This work aimed to study the genetics of green cotyledon of Todo-verde cultivar using two groups of crossing. The first one the Todo-verde cultivar was crossed with Bettergreen and Green Dixie Blackeye cultivars to test allelic relationship between Todo-verde cultivar gene and the gc gene present in these cultivars. The second one the Todo-verde cultivar was crossed with BRS-Guariba and BR2-Bragança cultivars to study the inheritance of the green cotyledon. All the crosses were performed in greenhouse and the experiment was carried out in the field, under irrigation by a conventional aspersion system at Embrapa Meio-Norte, in Teresina, Piaui, in 2004. We used a completely randomized design with four blocks. The parental constituted the common treatments and the generations F1, F2 and the backcrossing the regular treatments. Qui Square test was used to analyze the data. The allelism test indicated that the gene that produces the green cotyledon presented by Todo-verde cultivar is not allelic with gc gene which produce the same trait in Bettergreen and Green Dixie Blackeye cultivars. The inheritance study showed that Todo-verde cultivar green cotyledon is controlled by a single recessive gene. The name green cotyledon-2 and the symbol gc-2 were suggested to the new gene.
