The study was conducted at the vegetable field, College of Agriculture and Forestry, University of Mosul, Iraq, during the spring season of 2007 and 2008 to investigate the responses of five summer squash cultivars namely local cultivar, Asma, Nadi, Tala and Zucchini to three concentrations of Licorice (0.0 ,1.5, 3.0) gl-1 so the experiment involved 15 treatments arranged in a Factorial Randomized Complete Block Design with three replicates.The result could be summarized that foliar spraying with Licorice extract at 3.0gl-1 gave significant increase in seeds weight fruit-1 and the total yield of seed in both seasons, whereas, number of fruits held for seeds extraction were increased significantly during the season of 2007 only. Local and Tala cultivars were significantly superior over the weight of seeds fruit-1 during 2007, but in 2008 season Tala cv. was distinguished giving the highest value in seeds weight fruit-1 accounted 76.54 g which varied significantly with Asma cv. only. On the other hand, the Local cv. was characterized upon the studied cultivars in the seeds yield during 2007 season, whereas, during 2008 the superiority cultivars over (Local, Zucchini, and Tala) which gave (130.02 , 130.71 and 146.69) g plant-1 respectively .
The best interaction treatment in seeds yield plant-1 was (3.0 g l-1 Licorice in local cv.) which had a significant difference as compared with other treatments recorded (94.31) g in 2007 season ,while in 2008 it was noticed that Tala cv. + 3.0 g l-1 licorice produced the highest seeds yield 155.57 gplant-1.The total seeds yield was significantly correlated with, weight of 1000 seeds and seed length in both two seasons .The traits seed length and weight of 1000 seeds exhibited direct effect on the total seeds yield, and had indirect effect on the seeds yield through the other traits.