Monitoring Nutrient Levels during the in Vitro Tuberization of Potato

Macro- and micronutrient levels were monitored during the in vitro tuberization of potato (cv. Alpha) in liquid medium of MS salts and vitamins supplemented with 8% sucrose and 5 mg·liter–1 kinetin under complete darkness at 18C. Microtubers were formed in 50% of the cultured jars at day 20 and reached their full size at day 60 of culture initiation. By this time, medium N, P, and K levels had dropped by 89%, 84%, and 41%, respectively. The major drop in medium N occurred during the pre-tuberization stage, when it was taken up mostly by shoots. During tuber enlargement, the rate of Zn, Fe, and Mn removal from medium was slower than their rate of uptake by tubers. The changes in shoot and tuber Ca were very small where most of the Ca removed from medium was diverted into the roots.