Physicochemical Properties And Its Relationship With Eating-quality Value Of Indica Rice Under Different Ecological Regions In Southwest China

With the improvement of people’s living standard,improving rice quality,speeding up the process of quality improvement,perfecting the rice quality evaluation system and meeting the needs of people’s living and consumption level are one of the most urgent tasks facing China’s rice quality production at present.In this study,36 indica rice varieties were used as materials to study their milling quality,appearance quality,content changes of main components,RVA characteristic value,eating quality and the relationship between physicochemical indexes of rice and eating quality in the three ecological regions of southwest Yunnan,Guizhou and Sichuan.The main results are as follows(1)This study confirmed the changes of the taste value and physicochemical indexes of rice quality of 36 national standard high-quality indica rice varieties in southwest China under the ecological zones of Yunnan,Guizhou and Sichuan.Chalkiness degree and chalky grain rate in rice appearance quality,brown rice rate in rice milling quality and RVA characteristic value are easily affected by environmental factors,while grain type is mainly controlled by genotype.(2)The influence of meteorological factors on rice quality from heading to maturity is mainly reflected in temperature and sunshine hours,increased temperature,decreased brown rice rate and milled rice rate in milled rice quality,increased whole milled rice,increased chalky grain rate and chalkiness degree in appearance quality,increased peak viscosity and disintegration value in RVA characteristic value,decreased reduction value,and increased rice eating quality.With the increase of sunshine hours,the peak viscosity and disintegration value in RVA characteristic value will increase,and the cold glue viscosity and reduction value will decrease.Increased rainfall is not conducive to protein accumulation.(3)According to the comprehensive score of eating quality and the comprehensive score of stability value of physical and chemical indexes,the tested varieties are divided into four types: high eating quality environmentally stable varieties(HTHS),high eating quality environmentally sensitive varieties(HTLS),low eating quality environmentally stable varieties(LTHS)and low eating quality environmentally sensitive varieties(LTLS).The high eating quality environmentally stable varieties have high eating quality and good adaptability in southwest China.The varieties of C Liangyouhuazhan,Deyou 4923,Chuanyou 6203,Fengyouxiangzhan,Rong18 you 2348,Yixiangyou 2168,screened in this experiment can be further popularized and planted in southwest China.The environmentally sensitive varieties with high eating quality have high eating quality,but their physical and chemical indexes are easily affected by ecological conditions.Yixiangyou2115,Yixiangyou3728,Chuanyou6203 and diantun 502 can further tap their potential.(4)This experiment analyzed the relationship between the eating quality of Indica rice and other quality indexes in southwest China.The results obtained by using the taste meter are consistent with the eating quality evaluation measured by RVA characteristic value.The eating quality of Indica rice in southwest China can be evaluated by using the taste meter.Rice milling factor has a very significant contribution to the eating quality,and chalkiness is not necessarily a negative effect on rice eating quality.The selection of rice varieties with high eating quality should first consider the low protein content and high percentage of whole rice,followed by low amylose content and high amylopectin content.In this study,the main ranges of physicochemical indexes and RVA characteristic values of treatments with eating quality exceeding 75 points are amylose content(14.35%~18.98%)and amylopectin content(58.27%~67.06%),Protein content(6.34%、8.33%),PKV(320.63~361.50),BDV(155.92~215.13),SBV(-151.50 ~-21.05),chalkiness(1.53 ~ 5.20).