Photoperiod, gibberellic acid, and kinetin, in potato flower differentiationin vitro

Abstract

To inducein vitro floral differentiation on potato plantlets, one cm long apical explants cv. Marijke were excised and aseptically cultured in a semi-solid medium containing Murashige-Skoog salts supplemented with 0.3 mg/l indoleacetic acid; with or without one mg/l gibberellic acid (GA); 0.3, 3.0 or 30.0 mg/l Kinetin (K); 20, 40 or 60 g/l sucrose (S) and 8% agar, pH 5.7. After a five week growing period at 26–28 C with daily light PAR 35 μE/m2/sec, 14 or 24 h daylength (DL), flower buds developed with exposed sepals and an abscission zone in the peduncle. Statistical significance was found when the variation factors (GA, K, S, and DL) were analyzed individually or in combination for number and weight of floral buds. Absence of GA favored the number of buds/plant, and the interaction of continuous light with a culture medium containing 0.3 or 3.0 mg/l kinetin and 40 g/l sucrose induced the highestin vitro “yields” in number and weight of flower buds (6 per plant and up to 14 mg/bud), followed by premature abscission. In a similar experiment, to prevent such abscission, plants from five week old tissue culture were transferred to soil and maintained at 24 h DL and 26–28 C, but flower bud abortion could not be avoided. These results demonstrate the importance of manipulating exogenous factors (growth regulators, sucrose, photoperiod) to inducein vitro specific organogenesis in potatoes.