This study was conducted at the vegetable field of department of
horticulture and landscape design, college of agriculture and forestry ,Mosul
university, during spring of 2007 and 2008, to study the effect of times and
levels of nitrogen fertiliz
ation on some characters vegetative growth, flowering
,and yield of summer squash .Result indicated that, the time of nitrogen
fertilization at the stage of fruit-set caused a significant increased in the leaf
number /plant ,length of the plant and the fresh weight/plant. While the time of
nitrogen fertilization wasn't affected significantly the total yield. The level at
320 kg.N/ha caused a significant increase of the characters vegetative growth
and total yield. Also result revealed that, the interaction between the stage at
fruit set and nitrogen fertilization at 320 kg.N/ha led to increase the total yield
.The yield was found to positively correlation with the plant length ,fresh and
dry weights of plant, leaf area, fruit weight, male and female flowers, and the
sex ratio.