Determination of three soluble sugars in stem juice of sweet sorghum by anthrone colorimetry

Sugar content in stem is an important agronomic character of sweet sorghum (Sorghum dochna). The determination of the composition and content of soluble sugar in sweet sorghum is the premise of QTL mapping and character improvement of sweet sorghum. In this study, the content of sucrose, fructose and glucose was determined by improved anthrone colorimetry using 255 populations of ‘Xinliang 52’ and ‘W452’ recombinant inbred Lines of grain sorghum as materials. The results showed that the best color developing time of soluble sugar was 10 min and the color developing temperature was 100 ℃. The optimal treatment condition for sucrose determination was 1 mol·L⁻¹ KOH solution for 10 min.The optimum temperature and time for the determination of fructose were 50 ℃ and 3 min. The optimized anthrone colorimetric method can be used to determine the sugar content of sweet sorghum juice with good precision and stability. The results showed that there was a significant positive correlation between the weight of the progeny of this variety and the total amount of soluble sugar, and the value of the correlation was 0.885. The Linear regression equation was y = 37.082 × total soluble sugar + 3.990.