Enhancement of Tuberization of Axillary Shoot Buds of Potato (Solarium tuberosum L.) Cultivars Cultured In Vitro

Factors controlling growth and tuberization of axillary buds in shoots of plantlets of potato (Solarium tuberosum L.) cultured in vitro were investigated. Correlative inhibition restrained growth and tuberization of the axillary buds. Exposure of intact plantlets for various periods (4 to 48 h) to low (2 or 12 °C) or high (30 °C) temperatures as compared to 18 °C, did not alleviate correlative inhibition. Removal of the apical part of the shoot, the roots or both was generally ineffective. Elevating sucrose concentration from 30 to 80 g dm-3 promoted tuberization on axillary buds, and the cytokinin 6-(yy-dimethylallylamino) purine (2iP), alleviated correlative inhibition and enhanced tuberization in intact plantlets. In the whole plantlet most of the tubers were formed on the basal nodes, however, once correlative inhibition was eliminated by the dissection of the shoot to single node sections, tubers were formed on every axillary bud. The single most effective factor inducing tuberization in single node sections was the growth retardant ancymidol, an inhibitor of giberellin biosynthesis.