Studies Of Comparison In Rice Quality Characteristics Of China And Japan

In our country, there is a wide gap between rice grain quality among varieties and the needs of the consumer market. The high-quality rice production and supply of rice has become the important constraints of rice production and circulation. Rice quality is a comprehensive performance which involves many influential factors. The formation process and the final performance evaluation are unknown clearly. Japan has insisted on the principle of high-quality rice production in rice breeding and production for a long time.With comparing the performance between Japanese high-quality rice varieties and Chinese varieties, we would know the limiting factors of rice quality in China and the means of analyzing and judging the forming reason. From 2006 to 2008, Chinese rice varieties and Japanese varieties were compared in three fields including different enviroment of cultivation, different grain fertilizer and comercial rice from Japan and China. In the experiment, Jiangsu japonica rice of China and Japanese japonica rice were used as materials divided into Chinese erect panicle, Chinese semi-erect panicle varieties, new Japanese varieties and old Japanese varities. The main results were as follows.1) Under the cultivation condition in Yangzhou, the appearance of new Japanese varieties was better, but its processing quality was poorer. Otherwise, grain shape and gel consistency of Chinese rice varieties were similar to those of Japanese varieties. The amylose content of Japanese rice varieties was lower than of Chinese varieties, but the protein contant was higher. The starch viscosity characteristics of Japanese rice varieties were in line with the characteristics of high-quality rice, especially the varietiy of Koshihikari, it showed the typical characteristis of high-quality involving higher vlaues of peak viscosity, higher breakdown and lower setback.2) Under the cultivation condition in Japan, the appearance of new Japanese varieties was better than that of the other three varieties. The protein content of all varieties was between 5% -7% and there was not obvious difference between Chinese varieties and Japanese ones. Japanese varieties performed better in eating quality, especially Koshihikar, its starch viscosity characteristies was more in line with high-quality varieties. The mensuration results of supplied rice varieties planted in the Japan and Yangzhou, China were compared in this study and the results showed the appearance quality and starch viscosity characteristics of all varieties under the cultivation condition in Japan was better than those of in Yangzhou. However, the protein content was significantly lower than that of Yangzhou.3) Under the cultivation condition in Yangzhou, the physiological characteristics of rice quality formation were compared and the results showed that the rice grain filling of Japanese varieties was more gentle than that of China.The filling rate of superior grains was slower than that of Chinese varieties, but the inferior grains was faster. The solube sugar content of Japanese varieties in stem and sheath was higher and the grain amylose accumulation went on a longer time. The starch synthase, ADPG pyrophosphorylase, starch branching enzyme activity in grains were lower in early grain filling stage.With the rice grain filling, the enzymes activities were increased and then decreased, and the time they reached the peak value was different. The enzymes activities of Japanese varieties were earlier and higher in the prophase of rice filling time than Chinese varieties, otherwise, the enzymes activities of inferior grains were higher during the whole rice grain filling period.4) Under the cultivation conditions in Yangzhou, the impact of different levels of grain fertilizer to the quality characteristics of rice varieties from China and Japan was sdudied. The results showed that the quality of the appearance was obviously improved , but at the same time the rice protein content significantly increased, Chinese varieties was more sensitive to the fertilizer application. Amylose content declined with the grain fertilizer increasing and Japonica variety Wu Xiang 14 was more susceptible to the effects of nitrogen fertilizer. Japanese varieties still showed high-quality characteristics under conditions of high level of grain fertilizer. There were differences of the changes of starch viscosity characteristics among varieties, but the overall performance became poorer with the change of nitrogen fertilizer. The Japanese high-quality varieties performed more stable and changed less with the impact of the grain fertilizer application.5) Comparing the commercial and large-scale production of rice from Jiangsu, China and Tokyo, Japan, the results showed that average protein content of Japanese rice was three percentage points lower than that of Chinese varieties. There was not obvious differences among amylose content, and gel consistency of Japanese rice was longer. The starch viscosity characteristics of Japanese rice were more in line with the general performance of high-quality rice and performed balanced with high peak viscosity, final viscosity, breakdown and small setback.