Abstract: To investigate the feasibility of using exogenous salicylic acid (SA) to regulate the allelopathic weed suppression of rice, this paper studied the effects of different concentrations exogenous SA on the weed-suppression and physiological-biochemical characteristics of allelopathic rice PI312777, and the relative expression quantity of gene ZB8 in the rice by real time quantitative RT-PCR (FQ-PCR). The results showed that exogenous SA induced the enhancement of the allelopathic potential of donor rice in suppressing target weed plants, and this inducing effect was SA dose and treatment time dependent. After foliar spraying SA, the inhibitory effect of PI312777 on barnyardgrass increased significantly, and the root vigor and superoxide dismutase (SOD) and perocidase (POD) activities of PI312777 increased, while its catalase (CAT) activity decreased. The reverse was true for the target weed barnyardgrass. At the same time, the phenylalanine ammonia-lyase (PAL) activity of PI312777 increased significantly, leading to an increase of the total content of phenols. Among the test concentrations of SA, 0.2 mmol·L^-1 had the best inducing effect, under which, the relative expression quantity of ZB8 increased first and decreased then, with a peak at 24 hours after treatment.

Key words: dissolved organic matter, freeze-thaw disturbance, soil leachate, three-dimensional fluorescence spectroscopy-parallel factor analysis., soil moisture