اكوفيزيولوژي رقابت ذرت و دوعلف هرز تاج خروس و سلمه در شرايط كم نهاده و پرنهاده

Ecophysiology of corn (Zen mays L) competition with redroot pigweed (Amaranth= retroflexus l.) and common lambsquqrters (Chenopodium album L) in low and high input conditions

In order to study the effects of different levels of water and nitrogen on yield and yield components of corn in competition with weeds, an experiment was conducted in springs 2002 and 2003 • in farm research of Pests and Plant Diseases Institute in Karaj with 3 factors in a split factorial design with four replications. The factors were: irrigation cycle (2 levels) as main plot and nitrogen fertilizer (2 levels) and mixture planting of corn, red root pigweed and common lambsquirters plantings (8 levels) in a factorial arrangement as subplotes. The combined analysis of results showed that in sole corn plots, yield and yield components of corn were the highest and after that the treatments corn and common lambsquarters, corn and redroot pigweed,and corn and redroot pigweed and common lambsquarters were placed. The interaction of competition treatments and nitrogen levels, and competition and watering cycle showed that the highest decrease in yield and yield components of corn was due to corn + redroot pigweed and corn + redroot pigweed + common • lambsquarters treatments. The ranked water use efficiency was redroot pigweed> corner common lambsquarters and in 7-day watering cycle was more than 14-day one. In water and nitrogen deficiency, optimal quantum yield of PS II decreased. It seems that corn can tolerate water stress more than nitrogen stress.