Effect of plant growth regulators on the tuberisation and physiological age of potato (Solanum tuberosum L.) tubers grown from true potato seed

Abstract

The effects of plant growth regulators [6-benzyl amino purine (BA), indole-3-acetic acid (IAA), 2,4-dichlorophenoxyacetic acid (2,4-D), gibberellic acid (GA3), chlormequat chloride (CCC), daminozide] and their time of application on tuberisation and physiological age of cv. Chacasina F1 grown from true potato seed (TPS) were studied in four experiments conducted in spring or autumn in Greece. BA, IAA and 2,4-D did not affect plant development, tuberisation or the physiological age of the tubers produced. Daminozide and CCC reduced plant height when applied 30 but not 60 d after transplanting (DAT) in both spring and autumn. Neither substance affected tuberisation or the physiological age of the tubers formed. Application of GA3 30 DAT significantly increased plant height and the number, but not the weight, of tubers formed per plant. Tubers from GA3-treated plants tended to be elongated with a low dry matter content. When GA3 was applied at 60 DAT, plant height was increased, but tuber number, weight and dry matter content were not affected. Late application of GA3 induced a high percentage of sprouted tubers prior to harvest and significantly increased the physiological age of the tubers, as reflected by an increased rate of respiration, sprouting and weight loss after harvest. Although early application of GA3 also increased tuber sprouting prior to harvest, it had no effect on sprouting, respiration and weight loss after harvest. Application of GA3 early in the vegetative cycle may be useful for the production of mini-tubers for propagation, whereas application at a later stage may aid in early planting by accelerating the breaking of tuber dormancy. Key words: Gibberellin, chlormequat chloride, daminozide, dormancy, tuberisation