Effect of crop maturity and on-farm storage on sugar content and chip colour of potato (Solanum Tuberosum L.) tubers

Dry matter content and sugar levels were determined in the tubers of three potato (Solanum tuberosum L.) cultivars at four harvest dates, i.e. 60, 75, 90 and 105 days after planting and also before and after the on-farm storage. The reducing sugar content was found to be unacceptable for chip colour in tubers of Kufri Bahar at all harvest dates. It was high in Kufri Jyoti but within the acceptable limits for Kufri Chandramukhi at full maturity. At the time of on-farm storage, reducing sugar level and chip colour score in tubers of Kufri Jyoti were 2.2 mg g⁻¹ fw and 4.9 respectively. These values for reducing sugars level and chip colour score decreased to 1.32 mg g-¹ fw and 2.6 in heap, 1.16 mg g-¹ fw and 1.7 in katcha pit and 1.37 mg g⁻¹ fw and 3.3 in pucca pit respectively after 90 days of storage. Thus indicating the benefit of on-farm storage, especially the katcha pit method, for improving the processing quality of potato tubers.