The Production, Storage, and Translocation of Carbohydrates in Developing Potato Plants

¹⁴C-tracer experiments showed that the export of assimilateslabelled with a short pulse of ¹⁴CO₂ continued for 5 weeks.There appeared to be an approximately exponential loss of ethanol-insoluble¹⁴C from the haulm with a half-time of about 3.5 weeks. Initiallythere was a poor correlation between the fresh weight of thetubers and their ¹⁴C content but the correlation became goodafter 5 weeks. Field data showed that, in many instances, the rate of tubergrowth was greater than the rate of growth of the whole plant.This suggests the transfer of large amounts of dry matter fromthe haulm to the tubers. Dry-matter loss from the haulm couldaccount for the discrepancy and the amount transferred in thisway was about 10 per cent of the final dry weight of the tuber. There was an increase in net assimilation rate when the leafarea of the plants started to decline. It is suggested thatthis increase was due to an increase in the rate of photosynthesisbrought about by the influence of the rapidly growing tubers.