Effect of different levels of N fertilizer on yield and yield components of maize (Zea mays L.) under different densities of annual ground cherry (Physalis divaricata L.) competition

To study the competition effects of annual ground cherry (Physalis divaricata) on maize yield under different rates of N fertilizer, a field experiment was conducted in 2017 in Kermanshah Agricultural and Natural Resources Research and Education Center, Kermanshah, Iran. The experimental design was a randomized complete block with factorial arrangement with three replications. Treatments included nitrogen fertilizer (50%, 100% and 150% recommended rates) and annual ground cherry density (0, 8 and 16 plants/m2). Results showed that the highest and lowest grain yield were 9929 and 6143 kg h-1 respectively that were belonged to weed free with 150% recommended N and 16 plant annual ground cherry/m2 with 50% recommended N, respectively. High densities of annual ground cherry reduced grain yield, grains per row, row number per ear and 1000 kernel weight. Different N rates caused significant variations in grain yield and some of the yield components of maize and annual ground cherry properties like dry weight and height. Overall, results indicated that in fields, where annual ground cherry is the dominant, increasing N application rate to 150% recommended rate, increased maze yield by 17.02