The phenomenon of allelopathy, w h e re plant species chemically interfe res with seed germination, and growth or development of other plant species has been known for over 2000 years. The term of allelopathy, is a word, to describe all kinds of re c i p rocal biochemical interactions (inhibitory as well as stimulatory) among plants. Pinus eldrica Medw. is one of the most common t rees planted in Iranian parks and urban landscapes. According to the wide use of these t rees in urban landscap e, experiments we re conducted to study the allelopathic effect of P. e l d ri c a M e d w. l e aves on four turfgrass seed germination and seedling growth using the sandwich and extraction methods.In the sandwich method, 5 mL agar (5%) was added to 6 petridishes containing 5 g (in dry weight) of P. eldrica Medw. fresh leaves.After solidification, 3.2 mL agar (5%) was added to the leaves agar layer. Twenty seeds of each turfgrass genus (Lolium perenne L., Festuca arundinacea Schreb., Poa Pratensis L. and Agrostis capillaris L.) was placed on the agar culture medium separately, with five replications per genus u s e d . After 7 day s , the seed germination percentage and the length of shoot and root of seeds were measured. In the extraction method, a completely randomized design (CRD) was used with 5 replicates of each turfgrass genus at four concentrations of leaf extracts (25%,50%,75% and 100%) along with control. Hundred seeds of each turfgrass in 5 replicates were placed on the filter papers inside the petri-dishes and were irrigated with deferent concentration of P. eldrica Medw. leaf extracts. The seed germination percentage and rate, and root length of seedlings in each Petri-dish were measured after10 days.To prevent increasing.....

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