Three dual-purpose hybrids were evaluated in Nazlo region (Urmia University, Agricultural College) during 2001-2002.The hybrids were planted in nine different planting densities of 60,70,75,83,87,90,104,105 and 125 thousand plants/ ha. The experiment was a Factorial-split with base design of Randomized Complete Block with 4 replications. For every hybrid and every plant density fresh weight of different
components of plant i.e stem and sheath, leaf, tassel, ear and dry weight of grain and cob, grain yield and biological yield were determined, and also Harvest Index (HI), leaf: stem, grain: cob, and ear: other components ratios were calculated. Variance analysis of data showed significant statistical difference between hybrids in all traits with the
exception of ear and cob weight. In means comparison using Dunkan method, hybrids as compared with each other showed significant difference in all traits. Under the experimental conditions of this experiment, it appears that planting density of 83000 plants ha-1 is optimal for production of best forage quality in hybrid KSC647, while
planting densities of 70000-87000 and 104000 plant ha-1 are optimal for hybrids KSC704 and KSC301, respectively. Also, simple correlation coefficients of traits were evaluated. Grain and biological yield exhibited significant correlation (0.619). Besides, the highest correlation was observed between grain yield and grain: cob ratio (0.795).
)