Abstract:

It is well known that environments had significant effects on the yield and quality of rice. Environment factors, such as cropping season (primarily temperature at filling stage) and management and cultural practices (plant density and time of nigtrogen fertilization, water management) may change the rice quality traits (chalkiness, Gel consistence, apparent amylose content and protein content etc.) and RVA viscosity. However, little information has been known about the effect of cropping location with different ecological conditions on the cooked rice texture and starch RVA property, and now the starch RVA viscosity and cooked rice texture are need to evaluate the eating quality of cooked rice. RVA breakdown viscosity was negatively correlated to the hardness of cooked rice. Stickiness was one of the main factors to determine the eating quality of cooked rice. In this paper, six indica rice cultivars with different levels of apparent amylose content (AAC) were selected to study their variation in the cooked rice texture and starch RVA properties among six cropping locations widely distributed in China (Gaozhou, Guangdong; Zunyi, Guizhou; Jiujiang, Jiangxi; Shi’en, Hubei; Yangzhou, Jiangsu; Hanzhong, Shaanxi). The results indicated that all six indica rice cultivars exhibited highly significant difference in stickiness and hardness as determined by Instron 4301 analyzer among 6 experimental locations. In Gaozhou, the 3 cultivars (Zheyou 1500, Qingliu’ai 1, and Liangyoupeijiu) exhibited the highest adhesiveness and stickiness values, while Zhongjian 2 had the lowest hardness, adhesiveness and stickiness values across all the locations. The significant difference was also detected for the parameters of RVA properties (hot, final, peak, breakdown, consistence and setback viscosity values), although the extent of difference was cultivar-dependent. The cultivars with middle, high AAC had similar RVA viscosity curves in Yangzhou, Zunyi and Hanzhong, and exhibited higher peak and breakdown viscosities in Gaozhou than in other locations, but low AAC cultivar Zhongjian 2 showed the lowest peak and breakdown viscosity in Gaozhou. The variances of 9 parameters (adhesiveness, stickiness, hardness, hot viscosity, final viscosity, peak viscosity, breakdown viscosity, consistence viscosity, setback viscosity) in genotype × environment interactions were significant at the 1% probability level. Based on the above coefficients of variation the parameters can be divided into three groups: adhesiveness was low; hot viscosity, final viscosity, peak viscosity, breakdown viscosity, consistence viscosity, stickiness and hardness were high; and setback viscosity was the highest. The high coefficients of variation of breakdown viscosity and stickiness, which proved to be closely related with the eating quality of cooked rice, indicated that there was a potential to improve the quality of rice cultivars. Taken together, the above results suggested that cropping location affected the eating quality of cooked indica rice. In order to bring all potentialities into full play to improve rice-eating quality, in addition to choosing high quality rice cultivars, suitable growing location must be considered.

Key words: Ecological condition, RVA property, Cooked rice texture, Starch, indica rice