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The effect of plant density and detopping on grain yield and its componets of single cross 704 maize hybrid was investigated at Kushkak Agricultural Research Farm of Shiraz University located at Doroodzan area of Fars province, in 1996. The experiment was arranged as split plots in a randomized complete blotk design with four replicates. The treatments
composed of: detopping of plants two weeks after pollination at four levels i.e. leaving one, two, three leaves above the ear and control (intact plants) as main factor, and density at four levels i. e. 5.55, 6.66, 8.33 and 11.11 plants m-2
as sub-factor. The results showed that the highest grain yield (11250 Kg ha-l)
was produced when the plants at 11.11 plants m-2 density were detopped, with leaving tow leaves above the ear. The number of kernel rows per ear was not affected by detopping, however, the highest row number per ear
(15.4)observed in the lowest population density treatment(i.e.5.55 plants m-2). Maximum kernel number per ear row was achieved when three leaves were.
left above the ear at the lowest population density. The lowest density in the absence of detopping also produced the heaviest grains(293. 8 g for 1000 seeds). The highest population density in the absence of detopping had the highest leaf area index. The amount of forage resulted from detopping was
highest at the highest plant density with maximum detopping i.e. when only one leaf left above the ear. Harvest index of the plants at 6.66 plant m-2
density with leaving only 0['& leaf above the ear was the highest (52.3%). This experiment revealed that it might be possible to detop the maize plaMts and get some forage and even increase the grain yield of maize crop.