evaluation of forage yield and important agronomic indices of corn affected by intercropping systems with peanut and nitrogen rates

introduction multiple cropping such as intercropping plays an important role in agriculture because of maximizing beneficial interactions. intercropping of legumes and cereals is an old practice in tropical agriculture that dates back to ancient civilization. maize-legume intercrops could substantially increase forage quantity and quality and decrease requirement for protein supplements (ahmad et al., 2008). intercropping of cereals and legumes is important for development of sustainable food production systems. this may be due to some of the potential benefits in intercropping systems such as high productivity and profitability, improvement of soil fertility through the additional supply of n by fixation and excretion from the component legume, efficient use of resources, reducing damage caused by pests, diseases and weeds and improvement of forage quality (ahmad et al., 2008; fernandez-aparicio et al., 2007; lithourgidis et al., 2006). the main advantage of intercropping is more efficient utilization of the available resources and the increased productivity compared with each sole crop of the mixture. therefore, this experiment was conducted to evaluate agronomic characteristics of corn and land equivalent ratio (ler) under intercropping with peanut and different rates of nitrogen. materials and methods in order to evaluate the forage yield and important agronomic indices of corn (zea mays l.) affected by intercropping systems with peanut and different nitrogen rates, this experiment was performed in the experimental field of agricultural and natural resource research center of guilan province, rasht, iran, during 2013-14 cropping season as a split plot arrangement in randomized complete block design with three replications. nitrogen rates, including of zero, 100, 200 and 300 kg per hectare as main plot and sole cropping of corn and peanut (arachis hypogaea l.), intercropping systems including of intercropping corn and peanut at ratio of 1:1, 2:1, 1:2 and 2:2 on alternative furrows as sub plot, comprised the experimental factors. results and discussion the results of this experiment showed that the effects of nitrogen were significant for all measured characteristics except the leaf number, leaf length and wide. also, the effects of intercropping were significant for all study traits except the ear diameter, leaf number, leaf length and wide. in addition, the interaction effects of the nitrogen × intercropping system were significant for peanut seed yield, corn forage yield, stem weight, stem diameter, ear diameter, leaf length and land equivalent ratio. the results of this experiment showed that the application of 300 kg nitrogen per hectare obtained the highest corn forage yield under (c6) intercropping system. at the same condition, no significant difference was observed for corn forage yield between (c4) and (c6) intercropping systems. the interaction between 100 kg n/ha × c5 intercropping system at the ratio of 1:2 showed the greatest peanut seed yield. peanut seed yield decreased by increasing the nitrogen application rate. however, based on this experiment results, application of 300 kg nitrogen per hectare increased total production of both corn and peanut and land equivalent ratio (ler= 1.51) under (c3) intercropping system. the land equivalent ratio (ler) under 100 and 300 kg per hectare and intercropping system of corn with peanut (c4) by the ratio of 2:1 was 1.42 and 1.39, respectively. there was no significant difference between the land equivalent ratio (ler) under above mentioned conditions. the results showed that maize-peanut intercropping increased corn forage yield compared to peanut seed yield. hence, increment of land equivalent ratio (ler) related to corn forage yield more than seed yield of peanut. conclusion in general, results showed that maize-peanut intercropping could be profitable due to use of the available resources. maize-peanut intercropping system can decrease yield loss caused by pest and disease and enhance soil fertility. maize-peanut intercropping pattern can increase productivity compared to sole cropping. according to our results, intercropping system of corn with peanut (c4) by the ratio of 2:1 and utilizing of 100 kg nitrogen per hectare could be recommendable for enhancement of crop production and increment of farmers economical income in rasht and similar climatic conditions. acknowledgement the authors gratefully acknowledge the comments and suggestions received from agricultural and natural resources research and education center of guilan province.