Effect of Plant Density on Some Agronomical Traits of Corn in Intercropping With Cowpea

In order to evaluate the effect of plant density on some agronomical traits of corn with cowpea intercropping (substitution method), an experiment was conducted in 2010 in the Agricultural Research Station of Khoy as split plot on the basis of randomized complete block design with three replications. The main plots were planting density in levels of 55, 70, 85 thousand plants for corn and 150 000, 200 000, 250 000 plants for cowpea per hectar and sub plots were included five planting ratio of corn – cowpea, as R1= pure corn planting, R2= 75% corn + 25% cowpea, R3= 50% corn + 50% cowpea, R4= 25% corn + 75% cowpea and R5= pure cowpea planting. Results showed that the effects of plant density were significant on 100- corn kernel weight, grain and biological yield of corn. The planting ratio of corn and cowpea significantlyaffected all measured traits of corn except the ear number, grain yield and harvest index. Also the harvest index of corn was significantly affected by interaction of plant density and planting ratio of corn - cowpea. The highest grain (1034 g/m2) and biological yield (2293 g/m2) of corn was observed at the highest densities (85000 plants/ha). Biological yield of corn in intercropping treatments was more than sole cropping, So that the highest amount of biological yield, Land Equivalent Ratio (2/17) and Relative Value Total (1/86) was obtained in density of 85000 plants/ha and 50% corn + 50% cowpea intercropping. Based on results combination of 85 thousand plants per ha in 50% corn + 50% cowpea intercropping was more suitable than those other treatment combinations