INDUCTION AND GENERATION OF FLOWERING IN CABBAGE PLANTS BY SEED VERNALISATION, GIBBERELLIC ACID TREATMENT AND RATOONING

Abstract

Experiments were conducted to determine whether applying seed vernalisation or gibberellic acid treatment, alone or in combination, can induce flowering in cabbage plants raised from seeds and ratoons at relatively high temperatures (20° – 25°C), and to determine whether new flowering plants can be generated from flower-induced plants. Seeds of ten varieties of cabbage were imbibed in 302.44 g l–1 polyethylene glycol 6000 and exposed to vernalisation temperatures (2.0° – 4.5°C) for 8 weeks in a refrigerator, while controls were kept at 25°C for 11 d, after which the seeds were sown and plants raised at 20° – 25°C. Ratoon plants were also raised from control and seed-vernalised plants from the previous experiment. Forty five d after transplanting, or 28 d after removing the heads, 250 mg l–1 gibberellic acid (GA3) was applied to the leaves of plants raised from seed or ratoons respectively, followed by six further applications at 1-week intervals. The combined effects of seed vernalisation and GA3 induced flowering in cabbage plants of variety ‘HRT 009617’ developed from seeds or ratoons. None of the treatments had any adverse effect on the percentage germination of subsequent seeds produced from those varieties that flowered. All showed 89%, or higher germination. Cuttings from the reproductive stalks of flowering-induced plants were able to flower at 20°C, without vernalisation.