EFFECTS OF DIFFERENT CONCENTRATIONS OF GIBBERELLIC ACID (GA₃) ON THE GERMINATION OF ‘CLEOPATRA’ MANDARIN SEEDS (Citrus reshni Hort. ex Tanaka)

Abstract

The ‘Cleopatra’ mandarin (Citrus reshni Hort. ex Tanaka) is an economically important rootstock widely used in citrus production for its productivity, vigor, and ability to induce earlier fruit ripening. Its complex taxonomy and preservation by nucellar embryony underscore the need for specific studies on its propagation. Research indicates that growth regulators such as gibberellic acid (GA₃) can enhance germination, although gaps remain regarding the physiological responses. Therefore, this study evaluated different GA₃ concentrations (0, 1000, 2000, 3000 and 4000 mg L⁻¹) on the germination of ‘Cleopatra’ mandarin seeds under controlled BOD germination-chamber conditions. Germination percentage (%G), index of germination velocity (GSI) and mean germination time (MGT) were measured, and the data were analyzed by normality tests, ANOVA and polynomial regressions. Results showed a significant treatment effect on GSI, with 1000 mg L⁻¹ producing the highest germination velocity, while the shortest MGT was estimated near 2600 mg L⁻¹ by polynomial fitting; final germination percentage exhibited a complex nonlinear response with no clear differences among all treatments, suggesting the need for greater sample size to confirm these trends. It is concluded that GA₃ improves aspects of the germination process of Citrus reshni Hort. ex Tanaka at low to intermediate doses—particularly 1000 mg L⁻¹ for germination velocity—and that the findings support optimization of seed-imbibition protocols and further investigation of physiological mechanisms and population variability.