitrin whereas arabinoglucan, Larabinose and D-glucose have been found in the fruits [44]. Another species that showed strong inhibitory potential through the volatiles released is Liquidambar styraciflua (also known as sweetgum) of the family Altingiaceae. The major components of the leaf oil were reported to be styrene, dlimonene, α-pinene and β-pinene, and that of the stem oil were germacrine D, α-cadinol, d-limonene, α-pinene, and βpinene [45], [46]. These essential oils showed anti-inflammatory activity with low cytotoxicity thus backing its traditional use in treating inflammation. The emission of isoprene from sweetgum has been shown to be dependent on light and severe drought conditions [47], [48]. Some influenza viruses and the virus responsible for H1N1 are susceptible to the antiviral Tamiflu®. Shikimic acid is a precursor of oseltamivir phosphate which is the key ingredient 392 International Journal of Basic and Applied Sciences in Tamiflu®. However, much of the shikimic acid manufactured are generated by an Escherichia coli that produces shikimic acid [49], [50], [51]. Liquidambar styraciflua were found to contain shikimic acid in the bark and seeds [52], [53] and can potentially produce commercial quantities. 25-Acetoxy-3α-en-28-oic acid and 3β, 25-epoxy-3αhydroxylup-20(29)-en-28-oic acid isolated from the cones of Liquidambar styraciflua showed moderate anti-tumor promoter [54]. In the Amaryllidaceae family, leachates from L. radiata and L. aurea all highly inhibited the lettuce radicle elongation. The Amaryllidaceae family are mostly cultivated as ornamental plants and some are used as folk medicines for the treatment of some ailments [55]. The genus Lycoris comprises about 20 species that are wildly distributed in eastern Asia wood-lands, China and Japan in particular [56]. The allelochemical in L. radiata has been identified as lycorine [57]. However, allelopathy of L. aurea have not been reported. The bulb of L. aurea have been used in China to heal fractured bones [58]. Lycosinine A & B have been isolated from the bark of this species [59]. New alkaloids such as 2αhydroxy-6-O-n-buty-loduline, O-n-butyllycorenine and (-)-N-(Chloromethyl) lycoramine have been isolated from the bulb of L. aurea. All the compounds exhibited significant neuro-protective effects against CoCl2 and H2O2-induced ShSY5Y cell death [55]. Pi et al., [60] reported that some alkaloids isolated from bulb of L. aurea showed significant cytotoxicity against all tumor cell line (seven) tested. The alkaloids 3-0-ethyltazettinol 2α-methoxy-6-O-ethyloduline have also been isolated from the bulb of L. aurea [61], [62]. 5. Conclusion The results from this study hereby provide brief insight on the allelopathic potentials of some plants in the SinoJapanese Floristic Region. Further research can be conducted on the identification and characterization of allelochemicals using this data as benchmark information. Information as such could aid in the development of bioactive compounds from plant species into natural herbicides and also the utilization of these plants in sustainable weed control. We will present in our subsequent report the allelochemical(s) responsible for the inhibitory activity in Photinia glabra which was the strongest allelopathic species in this study. Acknowledgements This research was supported by the grant-in-aid for research work on Agriculture and Food Science (25029AB) from the Ministry of Agriculture, Forestry and Fisheries of Japan. This work was also supported by JSPS KAKENHI Grant Number 26304024. 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