Variation Characteristics Of Yield And Quality For Double-cropping High-quality Indica Rice In Different Ecological Regions

With the development of economy and the improvement of people's living standard,the problem of rice quality has attracted more and more attention.Therefore,a study on the temperature and light adaptation characteristics of high-quality rice varieties in southern China was carried out to provide reference and theoretical basis for exploring the relationship between the formation of rice yield and quality and temperature and light conditions as well as for the regionalization of high-quality rice cultivation.From 2017 to2018,four high-quality indica rice varieties and one high-yield control variety were used to carry out experimental research on the variation characteristics of yield and quality in different ecological regions of high-quality double-season indica rice in south China in Jiangxi province,Xingguo county and Guangzhou city of Guangdong province(respectively at higher,medium and lower latitudes).the main research results are as follows:1.With the decrease of latitude,the number of days in the whole growth period of rice generally shows a downward trend,in which the shortened main growth period is from sowing to full heading,while the range from full heading to mature period is relatively small.The shortening of the whole growth period of late rice is more obvious than that of early rice.With the decrease of latitude,the effective accumulated temperature during the whole growth period of early rice basically showed an increasing trend.However,late rice showed a decreasing trend.2.With the decrease of latitude,the shortening of growth period leads to the corresponding decrease of yield.The yield of early rice decreased as latitude decreased,but there was an inter-annual difference between the two years.As the latitude of late rice decreases,the yield also shows a decreasing trend.The yield of late rice in Guangzhou(lower latitude)was significantly reduced by 14.2% and 18.5% on average over the high point(higher latitude).Decreasing latitude is generally beneficial to improving the processing quality of early rice,but the changes of processing quality of high-quality late rice vary from variety to variety.The appearance quality of high-quality early and late rice is not obviously affected by ecological areas.The gel consistency of high-quality early and late rice is higher in low latitudes than in high latitudes.Amylose content is lower in low latitudes than in high latitudes,but there are interannual differences.The protein content is not obviously affected by the ecological regions.In two years,the peak viscosity and disintegration values of different ecological regions showed a downward trend with the decrease of latitude,but in 2017,the peak viscosity and disintegration values of late rice showed an upward trend with the decrease of latitude,indicating that the RVA spectrumcharacteristic values had interannual differences in late rice season.Correlation analysis showed that the RVA profile characteristic value of early rice showed a significant positive correlation with the lowest daily temperature and average daily temperature from heading to maturity.The lower lowest daily temperature and average daily temperature were helpful to increase the peak viscosity,thus improving the cooking and eating quality of rice.The percentage of whole milled rice of early indica rice was significantly positively correlated with the light hours during the whole filling and setting period and the daily average temperature at the early filling stage.The results showed that the higher average daily temperature and the more light hours of early rice were beneficial to the improvement of the whole rice rate.However,the greater the daily temperature difference during the whole grain filling and setting period of late rice,the higher the milled rice rate and the milled rice rate.