Grain sink removal increases stalk juice yield, sugar accumulation, and biomass in sweet sorghum [Sorghum bicolor (L.) Moench

Abstract

Sweet sorghum is cultivated primarily for its sugar-rich stalks. The extent to which stalk sugar accumulation occurs is determined by several factors including the grain sink. A Genetic system exists whereby the grain sink can be eliminated to maximize sugar accumulation in the stalks. Before engaging in the development of such system, establishing the extent to which stalk sugar can be improved by removing the grain sink becomes necessary. The aim of this study was to determine the effect of eliminating the grain sink on biomass and sugar accumulation. The experiment consisted of two factors, genotype and sink load. The genotype factor consisted of 22 sweet sorghum lines of variable sugar content, and the sink factor consisted of no-grain and full-grain set. Treatments were arranged in split plot in a randomized complete block design with genotypes assigned to the main plot and the sink effect to the subplot. The study was conducted in four replications in three environments. The no-grain sink treatment was applied by manually removing the panicles prior to anthesis. Analysis of the data collected from one-meter sections of each plot at physiological maturity showed that the genotype effect was significant (P ≤ 0.01) for all traits. Elimination of the grain sink prior to anthesis significantly increased °Brix, wet and dry biomass, and total sugar by 18, 28, and 43%, respectively. These results justify further development of sorghum varieties without a grain sink to maximize sugar yield for biofuel production.