Four field experiments were carried out at Mallawi (Middle Egypt) and i
Shandawill (Upper Egypt). Research Stations. Agricultural Research Center during "
2001 and 2002 seasons. To study are the effect of plant population and nitrogen
fertilizer levels and their interaction on yield and yield components of maize. Split plot design was used with four replications. The main plots were randomly
assigned to the four plant population I.e. 15. 20. 24 and 30 thousand plants/fed
obtained from planting at 40. 30. 25 and 20 cm with one planUhill. The subplots
devoted to nitrogen fertilizer rates of 30. 60. 90, 120 and 150 Kg Nffed. the most
important results could be summarized as follows:         1-    The increases in maize plant density from 15.000 to 30.000 plants/fed significantly
increased means of plant height, ear height and the period from planting to 50 %
tasseling or silking but the yield components were decreased by increasing
densities. Grain yield 0 f maize was significantly affected by plant density. Plant
population 30,000 plants/fed had the highest grain yield followed by 24,000
plants/fed.        2-    Raising nitrogen levels from 30 to 150 Kg N/fed increased growth, yield and yield
components characters and reduced the period from sowing to 50 % tasseling or
silking, 3- No significant differences between grain yield/fed of 120 and 150 Kg Nlfed and
between 24 and 30 thousand planUfed. it can be recommend that to produce
higher and economical grain yield/fed must fertilizer with 120 Kg N/fed and
plant density is 24000 planUfed. 4- The treatment of plant density of 24,000 planUfed with 120 Kg N/fed gave the
highest yield, there for it could be recommended to maximize maize productivity
under the environmental conditions of the present study.