Induction of Flowering in Texas Early Grano Onion Cultivar Using Vernalization and Gibberellic Acid under Gezira State Conditions, Sudan

Abstract

Field experiments were conducted at the research farm of the Faculty of Agricultural Sciences, University of Gezira, Wad Medani, Sudan, during seasons of 2008 to 2010. Treatments consisted of vernalization periods, which ranged from 30 to 180 days, vernalization temperatures of zero to 14° C and gibberellin concentrations ranging from zero to 600 ppm. Results indicated that vernalization temperatures of 4 to 5° C for 90 days or more was the key factor for the induction of flowering in Texas Early Grano cultivar. Application of GA3 alone, without vernalization, at all concentrations tested failed to induce flowering. However, the highest bolting percentage and seed yield were obtained by a combination of vernalization at 4 to 5° C for 180 days and the application of GA3 at the rate of 600 ppm. It is recommended to vernalize bulbs of “Texas Early Grano” cultivar at 4 to 5° C for 180 days with the application of GA3 at the rate of 600 ppm for seed production under Gezira conditions.