Different concentrations of gibberellic acid on the germination rate of four varieties of corn (GA3) (Zea mays L)

Abstract

This study was conducted to evaluate the effect of different concentrations of Gibberellic acid (GA₃) on seed germination and early seedling growth of four maize cultivars (Zea mays L.), namely: local (Libyan), Egyptian, Indian, and American maize, under controlled laboratory conditions. The experiment was arranged in a factorial design including two factors: cultivar and Gibberellic acid concentration. Four concentrations were used: control (0 ppm) and three GA₃ concentrations (25, 50, and 100 ppm), with three replicates for each treatment. Seeds of each cultivar were soaked in Gibberellic acid solutions for a period ranging from 8 to 24 hours, while control seeds were soaked in distilled water only, then thoroughly rinsed with distilled water. Seeds were placed in Petri dishes lined with moistened filter paper at a rate of ten seeds per dish and incubated at a constant temperature of approximately 25°C for seven days. Germination was recorded daily. The measured parameters included the number of germinated seeds, germination percentage, shoot length, and root length on the seventh day. Statistical analysis using two-way analysis of variance (ANOVA) revealed significant differences among cultivars in germination percentage (p < 0.05), while the effects of Gibberellic acid concentrations and the interaction between cultivar and concentration were not statistically significant overall. The local cultivar recorded the highest germination percentage, followed by the Indian and American cultivars, whereas the Egyptian cultivar showed the lowest values. The results also indicated that low and moderate GA₃ concentrations (25–50 ppm) were more effective in enhancing germination and early seedling growth compared to the high concentration (100 ppm), which caused a reduction in germination in some cases. These findings suggest that the response of maize seeds to Gibberellic acid is largely dependent on the cultivar and the applied concentration