Grain thickness of japonica rice varieties and its influence on eating quality.

The brown rice thickness and eating quality were investigated by using 71 varieties of northern japonica rice harvested in 2006 as materials.Brown rice thickness varied remarkably in the varieties with a coefficient of variation of 6.57%.The varieties with brown rice thickness from 1.81 mm to 2.10 mm accounted for 78.88% of the total varieties.The brown rice thickness was significantly positively correlated with taste value at 1% probability level.Taste value,protein content,amylose content and RVA viscosity properties of rice grains for five japonica rice varieties were determined following classification based on brown rice thickness with a grain separator.Brown rice thickness had a significant effect on rice quality parameters,such as rice protein content,RVA profile characteristics and taste value.The taste quality was improved with increasing thickness of brown rice for the same variety.Meanwhile the necessity on thickness as an index for breeding was discussed.