Md Sirajul Islam Khan
Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, 2393, Ikenobe, Miki, Kagawa 761-0795, Japan
A. K. M. Mominul Islam
Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, 2393, Ikenobe, Miki, Kagawa 761-0795, Japan
Hisashi Kato-Noguchi
Allelopathic activity, Mango, Fruit, Mango cultivars
Bangladesh Agricultural Research Institute, Gazipur, Bangladesh
Socio-economic and Policy
Mature leaves of three mango (Mangifera indica L.) cultivars (Khirshapat, Himsagor and Sinduri) were collected from Bangladesh Agricultural Research Institute, Gazipur-1701, Bangladesh. Leaves were washed with tap water, sun dried and kept under refrigeration at 4°C until extraction. Seeds of six test species, viz., cress (Lepidium sativum L.), lettuce (Lactuca sativa L.), alfalfa (Medicago sativa L.), Italian ryegrass (Lolium multiflorum Lam.), barnyard grass (Echinochloa crus-galli (L.) Beauv.) and timothy (Phleum pratense L.) with uniform shape and size were selected for the current research. Among these, first three are dicotyledonous and the rest of them are monocotyledonous. The seeds of cress and lettuce were obtained from Nakahara Seed Product Co. Ltd. (Fukuoka, Japan) and Tohoku Seed Co. Ltd. (Utsunomiya, Japan), respectively. The seeds of alfalfa, Italian rye grass and timothy were obtained from Takii Co. Ltd. (Kyoto, Japan) and barnyard grass seeds were from the farmer’s fields (Kagawa, Japan). Leaves of mango (50 g dry weight) were cut into small pieces and extracted with 400 mL of 80% (v/v) aqueous methanol for 48 h. The extract was filtered through one layer of filter paper (No. 2; Toyo Ltd., Japan), using a vacuum pump. The residue was re-extracted with equal volume of methanol for 24 h and filtered. The two filtrates were combined and evaporated to dryness using a rotary evaporator at 40°C. All the activities (washing, drying, storing, extraction) were done separately for each mango cultivars during the whole research work. Required volume of the extract was dissolved in methanol to get four different extract concentrations of 0.003, 0.01, 0.03 and 0.1 g dry weight (DW) equivalent extract mL-1. The extract was then added to a sheet of filter paper (No. 2) in 2.8 cm Petri dishes. The methanol was evaporated in a draft chamber and then the filter paper was moistened with 0.6 mL of 0.05% (v/v) aqueous solution of Tween 20 (polyoxyethylene sorbitan monolaurate; Nacalai, Kyoto, Japan): a surfactant that is non-toxic to seeds. A Petri dish without leaf extract served as control containing only Tween 20 on filter paper. The bioassay was carried out with three replications and repeated twice. Before starting the germination bioassay, seeds of timothy, Italian ryegrass and barnyard grass were soaked in distilled water for 24 h to imbibe the seeds. Ten seeds of cress, lettuce, alfalfa, Italian rye grass, barnyard grass or timothy were placed on filter paper in Petri dishes, covered with aluminum foil and kept in a germination chamber at 25°C in dark. Germination was measured by counting the number of germinated seeds at every 12 h of interval up to 96 h according to the procedure stated by Islam and Kato-Noguchi (2013a). Growth bioassay: The extract preparation and placing in Petri dishes were done according to the same procedure as described in previous section. Then 10 seeds of cress, lettuce or alfalfa, or 10 germinated seeds of Italian ryegrass, barnyard grass or timothy (germinated in the darkness at 25°C for 24-72 h) were arranged on the filter paper. All of the Petri dishes were kept in a growth chamber for 48 h at 25°C in dark. The shoot and root lengths of the emerged seedlings were measured and inhibition percentage was determined using the equation as prescribed by Islam and Kato-Noguchi (2012). Each experiment was carried out using a Completely Randomized Design (CRD) with three replications and the experiments were repeated twice. All the data were analyzed by MSTAT-C (Russell, 1984) and are subjected to three-way ANOVA. The concentration at which the growth of test plants was reduced by 50% (I50) was performed on the basis of curve fitting to a logistic equation, using Graph Pad Prism 6 (Graph Pad, Inc., San Diego, CA, USA)
Asian Journal of Plant Sciences, 12 (6-8): 252-261, 2013; ISSN 1682-3974
Journal