Abstract
This experiment was conducted in an unheated plastic house in Horticulture and Landscape design Department, college of Agriculture and Forestry, Mosul University during the winter season of the year 2013-2014 to investigate the possibility of lettuce crop production under protected condition during the winter season, which cannot be grown in the field at this time in Mosul City. Two lettuce cultivars were used Binco and Paris Island, the seeds were planted in 5/9 and transplanted inside the unheated plastic house in 5/11 at two agricultural distances: 30 and 40 cm and plants were fertilized with two organic fertilizers: Pow hums and Humistar which were applied to the soil as a solution at a rate of 3 gm.l-1 for the two organic fertilizers, the control treatment was fertilized with a chemical fertilizer at the recommended rates. An RCBD factorial experiment with 12 treatments (2 x 2 x 3) were used. Results showed that there were no significant differences between the two varieties in most vegetative growth and yield traits while there were a significant superiority of the 40 cm distance on the 30 cm distance in head circumference, leaf area, stem weight and mean marketable head weight while there were a significant superiority of the treatment of 30 cm planting distance in terms of marketable and total yield. It is worth to note that there were no significant differences between the organic fertilization treatments with the normal chemical fertilized plants in terms of vegetative and yield in all vegetative traits mentioned traits expect the mean stem weight.
