بررسي جنبه هاي اكوفيزيولوژيك و تعيين دوره بحراني كنترل تاج خروس ريشه قرمز (Amaranthus retroflexus L) در ذرت دانه اي

Study of echophysiologic of aspects and critical period control Amaranthus retroflexus L. in corn field

In order to determination of critical period control of pigweed in corn, an experiment was conducted in a RCBD in three replicates in Tabriz Islamic Azad University, Agricultural research station. Weed interference period was in 6 levels (2, 4, 6, 8, 10 weeks after corn emergence, and all of growth period) and weed free period was also in 6 levels (2, 4, 6, 8, 10 weeks after corn emergence, and all of growth period). Results showed that weed interference levels had significant effect on plant height, kernel number in cob, and kernel yield. The highest lose in kernel yield was belonged to weed contamination in all of growth period. This proved the importance of weed control in suitable situation. Leaf area index differences between weed contamination in all of growth period and weed free period in all of growth period was significant. Simultaneous growth of corn and pigweed in first 6 weeks after corn establishment had not significant effect on yield. Fitted curves for determination critical control period showed that there was a critical control period for 5% and 10% yield decrease in 3 to 44 days and 5 to 38 days after com emergence, respectively.