Relationship between harvest date and sugar content of sweet sorghum stalks

High energy sorghum (Sorghum bicolor (L.) Moench) cultivars have been recently developed for grain and biomass production. Whole plant utilization is the target of this concept. The objective of this study was to identify the relationship between the harvest date and biomass yield. Experimental trials were conducted with the cultivar BR 505 in the years 1984/85, 1985/86 and 1986/87 to determine its performance as a high energy crop. High biomass and sugar yields were obtained at the physiological maturity stage of the plants. Sucrose and total sugars of the plant increased continually from the visible spikelet stage to the physiological maturity. However, reducing sugar level showed a fall over the same period. In the years 1984/85 and 1985/86 the total biomass yield was 38.9 and 52.0 t/ha respectively. Late sowing date which occurred in the year 1986/87 and the elimination of the supplementary N fertilization reduced significantly the biomass yield as well as the sugar level in the stalks. Grain production of the complementary N fertilization was not affected significantly.