a study of variation in weed population and yield of peanut (arachis hypogaea l.) under two different planting patterns and some different plant densities in guilan province

an experiment was conducted in bandar kyashahr research field in 2002 to evaluate the effects of plant density and planting pattern on weed populations and yield of peanut (arachis hypogaea l.). the experiment was of a randomized complete block design with three replications. a factorial trial with two factors of planting pattern (square and rectangular arrangements) and plant density (3, 5.3, 8.3 and 14.8 plants per m2) was employed. the results showed that planting pattern and plant density affect pod yield and that square planting pattern and 8.3 plant/m2 yielded more pod than the rectangular planting pattern and the other plant densities. during the first weeding period, planting pattern and plant density had no effect on weed dry weight and the number of weeds. in contrast, in the second weeding period, planting pattern and plant density had a cosiderable and significant effect on weed dry weight and the number of weeds. during the third and the fourth weeding periods, although planting pattern had no effect on weed dry weight and the number of weeds, plant density did have. the second and the third weeding periods of planting patern exhibited a significant effect on the number of pegs and branches. moreover, these numbers in square planting pattern being higher than that in the rectangular arangement. the most important weeds of the experiment included: amaranthus retofelexus l., solanum nigrum l., chenopodium album l., and protolaca oleracea l. the 14.8 and 8.3 plants/m2 and square pattern of arrangement were finally decided as more effective in weed control than the other treatments.