Seeds Collected from Different Ziziphus joazeiro Plants Are Differently Affected by Gibberellic Acid

Ziziphus joazeiro is a tree endemic to Caatinga, Northeastern Brazil, with great economic potential. However, its commercial production is still limited due to low and non-uniform germination of seeds. Recently we demonstrated that gibberellic acid (GA₃) stimulates the emergence and uniformity of seedlings in this species. In its natural habitat, however, great morphological diversity between Z. joazeiro trees is found, suggesting great genetic variability. Therefore, it was necessary to test if the GA₃ effect is a general response. We collected seeds from four plants maintained in a collection. The plants were selected according to contrasting morphological characteristics. After breaking impermeability with 98% sulfuric acid, the seeds were treated with 2 mmol L^?1 GA₃ or a control with distillated water for 24 h. Effects ranged from great, low, and no effect of GA₃ stimulating the percentage and rapidity of emergence between genotypes tested. For reforestation, thus, the GA₃ treatment of Z. joazeiro seeds might reduce its genetic variability; but for economic production, it will be an adequate and simple treatment to increase the quantity and uniformity of seedlings.