b"The Double Life of SugarsExplaining why sugars can be good, but also bad for potatoes.BY: ASHLEY ROBINSONPOTATO SUGAR LEVELS can be good ortemperature sweetening bad depending on what stage of the life theor cold-induced sweetening, potato is in. Paul Bethke, a plant physiologistpick your favourite term. Chips with the United States Department ofor fries stored warm might have a Agriculture, dove into the double-edged lifenice colour, but as you store them in of potato sugars during a presentation at thean increasingly cooler temperature, you virtual Washington-Oregon Potato Conferenceincrease the rate of sucrose production. on Jan. 26, 2021. Heres an overview of his mainThis is because sucrose production is a points about the double life of sugars. common response to low temperature stress in potatoes and in other plants, and chips What are sugars? or fries become darker and darker. Sucrose Sugars are produced by leaves from sunlight,increases as the temperature drops, and an carbon dioxide and water, in the process ofincrease in invertase is triggered by cooler photosynthesis, one of the most amazingtemperatures as well. processes in all of biology. Those sugarsAnother plague of the processing industry is are used for growth of the plant and forreducing sugars that accumulate during sugar maintenance of existing structures. end defect formation. The difference between beautiful french fries and these sad french Why are sugars needed for potatoes? fries is the sugar ends, the accumulation Once we have potatoes forming, the potatoesof sucrose that occurred on the stem grow off of sugars. Sucrose made in leaves isend of these potatoes as a result of an transported down the stem, through the stolonenvironmental stress, that also increased and ends up in developing tubers. That sucrosethe activity of invertase. And when they were is the foundation for starch production. It'scooked, you got these dark ends.worth noting that where the sugars go in a plant depends on the time of year.What is the duality of sugars?Early in the season, sucrose and otherSugars are essential for tuber sugars produced by leaves are used to producebulking, but they can be additional leaves and stems. That is, theproblematic for processing vine dry matter content increases. Later inquality. Sunlight is one of the season, almost all of the new dry matteryour most valuable inputs, accumulation occurs in tubers. This is relevanttry to maximize your use to us because it tells us is that in the first half ofof it. And finally, when the growing season, we produce the vines, wewe're thinking about produce the leaves. And then we have to usechip and fry quality, those vines and those leaves during the secondhigh quality depends half of that season to fill the tubers, at a timeon managing sucrose when we're not making any more leaves. Weand avoiding invertase, just have to maintain them and protect them. which largely means avoiding stresses that When do sugars cause problems? cause the potatoes to Cold storage increases tuber sucrose andproduce elevated sucrose and invertase both, and as a result, we see low- elevated invertase. SPUDSMART.COM Fall 202133"