An experiment was carried out in the fields of Agriculture College-Baghdad University during spring and autumn of 2015 by using a randomized complete blocks design with three replications. The first season hybridization was established among three pure cultivars of cowpea (Vigna uniguiculata L.) which: Ramshorn, California black eye and Rahawya in full diallel crosses according to Griffing with first method and fixed model (3 parents+ 3 diallel hybrids +3 reciprocal hybrids) and a comparison experiment was in autumn season. The result of statistical analysis showed that there was a significant difference among the parents and their hybrids for all the studied characters. The parent 1 was the higher for root nodules number , leaf number, pod number average pod weight , and pod yield per plant .The diallel cross 1*2 was the higher to pod number 33.27 pod/plant and 2x3 to average pod weight 8.10 g pod-1 and the reciprocal cross 2*1 was higher for green pod yield 285.40 g plant-1. The values of average degree of dominance was 0.873 cm/plant for plant height in diallel crosses while it was more than one for plant height and pod weight average in reciprocal crosses. The heritability in broad sense was high to all characters while in narrow sense it was high to plant height in diallel crosses 68.78% while it's values were high to moderate for most the traits in reciprocal crosses.
In order to serve the field of knowledge in the field of design and analysis of experiments by adopting formulas and methods that are easy and simple in arithmetic work, especially in experiments that require many calculations for squares, including tests of type