The potato dry matter change in response to weeds interference

To study the competitive effects of redroot pigweed (Amaranthus retroflexus) andlambsquarter (Chenopodium album) on potato, an additive experiment was conducted in thespring of 2004 and 2005 in split-split plot based on randomized complete block design with4 replications at the Seed Potato Production Station of RAN in Firouzkooh. Treatmentsincluded 2 weed species in main plots (Amaranthus retroflexus and Chenopodium album),weed density in sub plots (2, 4 and 8 plants per meter of row) and relative time of weedemergence in sub-sub plots (8 and 4 days prior to potato and the same time with potatoemergence in 2004 and the same time with potato, 2 and 4 weeks after potato in 2005).Results showed that both weed species reduced biological yield. TDM reduction in 2005were 27.5 and 25.1 percent less than 2004. Redroot pigweed caused 33.8 and 38.1% more potato dry matter reduction than lambsquarter.