Abstract
Early developmental stage of rice (Oryza sativa L. cv. Koshihikari) seedlings was found to release a growth inhibitor, momilactone B into the neighboring environment from their roots. In the present study, the release level of momilactone B from rice seedlings during their interior life cycle was monitored. Release level of momilactone B was increased with the their growth. At day 15 after transferred to hydroponics, the level of momilactone B in the culture solution was 1.8 nmol per seedling compared with the endogenous level of 0.32 and 0.63 nmol per root and shoot, respectively, which suggests that rice seedlings may release momilactoneB into the culture solution actively. Release level of momilactoneB and its effectiveness as a growth inhibitor suggest that it may act as an allelochemical by inhibiting growth of neighboring plants, indicating that momilactoneB might play an important role in rice defense system against weed.
