Genetic diversity in the physicochemical properties of waxy rice (Oryza sativa L) starch

The genetic diversity in the physicochemical properties of starches from 56 waxy rice (Oryza sativa L) genotypes (34 of indica and 22 of japonica) was studied. The parameters included thermal and retrogradation properties tested by differential scanning calorimetry (DSC), pasting viscosity tested by rapid viscoanalyser (RVA), and flour swelling volume (FSV). Wide diversity was found in all the parameters. According to their gelatinisation temperature (GT), the waxy rice genotypes could be divided into two groups, a high-GT group and a low-GT group. A total of 15 genotypes were identified as high-GT, all belonging to the indica subspecies. There was about a 5 °C difference within each group and a 10 °C difference between groups. Many parameters were correlated with each other in all 56 waxy rices, but some correlations were also consistent and significant when comparing the high-GT group and the low-GT group separately. For example, hot paste viscosity (HPV) was positively correlated with onset temperature (To) and enthalpy of gelatinisation ((delta)Hg). The results suggested that initial screening in waxy rice breeding programmes for varieties with desirable starch properties for specific food uses could be efficiently accomplished using pasting profiles from the RVA.