Abstract: In order to investigate the effect of weedy rice stress on grain yield of cultivated rice and its physiological mechanism,weedy rice JS-Y1 and rice cultivar Nanjing 44 were chosen as test materials in field experiment to study the effects of different densities(0,4,8,12,16 plant/m²) of weedy rice stress on photosynthetic characteristics,chlorophyll fluorescence parameters,transmittance,lipids peroxidation and defensive enzyme activities and yield components of cultivated rice.The results showed that with the increase of weedy rice density,weedy rice suppressed the physiological stress indicators of cultivated rice in varying degrees at different growth stages comparing with the control,the transmittance in the height above the soil surface 20,50,80 cm and height below panicles 10 cm were declined by 54.03%-72.49%,39.68%-61.57%,48.98%-54.40% and 38.07%-56.76%,had significant difference compared with their controls,SPAD,photosynthetic parameters,Ф_PSⅡ,qP,lipids peroxidation and defensive enzyme activities were declined with the different growth stages and the increase of weedy rice density,especially in the middle of filling stages.The production of cultivated rice with densities of 4,8,12,16 plant/m² weedy rice decreased by 16.73%,43.01%,66.61%,83.24%,had significant difference compared to control (no weedy rice planted).It was indicated that the main reasons causing the yield loss of cultivated rice was weedy rice with different densities stress on transmittance of cultivated rice population,caused the cell membrane system decomposed and the declined photosynthetic capacity.

Key words: Weedy rice, Cultivated rice, Photosynthesis, Physiological characteristics

CLC Number: 

• S511.01