Abstract: The study on the photosynthetic characteristics of Phalaris arundinacea, the dominant plant in Beigu Mountain wetland, showed that on sunny days in spring and summer, the net photosynthetic rate (P_n) of P. arundinacea had a diurnal change with two peaks, exhibiting an obviously phenomena of midday depression, while on cloudy days, the P_n was mainly affected by light intensity.The P_n was positively correlated with photosynthetically available radiation (PAR) and stomatal conductance (G_s), while negatively correlated with intercellular CO₂ concentration (C_i). The light-response curve of P. arundinacea could be quantitatively simulated by quadratic equation, with the obtained light compensation point being 38.572 μmol·m^-2·s^-1 and light saturation point being 2 087.5 μmol·m^-2·s^-1.

Key words: Oryza sativa, Allelopathy, Agronomic character, Weed-inhibiting effect, Variety