EFFECT OF SPRING AND AUTUMN SEASON SOWING DATES ON YIELD OF CORN SYNTHETIC VARIETIES. ( Zea mays L.)

The experiment was carried out at the field of the college of Agriculture and Forestry, Mosul univ. During spring and autumn seasons of 2010, to study the effect of sowing dates for two seasons on grain yield and its components and quality characters of four corn varieties (Zea may L.) . Randomized complete block design with three replications was used , each replicate included sixteen treatments combinations , four sowing date(in spring 1st and 15th march , 1stand 15th April), and( in autumn season 1st ,10th ,20th and 30th July),with four synthetic varieties Danya, Buhouth -106 , Sara and Rabee. The showed that most of characters were affected by planting date in both seasons. Corn plants which sowing at third date for both seasons and first date in autumn were surpass for yield and some yield components which were reflected on yield production as compared with the fourth date in both seasons. The varieties showed significant differences on their response to growth characters, yield its components and seed quality. the variety buhouth-106 had higher value for most growth characters and oil percentage at both seasons as compaired with other varieties. The variety Danya had higher value for most yield characters. Yield components and quality characters in both seasons. The interaction between sowing date and varieties showed highly significant differences in all growth ,yield and quality characters in both seasons. In spring the variety Danya which was sown in the third date had height grain yield ,but on autumn season the variety Rabee which was sown at third date had higher grain yield.