Screening potato (Solanum spp) for cold-induced sweetening

Abstract

During storage at low temperature reducing sugars in potatoes (Solanum species) increase rapidly, as a result tubers become sweet and are not preferred for table as well as processing purposes. For developing potato varieties suitable for cold chipping, 16 wild and two semi-cultivated species were screened for reducing sugars content at harvest and after three months storage at 4°C. Tubers of 105 clones of 47 accessions of the 18 species harvested from summer crops (for two years) raised in glasshouse at Shimla were used for these evaluations. Significant differences were observed between as well as within species, accessions and clones of an accession for reducing sugars content both before and after storage. At harvest, the reducing sugars content ranged between 4.52 mg/100 g fresh weight in S. berthaulti (‘SS 1785- 06’) to 1 122.97 mg/100 g fresh weight in S. cardiophyllum (‘SS 1825-12’). After storage, it ranged between 80.56 and 3229.49 mg/100 g fresh weight in clones ‘SS 1920-01’ and ‘SS 1920’ respectively of S. microdontum. Clones with low reducing sugars at harvest were not necessarily having low reducing sugars after cold storage also, indicating that per cent increase in reducing sugars content varied with the genotype. Six promising clones with reducing sugars <100 mg/ 100 g fresh weight at harvest and <200 mg/100 g fresh weight after storage were: ‘SS 1764-01’ (S. alandiae), ‘SS 1763- 23’ (S. albicans), ‘SS 1825-10’ (S. cardiophyllum), ‘SS 1735-01’ (S. demissum), ‘SS 1920-01’ (S. microdontum) and ‘SS 1724-06’ (S. sparsipilum).