Screening Of Single Cropping Late Japonica Rice Varieties With Good-quality And High-yield And Several Studies Of Synergy Of Quality And Yield In Jiangsu Area Along The Yangtze River

The experiment was carried out in the experimental farms of Yangzhou University in 2017-2018.63 late-maturing varieties planted along the southern part of Jiangsu Province were used as test materials to study the differences of yield and quality.And the rice varieties with good-quality and high-yield which were suitable to be planted in Jiangsu area along the Yangtze river were screened.Three types of japonica rice varieties with significant differences in taste quality and yield(including good taste quality and high yield type:Nanjing 46,Suxiangjing 100,Changruan 07-7;good taste quality and medium yield type:Ning 9044,Su 2250,Changjing 16-2;medium taste quality and high yield;Changnongjing 8,Huaixiangjing 15 and Wujing 215.)were used to study the different characteristics of yield and quality.And the the synergy mechanism of high quality and high yield of single cropping late japonica rice in Jiangsu area along the Yangtze river to investigated.The main results were as follows:1.In 2017,12 varieties(lines)with good taste quality and high yield were screened which were suitable to be planted in southern Jiangsu area along the Yangtze river,such as Nanjing 46,Su 1707,Suxiangjing 100,et.al.The average taste value of this type is 70.6 within a range of 65.2 to 77.6.The average yield is 9.7 t·hm-2 within a range of 65.2 to 77.6.In 2018,9 varieties(lines)with good taste quality and high yield were screened,such as Sujing 9,Changruan 07-7,Wuyu 6622,et.al.The average taste value of this type is 78.4 within a range of 70.8 to 85.3.The average yield is 9.9 t·hm-2 within a range of 9.6 to 10.3 t·hm-2.According to the results from 2 years,5 varieties with good taste quality and high yield were screened,including Changruan 07-7,Ning 9051,Nanjing 46,Suxiangjing 100 and Changruan 07-10.Some quality indexes of two-year's experiments which were closely related to the taste value,and the correlation coefficient was more than 0.5,including head milled rice(0.509**),gel consistency(0.520**)and breakdown(0.601**).The quality indexes with closely negative correlation to taste value and correlation coefficient was more than-0.5,including amylose content(-0.604**),protein content(-0.635**),final viscosity(-0.541**)and setback(-0.623**).2.There were significant differences in yield formation among rice varieties with different types.The yield of the type with good taste and high yield was 15.35%higher than the type with good taste and medium yield.The panicle numbers,spikelets per panicle,percentage of filled grain and 1000-grain weight were 0.73%,5.17%,3.29%and 2.21%higher than the type with good taste and medium yield,respectively.The percentage of filled grain had significant difference.Comparing with the type of good taste and medium yield,the numbers of stem tillers of the type with good taste and high yield in jointing and heading period were relatively lower,while the stem tillers numbers and the ratio of productive tillers to total tillers were 1.92%and 12.47%higher respectively in maturity period.The leaf area index in heading and maturity period and high efficiency leaf area in heading period of the type with good taste and high yield were 5.08%,24.5%and 17.67%higher than the type with good taste and medium yield,respectively.While the decreasing rate of leaf area,secondary branches and grain density were 13.63%,38.47 and 10.64%lower respectively than the type with good taste and medium yield;the dry matter accumulation,the ratio of biomass to total in the period of heading to mature,and the crop growth rate,the net assimilation rate and photosynthetic potential in this period were 54.78%,27.27%,24.46%,18.18%and 17.67%higher than the type of good taste and medium yield,respectively.3.There were significant differences in quality indexes among rice varieties of different types.The type of good taste and high yield was 25.32%higher than the type of medium taste and high yield.Mainly in the appearance,viscosity and balance degree,they were 38.81%,36.30%and 37.40%higher,respectively,while the hardness was 2.86%lower.The mean daily temperature in grain filling period and accumulated temperature of the type of good taste and high yield were 6.6%and 1.84%lower than those of the type of medium taste and high yield,respectively.Among the indexes of physicochemical characteristics of rice,the amylose content and protein content;the setback and consistence in RVA parameters;the water absorption rate,expansion ratio,iodine blue value in cooking characteristics and the hardness in texture characteristics of the type of good taste and high yield were 37.67%?6.67%;159.9%?18.64%;12.71%?13.92%?51.94%and 22.4%lower respectively,than those of the type of medium taste and high yield.While the gel consistency,peak viscosity,through viscosity,breakdown,final viscosity,dry matter and springing,stickness and balance in texture characteristics were 19.92%,14.96%,13.96%,15.96%,1.83%,11.48%,8.1%,7.1%and 23.3%higher than those of the type of medium taste and high yield respectively.The onset temperature,peak of gelatinization temperature,conclusion temperature,retro gradation enthalpy and retro gradation in thermodynamic characteristics were 2.46%?3.89%?2.92%?32.73%and 39.28%lower than those of the type of medium taste and high yield,respectively,while the gelatinization enthalpy was 10.10%higher.