| Rice is the most important staple crop for people in Guangdong province, and improvement on rice grain quality is critical for meeting peoples' demands for seeking higher quality of life. As rice breeding advances, grain quality of rice varieties in Guangdong are increasing overall. However, it still has several problems related to the issue on these rice varieties. Rice grain quality is a complex trait made up of processing character,appearance character, cooking and eating quality. It can be further measured by covering the rate of brown rice(BR), the rate of head rice(HR), the ratio of chalky rice(CR),chalkiness(C), grain shape(GS), amylase content(AC), gel consistency(GC), and test quality(TQ). Concentrating on these indicators, the present study reviewed grain quality performance of rice varieties involved in regional yield trails in Guangdong province during 2005 to 2014. Furthermore, pedigrees of high quality varieties, as well as limiting factors of failed the test were analyzed. Out comes from the study may provide reference on improvement of grain quality in the future. The main results are as following:1. Totally 1904 tested varieties(without CK, glutinous rice and special rice) from 2005 to 2014, including 595 conventional rice and 1309 hybrid rice were reviewed and analyzed with the 8 indicators mentioned above. The proportions of quality grade were in different distribution, and the ones from late cropping were better than the ones from early cropping.The proportions of quality grade from conventional rice concentrated on Provincial Standard ? was 47.31%, and the one from hybrid rice concentrated was 23.07%.Therefore, conventional rice was better than hybrid rice.2. In conventional rice, the variation range of GS from early cropping and late cropping were 95.65%-100% and 97.06%-100%, the variation range of BR from early cropping and late cropping were 83.72%-100% and 91.18%-100%, the variation range of TQ from early cropping and late cropping were 79.41%-100% and 96.30%-100%, the variation range of GC from early cropping and late cropping were 80.00%-100% and 85.30%-100%, the variation range of C from early cropping and late cropping were 40.91%-100% and53.33%-100%, the variation range of CR from early cropping and late cropping were45.45%-100% and 73.33%-100%, the variation range of AC from early cropping and latecropping were 21.74%-91.30% and 54.84%-96.87%, the variation range of HR from early cropping and late cropping were 0-100% and 88.24%-100%. Thus, GS, BR, TQ and GC were in a high compliance rate in rice quality characters from early cropping and late cropping of conventional rice, which were small fluctuation. The quality rate of AC, CR and C were different in different croppings, and the rate was in the rise. The quality rate of HR was low, and the rate was in the big fluctuation in different cropping. Therefore, HR was the key point in conventional rice quality.3. In hybrid rice, the variation range of GS from early cropping and late cropping were69.23%-88.24% and 72.31%-95.40%, the variation range of BR from early cropping and late cropping were93.10%-100% and 90.63%-100%, the variation range of TQ from early cropping and late cropping were 69.35%-98.46% and 91.43%-100%, the variation range of GC from early cropping and late cropping were 75.81%-100% and 83.08%-100%, the variation range of C from early cropping and late cropping were 1.56%-92.75% and7.81%-97.01%, the variation range of CR from early cropping and late cropping were4.84%-79.71% and 17.19%-94.03%, the variation range of AC from early cropping and late cropping were 40.58%-85.29% and 56.72%-93.94%, the variation range of HR from early cropping and late cropping were 0-74.19% and 84.72%-100%. Thus, GS, BR, TQ and GC were in a high compliance rate in rice quality characters from early cropping and late cropping of conventional rice, which were small fluctuation. The quality rate of AC, CR and C were different in different croppings, and the rate was in the rise. The quality rate of HR was low, and the rate was in the big fluctuation in different cropping.4. Through analysis of parental origin of high-quality rice varieties, we can find out core materials which are from five categories. There are Fengbazhan, Yuexiangzhan,Texianzhan 25, External material and mutagenic material by Space Mutation. There were32 CMS Lines in hybrid rice from 2005 to 2014, and the highest utilization was Tianfeng A and the ratio was 10.38%. There were 8 two-line sterile lines, and the highest utilization was Y58 S and the ratio was 36.84%.5. There are four factors that limit T-test with grain quality of Provincial Standard of level three authorized. There are disease, lost, long growing period, and above factors.Among them, the ratio of disease is 74.23%, which is highest. |
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