The Effect of Pretreating Seedlings with Bap on Direct Shoot Regeneration from Petiole Explants of Sugar Beet (Beta VulgarisL.)

A 100% seed sterility and 75.6% seed germination rate were achieved when seeds of three sugar beet (Beta vulgaris L.) breeding lines were surface sterilized with a combination of 0.5% Domestos and 5% PPM™. As an in planta treatment with BAP, the sterilized seeds were germinated on MS basal medium containing 1, 3 or 5 mg/l BAP for five weeks and then petiole explants were excised from the seedlings and cultured on two different regeneration media; RGL medium containing 0.5 mg/l BAP and 0.1 mg/l NAA, and RGH medium containing 1.0 mg/l BAP and 0.5 mg/l NAA. Petiole explants taken from seedlings pretreated with 1 mg/l BAP produced significantly more shoots (0.97 shoot per explant) than those taken from seedlings pretreated with 3 or 5 mg/l BAP (0.68 and 0.59 shoot per explant, respectively). The RGL medium containing lower BAP and NAA was significantly more effective in direct shoot production than the RGH medium containing higher BAP and NAA, 1 shoot per explant compared to 0.48, respectively. 21.1% of the regenerated shoots developed roots on medium containing 3 mg/l NAA whereas only 4.1% of the shoots rooted on medium containing 1 mg/l NAA. Genotypic variation was significantly evident for both shoot regeneration and rooting.