| Field experiment was conducted in 2018 and 2019.The main research contents and research results were as follows:1.In this study,23 japonica rice varieties with high quality from Liaoning province(5),Jilin province(5)and Heilongjiang province(13 varieties including 3 Japanese varieties)were collected as materials,which planted in Panjin City of Liaoning Province,Gongzhuling of Jilin Province and Wuchang Rice Research Institute of Heilongjiang Province under the condition of unified cultivation and management to study the quality differences of these japonica rice varieties in different regions of Northeast China.The results showed that,compared with the Jilin and Heilongjiang,the processing quality of northern japonica rice varieties was generally higher when they were planted in Heilongjiang,and the difference was not significant.In terms of grain type,the ratio of length to width of northern japonica rice varieties is smaller and rice grains are shorter when planted in Heilongjiang.In appearance,when planted in Liaoning,the chalky grain rate was 11.79-41.35%,and the chalky degree was 2.42-16.19%.When planted in Jilin,the chalky grain rate was 9.89-34.29%,and the chalky degree was 2.35-14.33%.The chalky grain rate and chalky degree was 8.51-37.92%and 2.74-8.22%when planted in Heilongjiang.The chalky grain rate and chalkiness degree were Liaoning>Jilin>Heilongjiang,and the appearance quality was the best when planted in Heilongjiang.In cooking tasted quality,the amylose content and protein content of northern japonica rice varieties were Liaoning>Jilin>Heilongjiang,while the glue consistency was Liaoning<Jilin<Heilongjiang.In RVA spectrum characteristic value,the peak viscosity,hot paste viscosity,final viscosity and breakdown of northern japonica rice varieties were the highest when planted in Heilongjiang,while the setback and consistence were the lowest when planted in Heilongjiang.In the starch thermodynamic properties,the enthalpy and retrogradation enthalpy were the lowest when planting in Heilongjiang,and the content of small starch particleswas the highest when planted in Heilongjiang,while the content of large and medium starch particles was the lowest.The rice planted in Heilongjiang has the lowest hardness,the highest viscosity and relatively high elasticity,with a taste value of 63.7-80.9 and the best taste quality.2.The representative high-quality japonica rice varieties in Liaoning Province(5),Jilin Province(5)and Heilongjiang Province(5)and the representative high-quality japonica rice varieties in Jiangsu Province(5 soft rice varieties and 5 non-soft rice varieties)were planted in their best ecological regions,and the quality differences between southern and northern japonica rice were compared.The results show that compared with Jiangsu Province,the processing quality of the three northern provinces was better.In grain type,compared with Jiangsu non-soft rice,the rice grains of northern japonica rice varieties were shorter and smaller;Compared with soft rice,rice grains were slender.In appearance,compared with northern japonica rice,the chalky grain rate and chalky degree of Jiangsu soft rice and non-soft rice varieties were significantly higher,and the appearance quality was poor.There was no significant difference in amylose content between Jiangsu non-soft rice varieties and northern japonica rice,but compered with northern japonica rice,its protein content was significantly higher,with a taste value of 56.9-66.5,and its taste quality was poor.Compared with northern japonica rice,Jiangsu soft rice has low amylose content,high protein content,low hardness and high viscosity,and its peak viscosity and disintegration value were higher than those of northern japonica rice,while its reduction value and retro gradation value were small,and its taste value was 67.0-78.0.Northern japonica rice varieties have higher amylose content,lower protein content,higher hardness,higher elasticity and higher starch granule content,and compared with Jiangsu soft rice,the taste value was 71.0-80.9,which was higher,but there was no significant difference.3.On the basis of the above preliminary conclusions,39 japonica rice varieties participating in the second national high-quality rice variety taste quality evaluation activities were used as materials to study the differences in quality of some high-quality japonica rice in China,and 15 japonica rice varieties that won the Gold Award for Quality Taste were selected as materials,which were divided into two regions:South and North.The quality differences between South and North high-quality japonica rice were systematically compared to further verify the research results of the first two parts.The results showed that The 39 japonica rice varieties participating in the second national high-quality rice variety taste quality evaluation activities had great differences in grain type,chalkiness rate and chalkiness degree.In terms of cooking taste,the taste value measured by the rice taste meter and the sensory score of experts were 44.00-82.00 and 52.20-91.86,respectively.Amylose content of rice,setback,consistence in RVA spectrum,stickiness and balance in texture characteristics of rice were significantly negatively correlated with taste value of rice,with correlation coefficients of-0.39,-0.60,-0.57,-0.37 and-0.56,respectively.However,the peak viscosity and breakdown in RVA spectrum were significantly positively correlated with the taste value of cooked rice,with correlation coefficients of 0.32 and 0.36.Compared with northern high-quality japonica rice,chalkiness rate and chalkiness degree of southern high-quality japonica rice increased by 178.78%and 139.11%,respectively;amylose content decreased by 28.25%,protein content increased by 7.37%;setback and consistence in RVA spectra of rice flour decreased by 12.00%and 21.19%,respectively.The absolute values of stickiness and balance in texture characteristics of cooked rice increased by 16.15%and 15.00%,respectively;The appearance of northern japonica rice was crystal clear,chalkiness degree was 0.50%-3.50%,amylose content of rice was high,protein content was low,and taste was 56.00-74.00,the taste value measured by rice taste meter was 56.00-74.00,and the sensory score of experts was 86.14-90.67.However,the appearance of southern japonica rice was relatively turbid with chalkiness degree of 1.86%-11.21%.Although the protein content was high in rice,the amylose content was low,the rice cooked was soft and sticky,and the taste value was 54.00-82.00,the taste value measured by rice taste meter was 54.00-82.00,and the expert sensory score was 82.29-91.86.There was no significant difference between the taste value measured by rice taste meter and the expert sensory score between southern and northern high-quality japonica rice..In conclusion,when Northern Japonica rice was planted in Northeast China,rice quality was the best in Heilongjiang Province,but the difference was not significant.Northern japonica rice has higher amylose content,lower protein content and better elasticity,while southern japonica rice has lower amylose content and soft and sticky rice.However,due to the high temperature and high humidity environment,its protein content has higher than that of northern japonica rice under the same nitrogen fertilizer level,and its taste quality wasslightly insufficient compared with northern japonica rice,but the difference was not significant.The analysis of quality differences of some high-quality rice varieties in China also confirms this conclusion.Therefore,under the relatively high protein content,it was an important way to further improve the rice quality of southern japonica rice by appropriately reducing the amylose content to make the rice soft and waxy. |
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