Effects of Different Low Temperature Treatments at Heading-filling Stage on Quality of Main Rice Varieties in Sanjiang Plain

To explore effect of low temperature on quality of rice at heading-filling stage，taking Longjing 29，Longjing 31 and Longjing 46 as experimental materials，low temperature tests of daily average temperature of 17 ℃/3 d and 16 ℃/5 d on rice were conducted by using artificial climate chamber.Through study of rice quality after low temperature treatment，it was found that low temperature led to decrease of brown rice rate，milled rice rate and head rice rate，increase of protein content，and decrease of the highest viscosity and hot paste viscosity of RVA characteristic parameters.In 2016，low temperature promoted synthesis of amylose，while in 2017，low temperature inhibited synthesis of amylose at early stage of heading and filling，and promoted synthesis of amylose at middle and late stage of filling.Suitable low temperature could improve taste score of strong cold tolerance varieties and reduce taste score of general cold tolerance varieties.Different low temperatures had different effects on disintegration value，reduction value and recovery value of different varieties at different growth stages，which was related to complexity of RVA spectrum characteristic parameters of rice and need further study.