Cold-induced sweetening in tuber ends of potato (Solanum tuberosum L.) genotypes

Abstract

It is a known fact that cold-induced sweetening (CIS) is produced more in tuber ends that rest of tuber parts
in potatoes. But most of the studies so far have been directed to whole tuber while tuber end studies are reported very rare.
In the present study, CIS is measured in tuber ends of potato genotypes, “Lady Rosetta†and “Kufri FryoM†(processing),
“Kufri Sindhuri†and “MS/8 1148†(non-processing) during storage at 4° (cold) and 25°C (control) in four-way interaction
experiment. Tubers were harvested after 30 d of haulm cutting and hardened in field for 10 d and then stored. Tubers
were analysed at 0, 20, 40, 60 and 90 d after storage. Results found that amylases increased, and starch decreased at 4°C
in non-processing genotypes only and changes were more marked in basal than apical ends. Starch decreased at earlier
stages (20 and 40 d), but amylases increased throughout the storage, at 4°C. Soluble sugars increased at 4°C where glucose/
sucrose increased relatively earlier (at 20-40 d) than fructose (at 20-60 d). Increase of glucose and fructose at 4°, was higher
in non-processing than processing genotypes and in basal than apical ends. However, increase of sucrose at 4°, was higher
in “Lady Rosetta†and “MS/8 1148â€. Principal component analysis (PCA) related fructose, more closely than glucose, to
amylolysis. Results indicated that sucrose synthetic/breakdown activities may be involved in CIS, and sucrose synthetic
activity may relate to CIS-resistance of “Lady Rosettaâ€.