The investigation on “Allelopathic effects of Terminalia arjuna (Roxb.) Wight & Arn. on Oryza sativa L. var. GNR-2” was carried out in the year 2015-16 at Department of Natural Resource Management, ASPEE College of Horticulture and Forestry, Navsari Agricultural University, Navsari (Gujarat) in bioassay culture and pot culture. The experiment comprised of Terminalia arjuna tree and Oryza sativa L. variety GNR-2 at four concentrations of leaf leachate and bark leachates viz.5 % concentration of leaf and bark leachate, 10 % concentration of leaf and bark leachate, 15 % concentration of leaf and bark leachate and 20% concentration of leaf as well as bark leachate which were assessed by completely randomized design experimental design. A B S T R A C T In bioassay culture, significantly maximum germination percentage was recorded under control of T9 (90%). The germinative energy was significantly maximum in leaf leachateT2 (5.74). The mean daily germination was maximum in bark leachate of T8 (43.89). The peak value was maximum (9.83) under 5 percent bark leachat as well as control. The mean germination time was significantly maximum under 15 percent bark leachate (48.61). The shoot length was maximum under 15 percent bark leachate (7.99 cm). Similarly, root length was maximum under 15 percent bark leachate (12.75 cm). The fresh weight was maximum under 20 percent bark leachate of T8 (1.69 g). However, dry weight was significantly maximum under 20 percent leaf leachate T4 (0.97 g). Name of Student Major Advisor Patel Jitendrakumar Nathubhai Dr. Dileswar Nayak But incase of pot culture significantly maximum plant height was recorded under bark leachate of T5 (84.25cm). The number of tillers per plant was maximum under bark leachate T5 (13.25). The root length was maximum under bark T5 The Gas Chromatography-Mass Spectrometery (GC-MS) analysis of the bark leachate and leaf leachate samples showed that the chemical compounds present in the T. arjuna have allelopathic as well as other phytochemical properties. The bioassay and pot culture studied divulged that, the bark and leaves of T. arjuna contain different types of phytotoxic chemicals, as evident from GC-MS analysis, with putative inhibitive as well as stimulatory potential on growth and biomass of Oryza sativa. However, pot culture studies, intended to examine the effect of leaf leachate and bark leachate, underpinned that, different leachate treatment inhibitive effect on final growth, of Oryza sativa against T. arjuna. (34.14 cm). The soil parameter under significantly maximum pH was recorded under leaf leachate T8 and control (7.87). The electrical conductivity was significantly maximum under bark leachate of T8 (1.56 dsm-1). The organic carbon was significantly maximum under T8 (0.77 %). The available nitrogen content was maximum under control T9 (221.09 kg/ha) followed by 20 percent leaf leachate (232.85 kg/ha). The available phosphorus content was maximum under leaf leachate T1 (19.54 kg/ha) and available potassium was maximum under bark leachate T5 (338.33 kg/ha).