Effect of sowing date and nitrogen level on yield and yield components of two extra early maize varieties (Zea mays L.) In Sudan Savanna of Nigeria

A two year field study was conducted during 2000 and 2001 rainy seasons at Kadawa (11 0 39’N,08 0 2’E and 500metre above sea level) in Sudan savanna of Nigeria to study the effect of Sowing dates and nitrogen level on yield and yield components of two extra early maize varieties. The end of June sown maize had the highest cob length, cob diameter and cob weight compare with other dates throughout the period of study except in 2000 where mid-July sowing produced longer and heavier cobs. Application of nitrogen up to 80 kg N ha -1 increased the cob length, cob diameter and cob weight in all the two years. Further increase of nitrogen to 120 kg N ha -1 did not result in increase in diameter. The optimum grain yields were obtained from the maize sown at the end of June in all the years and mid-July sown maize in 2000. Nitrogen application significantly increase grain yield up to 80 kg N ha -1 while further application did not affect the grain yield.