Abstract:

The RVA profile is one of the key characters in evaluating the pasting property of the rice starch, and has been a primary index for improving the taste quality the rice. While the assessment of the local rice resource has always been the important part of the genetic improvement of crop, the research on the diversity of the RVA profile among the local rice resources can offer a basis for the further utilization of the local resources. In this paper, 368 late japonica rice cultivars in Taihu Lake area collected around 1950s were employed to performe the RVA profiles. The results showed that the rice starch RVA profile was different among tested cultivars. And the RVA parameters of different materials were also found significantly different from each other, exhibiting continuous variation from indica type to glutinous type, which consequently formed four groups. The setback viscosity value of a large portion of the local germplasm (about 51.9% in all samples) ranged from 300 to 1 000 cP. This portion of the materials thus fallen into typical japonica cultivar, and the corresponding RVA profile belonged to the category A. A few germplasm (such as Dahongdao, Zaorihuangdao, Shanghaiqing, Suzhouqing, Manghonggu) had characteristic RVA profile same as that of glutinous cultivars, the corresponding RVA profile was the category C. While some RVA profiles of other germplasm (such as Jinguhuang, Manbaidao, Cuyingyangwandao, Xidiegu, Ligengqing) were similar to that of typical indica cultivar, and corresponded to the category D. In the sampled cultivars, some of which (such as Tianxiadiyizhong, Daqingzhong, Huanggudadaotou, Yaoaizi, Yushanzhong) had RVA profile of cultivars with good quality, namely, the setback value was negative. The RVA profiles of Taihu lake area local cultivars indicated there were significant diversities in rice starch quality. Further, the generalized heritability diversity index of every characteristic value was calculated and all of indices were more than 1, among them that of breakdown reached to 2.06. Correlation analysis showed that characteristic values of RVA profile were correlated with each other, and the rice RVA profile characteristics could be described quantitatively by breakdown and setback.

Key words: Taihu lake area, Local cultivars, Late japonica rice, RVA profile, Diversity