Cassava root starch characteristics in Ugandan local varieties, elite introductions and their half SIB populations.

Abstract

Different important varieties of cassava are grown and used in Uganda for a range of applications based on their characteristics though they lack the right combination of culinary and industrial properties required for the different uses. In addition, no attempts have been taken to document and understand the starch they produce and how it can be suitably used. Previously released varieties that are reportedly substandard in root qualities were improved by hybridization with better-quality local farmer-preferred varieties. To understand the starch properties of the obtained progenies, a study was undertaken to examine: 1) starch physicochemical characteristics in both introduced and local varieties; and 2) the variation in starch properties of F1 progenies from intercrosses of local and introduced cassava varieties. Parental lines including local varieties (Bao, Nyaraboke, Kakwale, and Bamunanika) and introductions (SE/95/00036, NASE 10, NASE 12, TME 5, and TME 14) were used. At maturity, 1077 F1 were selected, cloned (6-8 plants per genotype) and established in a single-row trial for root quality assessment. Root analyses were performed per clone for starch quantity, functional, nutritional and quality properties. Considerable variations were observed in a number of starch properties. Starch granule sizes ranged on average from 2-20μm with dominantly truncated shapes. Starch viscosity and pasting properties were significantly (P < 0.05) different among F1 families and parental lines. Amylose content ranged from 19-25% among the progenies and the parental lines. Solubility and swelling power ranged from 1.3-7.7g/100 g and 50 -75g/100g starch at 60oC respectively. Fresh root starch yield ranged from 17-34% with dry matter ranging from 36.7-46.6%. Ash and lipid content varied among the F1 families with respective means of 0.25% and 0.20%. These findings revealed the considerable genetic variations in starch properties for both local and introduced cassava genotypes and demonstrated their potential for utilization in various applications.