Methodical features of sugar content determination in sweet maize selection

A currently important task for the evaluation of breeding samples at all stages of the sweet maize selection is to control the sugar content in the sweet maize grain of technical maturity. The methodical features of the sugar content determination in the sweet maize grain using the example of the inbred line CE401 and hybrid F2(CE401 × Chornosteblova) were investigated. We compared the content of total sugar, monosaccharides and disaccharides in the grain on the twenty-first day after self-pollination (21 DAP), on the day of sampling and after storage of the same ears at subzero temperature. It was found that after storage of ears for 4.5 months at a temperature of –12 0C, total sugar content in grain of CE401 increased by 97.7 % and reached 46.84 % by mass of absolutely dry matter (ADM), and for F2(CE401 × Chornosteblova) – by 61.7 % and reached 15.93 %. Accordingly, the contents of mono- and disaccharides as components of total sugar content increased, although this increase in F2 (CE401× Chornosteblova) was very uneven for individual ears. Intact grains of the CE401 line contained 2.55 times more monosaccharides and 2.27 times more disaccharides compared to the F2 hybrid (CE401 × Chornosteblova). After keeping the ears at –12 ºC for 4.5 months, the share of total sugar content in ADM of the CE401B line grain exceeded the similar value of the F2 hybrid (CE401 × Chornosteblova) by 2.94 times, monosaccharides by 3.54 times, and disaccharides by 2.54 times. The degree of such increase depends on the genotype of the initial breeding material. For the sweet maize selection, it is recommended to determine the total sugar content and its fractions on the day of sampling, and to refuse the common practice to store of grain samples at subzero temperature before analysis. Key words: Zea mays L., grain in technical maturity, total sugar content, mono- and disaccharide contents, determination procedure, grain storage under subzero temperature