Effects of photoperiod and growth substances on tuberization of potato (Solanum tuberosum L.)

Abstract

Four growth chamber and greenhouse experiments were conducted to determine the effects of photoperiod on tuberization of rooted stem cuttings of Solanum tuberosum L. cv. Russet Burbank, Norchip, and Red McClure. The results showed that tuberization can be controlled by growing the plants under the appropriate photoperiod. Rooted stem cuttings grown under long photoperiods (16 and 18 hours) produce few or no tubers. Short photoperiods (8 and 12 hours) increased the rate of tuberization in all experiments. Maximum tuberization occurred at the 12 hour photoperiod. Long photoperiods also stimulated vegetative top growth, particularly stem elongation while under the short photoperiod stems were relatively short. The fresh weight of tubers per plant decreased as the length of the photoperiod increased. A marked tendency for plants to branch was observed with plants under long photoperiod. Under the 8 hour photoperiod, plants developed a single stem, but as the length of the photoperiod increased, the plants showed a greater tendency to branch. Maximum branching occurred under a 16 hour photoperiod. Rooted Norchip stem cuttings did not appear to respond to the treatment photoperiods when compared to the Russet Burbank and Red McClure cuttings. Norchip is apparently a day neutral potato cultivar. Exposure of Russet Burbank and Red McClure "Mother plants" to inducive (10 hr) and non-inducive (16 hr) photoperiods had a marked effect on the tuberizing ability of apical stem cuttings taken from these plants. Apical stem cuttings from the 10 hour photoperiod treatment tuberized earlier and produced heavier tubers whereas cuttings from the 16 hour photoperiod produced few or no tubers in all experiments. Rooted stem cuttings of Solanum tuberosum L. cv' s. Russet Burbank, Norchip, Red McClure and Centennial Russet were treated with 2,4-dichloranisole (DCA), 2,3,5-tri-fodooenzoic acid (TIBA), Indol-3-Acetic acid (IAA), Naphthalene acetic acid (NAA) and Ethrel (E) at various concentration. No significant trends were observed with any of the growth substances with respect to their potential for increasing the number and fresh weight of tubers per plant.