31 - 36 Almodares.pmd

Sweet sorghum (Sorghum bicolor (L.) Moench) is a multiple-purpose crop which has been consumed as either food or feed and recently, industrially cultivated for liquid sugar and ethanol production. Biomass and carbohydrate composition of sweet sorghum are considered as important factors for industrial productions. Thus, in this study fresh stalk yield, total sugars, sucrose content and invert sugars of five sweet sorghum cultivars and four sweet sorghum lines were evaluated. The plants were harvested at soft dough, hard dough and post grain maturity stages. The highest amount of total sugar, sucrose content, invert sugars and fresh stalk yield were obtained in cv Rio (hard dough stage), cv Rio (hard dough stage), cv Vespa (maturity) and cv Sova (hard dough) respectively. The lowest of aforementioned parameters were found in cv Turno (soft dough), cv Turno (soft dough), line IS 4546 (maturity) and line IS 4546 (soft dough) respectively. The mentioned parameters were reduced by delaying harvest time of sweet sorghum cultivars and lines. At hard dough stage, sucrose and total sugar exhibited a positive correlation, while the correlation between sucrose and glucose, fructose and maltose was negative. Mannose, galactose and arabinose were not detected in sweet sorghum juice. The obtained results showed that the optimum harvest time for all sweet sorghum cultivars and lines should be conducted before post seed maturity.